Myeloproliferative neoplasms: Morphology and clinical practice

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.

Diagnostic and management strategies for Myeloproliferative Neoplasm-Unclassifiable (MPN-U): An international survey of contemporary practice

Myeloproliferative Neoplasm-Unclassifiable (MPN-U) is defined as an MPN that fails to meet the diagnostic criteria for any of the other defined classical or 'non-classical' MPNs. The reported incidence is variable, dependent on appropriate recognition, and the clinical course can be highly variable ranging from an indolent disorder through to an aggressive disease course with a significant risk of thrombosis, bulky splenomegaly, and debilitating symptom burden. Clinicians frequently manage these conditions according to the clinical concerns e.g. splenomegaly akin to the phenotype, but no evidence base exists. Currently, there are no widely accepted guidelines to deal with both the diagnostic work up and subsequent clinical management of this entity. We hence surveyed major International MPN centres to gain an understanding of common challenges in MPN-U management in 2021 and aid identification of considerable practice variations where harmonisation would be desirable. Such information is vital to support future consensus guidelines in addition to informing further collaborative studies.

Therapeutic Plateletpheresis in Patients With Thrombocytosis: Gender, Hemoglobin Before Apheresis Significantly Affect Collection Efficiency

Background: Thrombocytosis is a common symptom in myeloproliferative neoplasms (MPN), and excessive proliferation may deteriorate into thrombosis, bleeding, myelofibrosis, and may ultimately convert to acute leukemia. This study aimed to investigate the collection efficiency of plateletpheresis (CEPP) and factors influencing its efficacy in patients with thrombocytosis.

Materials and Methods: From September 2010 to December 2016, 81 patients from two institutions in China with myeloproliferative neoplasms and thrombocytosis accompanied by severe symptoms were treated with plateletpheresis by Fresenius COM. TEC machine.

Results: After apheresis, the median CEPP was 20.71% (IQR: 9.99–36.69%) and median PLT reduction rate was 25.87% (IQR: 21.78–36.23%). Further analysis showed that no significant difference was observed between PLT count with 800–1,000 × 10⁹/L and > 1,000 × 10⁹/L. The PLT counts significantly decreased (P < 0.001) after plateletpheresis, the red blood cell (RBC), white blood cell (WBC), hemoglobin (HGB), and hematocrit (HCT) levels showed no significant differences before- or after- plateletpheresis. Multivariate analysis showed that female sex (P = 0.009) and HGB (P = 0.010) before apheresis were associated with CEPP. Female (P = 0.022), HCT (P = 0.001) and blood volume (P = 0.015) were associated with the PLT reduction rate. Furthermore, symptoms were relieved after apheresis in patients whose PLT count was 800–1,000 × 10⁹/L accompanied with symptoms.

Conclusions: It is reasonable to perform plateletpheresis when the PLT count is over 800 × 10⁹/L and patients are complicated by clinical symptoms such as dizziness, headache, somnolence, and stupor. Plateletpheresis is effective in removing PLTs especially in females with high HGB.

The Contemporary Approach to CALR-Positive Myeloproliferative Neoplasms

CALR mutations are a revolutionary discovery and represent an important hallmark of myeloproliferative neoplasms (MPN), especially essential thrombocythemia and primary myelofibrosis. To date, several CALR mutations were identified, with only frameshift mutations linked to the diseased phenotype. It is of diagnostic and prognostic importance to properly define the type of CALR mutation and subclassify it according to its structural similarities to the classical mutations, a 52-bp deletion (type 1 mutation) and a 5-bp insertion (type 2 mutation), using a statistical approximation algorithm (AGADIR). Today, the knowledge on the pathogenesis of CALR-positive MPN is expanding and several cellular mechanisms have been recognized that finally cause a clonal hematopoietic expansion. In this review, we discuss the current basis of the cellular effects of CALR mutants and the understanding of its implementation in the current diagnostic laboratorial and medical practice. Different methods of CALR detection are explained and a diagnostic algorithm is shown that aids in the approach to CALR-positive MPN. Finally, contemporary methods joining artificial intelligence in accordance with molecular-genetic biomarkers in the approach to MPN are presented.

Clinicopathological characterisation of myeloproliferative neoplasm-unclassifiable (MPN-U): a retrospective analysis from a large UK tertiary referral centre

Myeloproliferative neoplasm-unclassifiable (MPN-U) presents an MPN-type phenotype that fails to meet diagnostic criteria for other MPN variants. Variability in the clinicopathological phenotypes presents many challenges. Amongst a registry cohort of 1512 patients with MPN, 82 with MPN-U were included, with a median (range) age of 49·7 (13-79) years. Albeit heterogeneous, common presentation features included raised lactate dehydrogenase, thrombocytosis and clustered/pleomorphic megakaryocytes on trephine biopsy. Thrombosis was common (21%), necessitating vigilance. The median event-free survival was 11·25 years (95% confidence interval 9·3-not reached), significantly shortened in cases with lower platelet counts (<500 × 10⁹ /l) and a leucocytosis (≥12 × 10⁹ /l) at presentation. Generation of potential MPN-U prognostic scores is required.

Clinical and Molecular Attributes of Patients With BCR/ABL1-negative Myeloproliferative Neoplasms in India: Real-world Data and Challenges

INTRODUCTION

Classic BCR/ABL1-negative myeloproliferative neoplasms (MPNs) are characterized by clinical and genetic heterogeneity and include 4 distinct constituents. Very little data on clinical presentation and epidemiology of the same is available from the Indian setting.

PATIENTS AND METHODS

Patients referred to Hematology-Oncology from January 2018 to August 2020 with suspected MPNs were included in the analysis and prospectively followed-up. All patients were initially screened, and only those meeting the updated World Health Organization 2016 criteria were included in the analysis. Epidemiologic, clinical, and molecular characteristics were documented, and patients were followed-up prospectively.

RESULTS

A total of 233 patients were referred for evaluation of MPN, of which 63 were included in the analysis, including 39 males and 24 females. The median age at diagnosis was 57 years (range, 28-82 years), and 38% patients were younger than 50 years of age. The most common presentations were incidental detection in 35 (55.5%), abdominal symptoms in 13 (20%), fatiguability in 7 (11%), and recent vascular events in 6 (9.5%) patients. Final diagnosis was polycythemia vera in 27, essential thrombocytosis (ET) in 21, prefibrotic myelofibrosis in 9, and myelofibrosis in 6 patients. The frequency of driver mutations in polycythemia vera included JAK2 in 75%; in ET, JAK2 in 33%, CALR in 33%, and MPL in 4%; and in prefibrotic myelofibrosis, JAK2 in 66% and CALR in 33%. Aspirin was used for all patients along with risk-adapted cytoreduction with hydroxyurea. Ruxolitinib was reserved for symptoms refractory to hydroxyurea. After a median follow-up of 15 months (interquartile range, 10-28 months) from diagnosis, disease progression was noted in 4 patients. Two patients died at the end of the follow-up period, including 1 with secondary acute myeloid leukemia post myelofibrosis and one with ET and coexistent oral malignancy. The remaining 61 patients are alive and on regular treatment.

RESULTS

This is one of the first systematic descriptions and prospective follow-up of patients with BCR/ABL-negative MPNs from India. Our study indicates a younger median age of presentation and higher proportion of JAK2-unmutated disease across all subtypes. The primary role of bone marrow morphology and supportive role of somatic mutations in differentiating MPN subtypes is indicated.

CONCLUSIONS

This study sets the stage for a collaborative registry for defining epidemiologic data and long-term outcomes with MPN in India.

Cytokine Profiling in Myeloproliferative Neoplasms: Overview on Phenotype Correlation, Outcome Prediction, and Role of Genetic Variants

Among hematologic malignancies, the classic Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are considered a model of inflammation-related cancer development. In this context, the use of immune-modulating agents has recently expanded the MPN therapeutic scenario. Cytokines are key mediators of an auto-amplifying, detrimental cross-talk between the MPN clone and the tumor microenvironment represented by immune, stromal, and endothelial cells. This review focuses on recent advances in cytokine-profiling of MPN patients, analyzing different expression patterns among the three main Philadelphia-negative (Ph-negative) MPNs, as well as correlations with disease molecular profile, phenotype, progression, and outcome. The role of the megakaryocytic clone as the main source of cytokines, particularly in myelofibrosis, is also reviewed. Finally, we report emerging intriguing evidence on the contribution of host genetic variants to the chronic pro-inflammatory state that typifies MPNs.

Cytokine Profiling in Myeloproliferative Neoplasms: Overview on Phenotype Correlation, Outcome Prediction, and Role of Genetic Variants

Among hematologic malignancies, the classic Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are considered a model of inflammation-related cancer development. In this context, the use of immune-modulating agents has recently expanded the MPN therapeutic scenario. Cytokines are key mediators of an auto-amplifying, detrimental cross-talk between the MPN clone and the tumor microenvironment represented by immune, stromal, and endothelial cells. This review focuses on recent advances in cytokine-profiling of MPN patients, analyzing different expression patterns among the three main Philadelphia-negative (Ph-negative) MPNs, as well as correlations with disease molecular profile, phenotype, progression, and outcome. The role of the megakaryocytic clone as the main source of cytokines, particularly in myelofibrosis, is also reviewed. Finally, we report emerging intriguing evidence on the contribution of host genetic variants to the chronic pro-inflammatory state that typifies MPNs.

A provider's guide to primary myelofibrosis: pathophysiology, diagnosis, and management

Although understanding of the pathogenesis and molecular biology of primary myelofibrosis continues to improve, treatment options are limited, and several biological features remain unexplained. With an appropriate clinical history, exam, laboratory evaluation, and bone marrow biopsy, the diagnosis can often be established. Recent studies have better characterized prognostic factors and driver mutations in myelofibrosis, facilitated by use of next-generation sequencing. These advances have facilitated development of a management strategy that is based on both risk factors and clinical phenotype. For low-risk patients, treatment will depend on symptom severity. For patients with higher-risk disease, several treatments are available including JAK inhibitors, allogeneic hematopoietic stem cell transplant, and clinical trials using novel molecularly targeted therapies and rational drug combinations. In this review, we outline what is known about the disease pathogenesis, discuss an approach to reaching the diagnosis, review the prognosis of myelofibrosis, and detail current therapeutic strategies.

Myeloproliferative neoplasms: Diagnostic workup of the cythemic patient

Elevated peripheral blood (PB) cell counts, such as leukocytosis, thrombocytosis, and polycythemia, are often the presenting symptom in patients with myeloproliferative neoplasms (MPN). Because cythemias are nonspecific and may reflect either a reactive or neoplastic process, diagnostic workup of these patients is complicated and requires integration of numerous diagnostic modalities. Careful morphologic evaluation of the PB smear may provide insights into the underlying cause of the abnormal counts (such as the presence of teardrop erythrocytes in myelofibrosis or granulocytic dysplasia with left shift in atypical chronic myeloid leukemia). However, these morphologic findings need to be interpreted in concert with clinical findings and other laboratory results. In recent years, there has been a wealth of new genetic data in the field of MPN and many recurrent mutations have been identified, especially in cases lacking Philadelphia chromosome. Many of these genes impact the diagnosis and/or prognosis. Although certain mutations are preferentially enriched in specific MPN types, none of these mutations are disease defining; therefore, a thorough workup should always include a bone marrow biopsy for morphologic evaluation and diagnosis. This review will describe a comprehensive approach to the diagnosis of various MPN, with an emphasis on the diagnostic and prognostic implications of recurrent mutations in MPN.

Decreased survival and increased rate of fibrotic progression in essential thrombocythemia chronicled after the FDA approval date of anagrelide

First-line cytoreductive drug of choice in high risk essential thrombocythemia (ET) is currently hydroxyurea, a practice based on the results of a randomized study; second-line drugs of choice include pegylated interferon-α, busulfan and anagrelide. Anagrelide clinical trials were pioneered by the late Murray N. Silverstein (1928-1998) of the Mayo Clinic whose studies led to FDA approval in March 1997. The current study represents a retrospective examination of the potential impact of anagrelide therapy on survival and disease complications in ET. 1076 patients with ET were considered (median age 58 years; females 63%); risk distribution, according to the international prognostic score for ET (IPSET), was 28% high, 42% intermediate, and 30% low. Overall (OS), myelofibrosis-free (MFFS) and thrombosis-free survival data were compared for ET patients diagnosed before and after the 1997 FDA approval date for anagrelide; a significant difference was apparent in OS (P = .006; HR 1.4, 95% CI 1.1-1.7) and MFFS (P < .001; HR 4.2, 95% CI 2.7-6.5), in favor of patients diagnosed prior to 1997; the difference was sustained during multivariable analysis that included IPSET. Similarly stratified survival data in polycythemia vera (n = 665) and primary myelofibrosis (n = 1282) showed no similar impact on survival (P = .3 and .17, respectively). The current study represents a retrospective analysis and suggests significantly decreased OS and MFFS in ET patients diagnosed after the FDA approval date of anagrelide. Whether or not anagrelide therapy was to blame for the worsening of OS and MFFS over time cannot be assumed and requires validation in a prospective study.

The epidemiology and clinical characteristics of myeloproliferative neoplasms in Malaysia

Background

The evolution of molecular studies in myeloproliferative neoplasms (MPN) has enlightened us the understanding of this complex disease consisting of polycythaemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The epidemiology is well described in the western world but not in Asian countries like Malaysia.

Materials and methods

This retrospective national registry of MPN was conducted from year 2009 to 2015 in Malaysia.

Results

A total of 1010 patients were registered over a period of 5 years. The mean age was 54 years with male predominance. The ethnic distribution revealed that Chinese had a relatively high weighted incidence proportion (43.2%), followed by Indian (23.8%), Malay (15.8%) and other ethnic groups (17.2%). The types of MPN reported were 40.4% of ET (n = 408), 38.1% of PV (n = 385), 9.2% of PMF (n = 93), 3.1% of hypereosinophilic syndrome (HES) (n = 31) and 7.9% of unclassifiable MPN (MPN-U) (n = 80). Splenomegaly was only palpable clinically in 32.2% of patients. The positive JAK2 V617F mutation was present in 644 patients with 46.6% in PV, 36.0% in ET, 9.0% in PMF, and 7.4% in MPN-U, and had significantly lower haemoglobin (p < 0.001), haematocrit (p < 0.001) and white blood cells (WBC) (p < 0.001) than those with negative mutation. Significant differences in platelet and WBC count were detected in ethnic groups and MPN sub-types. There were more arterial thrombosis events seen in those with JAK2 V617F mutation as compared to venous thrombosis events (23.1% vs 4.4%). The bleeding rate was only 6.6%. Among the risk factors, previous thrombosis, old age (≥ 60 years) and hypertension were significantly correlated to positive JAK2 V617F mutation. The arterial thrombosis event is associated with higher presenting HB, HCT and PLT while the bleeding event is associated with lower presenting HB, HCT but higher PLT. The presence of JAK2 V617F mutation is associated with higher risk of arterial thrombosis.

Conclusion

Chinese ethnicity is associated with higher rates of MPN. The history of thrombosis, age ≥ 60 years and hypertension are risk factors that can be correlated to JAK2 V617F mutation. This study is instrumental for policy makers to ensure preventive strategies can be implemented in future.

Primary myelofibrosis: 2019 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm (MPN) characterized by stem cell-derived clonal myeloproliferation that is often but not always accompanied by JAK2, CALR, or MPL mutations; additional disease features include bone marrow stromal reaction including reticulin fibrosis, abnormal cytokine expression, anemia, hepatosplenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

Diagnosis of PMF is based on bone marrow morphology. Presence of JAK2, CALR, or MPL mutation, expected in ∼ 90% of the patients, is supportive but not essential for diagnosis. The revised 2016 World Health Organization (WHO) classification system distinguishes "prefibrotic" from "overtly fibrotic" PMF; the former might mimic ET in its presentation and it is prognostically relevant to distinguish the two.

RISK STRATIFICATION

Two new prognostic systems for PMF have recently been introduced: GIPSS (genetically inspired prognostic scoring system) and MIPSS70+ version 2.0 (mutation- and karyotype-enhanced international prognostic scoring system). GIPSS is based exclusively on mutations and karyotype. MIPSS70+ version 2.0 utilizes both genetic and clinical risk factors. GIPSS features four and MIPSS70+ version 2.0 five risk categories. MIPSS70+ version 2.0 requires an online score calculator (http://www.mipss70score.it) while GIPPS offers a lower complexity prognostic tool.

RISK-ADAPTED THERAPY

Observation alone is advised for MIPSS70+ version 2.0 "low" and "very low" risk disease (estimated 10-year survival 56%-92%); allogeneic stem cell transplant is the preferred treatment of choice for "very high" and "high" risk disease (estimated 10-year survival 0-13%); treatment-requiring patients with intermediate-risk disease (estimated 10-year survival 30%) are best served by participating in clinical trials. All other treatment approaches, including the use of JAK2 inhibitors, are mostly palliative and should not be used in the absence of clear treatment indications. Conventional treatment for anemia includes androgens, prednisone, thalidomide and danazol, for symptomatic splenomegaly hydroxyurea and ruxolitinib and for constitutional symptoms ruxolitinib. Splenectomy is considered for drug-refractory splenomegaly and involved field radiotherapy for nonhepatosplenic EMH and extremity bone pain.

ASXL1 mutations in Chinese patients with essential thrombocythemia

Essential thrombocythemia (ET) is characterized by thrombotic and hemorrhagic events. The association of clinical characteristics of Chinese ET patients and additional sex combs like 1 (ASXL1) mutations in these patients has remained to be elucidated. In the present study, 72 newly diagnosed Chinese ET patients were enrolled to determine ASXL1 mutations. Mutations in ASXL1, Janus kinase (JAK)2, calreticulin (CALR) and myeloproliferative leukemia (MPL) genes were detected using Sanger sequencing, and data were statistically analyzed. The frequencies of ASXL1, JAK2 V617F, CALR and MPL W515 mutations in ET patients were 19.4% (14/72), 29.2% (21/72), 31.9% (23/72) and 0% (0/72), respectively. Of note, 28 ET patients (38.9%) were negative for JAK2, CALR and MPL mutations; these patients were classified as triple-negative (TN). The frequency of ASXL1 mutations in patients with JAK2 V617F, CALR and TN mutations was 23.8% (5/21), 21.7% (5/23) and 14.3% (4/28), respectively. ASXL1-mutant patients exhibited significant propensities for thrombotic events compared with the ASXL1 wild-type (wt) cohort (42.9 vs. 12.1%; P=0.021). In addition, JAK2 V617F-mutant patients had a higher mean age compared with CALR-mutant (64.76 vs. 52.96 years; P=0.008) or TN patients (64.76 vs. 51.14 years; P=0.002). Furthermore, more white blood cells in the peripheral blood (PB) were observed in JAK2 V617F-mutant patients compared with those in TN patients (12.40 vs. 8.20×10⁹/l; P=0.02). In addition, CALR-mutant patients exhibited more platelets (PLT) in PB than JAK2 V617F-mutant patients (787.91 vs. 562.17×10⁹/l; P=0.047). TN patients had a significantly lower incidence of clinical symptoms, including dizziness, palpitation and chest congestion compared with CALR- or JAK2 V617F-mutant patients (14.1 vs. 39.1%; P=0.043 and 14.1 vs. 38.1%; P=0.050). No significant difference in progression-free survival was observed between ASXL1-mutant and ASXL1-wt patients (P=0.590). In conclusion, ASXL1-mutant ET patients are prone to experiencing thrombotic events. There was no significant difference in the occurrence of thrombotic events among CARL-mutant, JAK2 V617F-mutant and TN patients. Furthermore, ASXL1-mutant/TN patients exhibited a higher number of PLT than ASXL1/JAK2 V617F-double mutant patients. Therefore, ASXL1 mutations may be a risk factor for the occurrence of thrombotic events in ET patients.

Allogeneic hematopoietic stem cell transplant overcomes the adverse survival effect of very high risk and unfavorable karyotype in myelofibrosis

The prognostic importance of genetic information in primary myelofibrosis (PMF) was recently highlighted in a study of over 1000 cytogenetically-annotated patients; 5-year survival rates were 8% for very high risk (VHR), 27% "unfavorable" and 45% "favorable" karyotype. The current study addresses the practice-relevant question of whether or not allogeneic hematopoietic stem cell transplant (HCT) can overcome the detrimental survival effect of VHR or unfavorable karyotype. The study included 67 patients with PMF or secondary MF who received HCT at the Mayo Clinic and in whom pretransplant cytogenetic information was available. Dynamic international prognostic scoring system (DIPSS) risk distribution was 13% high, 66% intermediate-2 and 21% intermediate-1. Cytogenetic risk distribution was 11% VHR, 34% unfavorable and 55% favorable. At median post-HCT follow-up of 60 months for living patients (range 34-170), 28 (42%) deaths were recorded. Five-year survival was 62% and was not affected by VHR or unfavorable karyotype (P = .68). The salutary effect of HCT in patients with VHR or unfavorable karyotype was also apparent during analysis of a combined dataset that included a nontransplant cohort of 383 patients with PMF; multivariable analysis of the combined dataset (n = 450) resulted in HRs (95% CI) of 2.4 (1.6-3.6) for absence of transplant, 3.3 (2.2-4.8) for VHR karyotype, 1.6 (1.2-2.1) for unfavorable karyotype, 2.9 (2.0-4.2) for DIPSS high and 1.7 (1.4-2.2) for DIPSS intermediate-2. These observations were further confirmed by analysis of more stringently matched case-control subset cohorts and provide the evidence for the therapeutic preference of HCT in cytogenetically high risk patients with MF.

The 2016 WHO classification and diagnostic criteria for myeloproliferative neoplasms: document summary and in-depth discussion

The new edition of the 2016 World Health Organization (WHO) classification system for tumors of the hematopoietic and lymphoid tissues was published in September 2017. Under the category of myeloproliferative neoplasms (MPNs), the revised document includes seven subcategories: chronic myeloid leukemia, chronic neutrophilic leukemia, polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET), chronic eosinophilic leukemia-not otherwise specified and MPN, unclassifiable (MPN-U); of note, mastocytosis is no longer classified under the MPN category. In the current review, we focus on the diagnostic criteria for JAK2/CALR/MPL mutation-related MPNs: PV, ET, and PMF. In this regard, the 2016 changes were aimed at facilitating the distinction between masked PV and JAK2-mutated ET and between prefibrotic/early and overtly fibrotic PMF. In the current communication, we (i) provide practically useful resource tables and graphs on the new diagnostic criteria including outcome, (ii) elaborate on the rationale for the 2016 changes, (iii) discuss the complementary role of mutation screening, (iv) address ongoing controversies and propose solutions, (v) attend to the challenges of applying WHO criteria in routine clinical practice, and (vi) outline future directions from the perspectives of the clinical pathologist.

The 2016 WHO classification and diagnostic criteria for myeloproliferative neoplasms: document summary and in-depth discussion

The new edition of the 2016 World Health Organization (WHO) classification system for tumors of the hematopoietic and lymphoid tissues was published in September 2017. Under the category of myeloproliferative neoplasms (MPNs), the revised document includes seven subcategories: chronic myeloid leukemia, chronic neutrophilic leukemia, polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET), chronic eosinophilic leukemia-not otherwise specified and MPN, unclassifiable (MPN-U); of note, mastocytosis is no longer classified under the MPN category. In the current review, we focus on the diagnostic criteria for JAK2/CALR/MPL mutation-related MPNs: PV, ET, and PMF. In this regard, the 2016 changes were aimed at facilitating the distinction between masked PV and JAK2-mutated ET and between prefibrotic/early and overtly fibrotic PMF. In the current communication, we (i) provide practically useful resource tables and graphs on the new diagnostic criteria including outcome, (ii) elaborate on the rationale for the 2016 changes, (iii) discuss the complementary role of mutation screening, (iv) address ongoing controversies and propose solutions, (v) attend to the challenges of applying WHO criteria in routine clinical practice, and (vi) outline future directions from the perspectives of the clinical pathologist.

Molecular approaches identify a cryptic MECOM rearrangement in a child with a rapidly progressive myeloid neoplasm

Myeloid neoplasms are a heterogeneous group of hematologic disorders with divergent patterns of cell differentiation and proliferation, as well as divergent clinical courses. Rare recurrent genetic abnormalities related to this group of cancers are associated with poor outcomes. One such abnormality is the MECOM gene rearrangement that typically occurs in cases with chromosome 7 abnormalities. MECOM encodes a transcription factor that plays an essential role in cell proliferation and maintenance and also in epigenetic regulation. Aberrant expression of this gene is associated with reduced survival. Hence, its detailed characterization provides biological and clinical information relevant to the management of pediatric myeloid neoplasms. In this work, we describe a rare karyotype harboring three copies of MECOM with overexpression of the gene in a child with a very aggressive myeloid neoplasm. Cytogenetic studies defined the karyotype as 46,XX,der(7)t(3;7)(q26.2;q21.2). Array comparative genomic hybridization (aCGH) revealed a gain of 26.04 Mb in the 3q26.2-3qter region and a loss of 66.6 Mb in the 7q21.2-7qter region. RT-qPCR analysis detected elevated expression of the MECOM and CDK6 genes (458.5-fold and 35.2-fold, respectively). Overall, we show the importance of performing detailed molecular cytogenetic analysis of MECOM to enable appropriate management of high-risk pediatric myeloid neoplasms.

Changes in the World Health Organization 2016 classification of myeloid neoplasms everyone should know

PURPOSE OF REVIEW

This review highlights the main changes in the revised 2016 WHO classification of myeloid neoplasms (published in 2017) that impact diagnosis and ultimately impact management of patients with these diseases.

RECENT FINDINGS

The revision was based on data accumulated since the 2008 WHO classification, much of which relate to new molecular genetic information about these neoplasms. This massive recent influx of data concerning the significance of pathogenic mutations has affected all myeloid neoplasm categories. The new information has been incorporated as part of the diagnostic criteria of many diseases and has led to the creation of new provisional entities defined by genetic features. Germline mutations that predispose to myeloid neoplasms are also emerging as important findings that impact disease classification.

SUMMARY

The growing body of genetic data have not only altered the classification of myeloid neoplasms, but are also impacting patient management. Genetically-defined disease categories have characteristic prognoses and predicted clinical behavior. Some mutations are associated with responsiveness to certain therapies, including those that target relevant oncogenes. The disease categories in the new classification facilitate the application of risk-adapted therapy based on the most recently available data.

Gender and survival in essential thrombocythemia: A two-center study of 1,494 patients

Based on suggestive information from recent epidemiologic data and earlier retrospective studies, we revisited the effect of gender on survival in 1,494 patients with essential thrombocythemia (ET). The primary study population included 904 patients from the Mayo Clinic (median age 58 years; 65% females); risk distribution, according to the international prognostic score for ET (IPSET), was 23% high, 42% intermediate and 35% low. Multivariable analysis that included IPSET-relevant risk factors identified male sex (HR 1.6, 95% CI 1.3-2.0), age ≥60 years (HR 4.3, 95% CI 3.4-5.4) and leukocyte count ≥11 × 10(9)/L (HR 1.5, 95% CI 1.3-1.9) as independent predictors of shortened survival. These findings were confirmed by analysis of a separate cohort of 590 ET patients (65% females) from the University of Florence, Italy, with corresponding HRs (95% CI) of 1.6 (1.1-2.5), 4.6 (2.2-9.5) and 1.8 (1.1-2.8). The independent prognostic effect of gender was further corroborated by a separate multivariable analysis against IPSET risk categories; HR (95% CI) for the Mayo Clinic/Florence cohorts were 1.5/1.6 (1.2/1.1-1.8/2.5) for male sex, 6.8/7.5 (5.0/3.1-9.3/18.3) for IPSET high risk and 2.8/4.1 (2.1/1.8-3.8/9.5) for IPSET intermediate risk. Furthermore, the survival disadvantage in men was most apparent in IPSET high risk category and in patients older than 60 years. In both patient cohorts, thrombosis history garnered significance in univariate, but not in multivariable analysis. The observations from the current study suggest that women with ET live longer than their male counterparts and that gender might supersede thrombosis history as a risk variable for overall survival.

Pre-fibrotic/early primary myelofibrosis vs. WHO-defined essential thrombocythemia: The impact of minor clinical diagnostic criteria on the outcome of the disease

The 2016 revised WHO criteria for the diagnosis of pre-fibrotic/early primary myelofibrosis (pre-PMF) require at least one of the following four borderline expressed minor clinical criteria: anemia, leukocytosis, elevated lactate dehydrogenase and splenomegaly. In this study, we evaluated the relative frequency of these four criteria in a group of 170 pre-PMF patients and compared them to 225 ET cases. More than 91% of pre-PMF cases showed one or more of these features required for diagnosis, by contrast with only 48% of ET patients. According to clinical data the cumulative risk of progression to advanced/overt PMF in pre-PMF was 36.9% after 15 years. After fitting cox regression models to analyze the impact of the minor criteria on overall survival, only leukocytosis remained as a significant predictor of survival in both pre-PMF and ET. Molecular characterization showed differences in survival in pre-PMF but not ET, with CALR being a more favorable mutation than JAK2. The different outcome of pre-PMF versus ET and associated molecular genetic data supports the concept of two different entities, rather than a continuum of the same disease. Although slightly less than 50% of ET patients also show one or more minor clinical criteria, accurate distinction between ET and pre-PMF is possible by following an integrated approach including histomorphological diagnosis and presence of minor clinical criteria.

Fibroblast dynamics as an in vitro screening platform for anti-fibrotic drugs in primary myelofibrosis

Although the cause for bone marrow fibrosis in patients with myelofibrosis remains controversial, it has been hypothesized that it is caused by extensive fibroblast proliferation under the influence of cytokines generated by the malignant megakaryocytes. Moreover, there is no known drug therapy which could reverse the process. We studied the fibroblasts in a novel system using the hanging drop method, evaluated whether the fibroblasts obtain from patients are part of the malignant clone of not and, using this system, we screen a large library of FDA-approved drugs to identify potential drugs candidates that might be useful in the treatment of this disease, specifically which would inhibit fibroblast proliferation and the development of bone marrow fibrosis. We have found that the BM fibroblasts are not part of the malignant clone, as previously suspected and two immunosuppressive medications-cyclosporine and mycophenolate mophetil, as most potent suppressors of the fibroblast collagen production thus potentially inhibitors of bone marrow fibrosis production in myelofibrosis.

The prognostic relevance of serum lactate dehydrogenase and mild bone marrow reticulin fibrosis in essential thrombocythemia

The 2016 World Health Organization (WHO) diagnostic criteria for myeloproliferative neoplasms (MPN) underscore the prognostically-relevant distinction between essential thrombocythemia (ET) and prefibrotic primary myelofibrosis (pre-PMF). In addition, leukocytosis has been identified as an important prognostic marker in otherwise WHO-defined ET. However, controversy remains regarding the objectivity of morphologic criteria in distinguishing ET from pre-PMF and the precise prognostic cutoff values for leukocytosis. Serum lactate dehydrogenase (LDH) level might be a biologically more accurate measure of leukocyte turnover and a more sensitive marker of pre-PMF, in otherwise WHO-defined ET. In the current study of 183 consecutive patients with WHO-defined ET, the presence of grade 1 bone marrow (BM) fibrosis did not affect presenting clinical or laboratory features; in contrast, increased serum LDH at diagnosis was associated with leukocytosis (p = .002), thrombocytosis (p < .001), palpable splenomegaly (p = .03) and higher international prognostic score (IPSET) (p = .002); serum LDH did not correlate with BM fibrosis, JAK2/CALR/MPL or TET2/ASXL1 mutations. In univariate analysis, risk factors for survival included age ≥60 years (p = .002; HR 10.2, 95% CI 2.3-44.6), male sex (p = .02; HR 3.2, 95% CI 1.2-8.2), leukocyte count ≥15 × 10⁹ /L (p = .007; HR 4.7, 95% CI 1.5-14.6), and increased serum LDH (p = .002; HR 3.7, 95% CI 1.5-9.1), but not BM fibrosis (p = .17). In multivariable analysis, age, sex and serum LDH remained significant; serum LDH also remained significant, in the context of IPSET (p = .003) and in patients with leukocytosis (p = .003). We conclude that serum LDH level carries an independent prognostic value for survival in ET and might represent a biologically more accurate surrogate for leukocytosis.

Molecular testing for JAK2, MPL, and CALR in myeloproliferative neoplasms

Polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are myeloproliferative neoplasms characterized by recurrent somatic mutations in JAK2, CALR, and MPL. This short review addresses (1) the spectrum of mutations seen in PV, ET, and PMF, (2) the emerging genotype-phenotype correlations, (3) the current role of molecular testing in disease classification and management, and (4) several important considerations for selecting an appropriate molecular test. In our view, sequential testing algorithms and simultaneous assessment of multiple mutations by next-generation sequencing are both valid approaches to testing. Am. J. Hematol. 91:1277-1280, 2016. © 2016 Wiley Periodicals, Inc.

The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia

The World Health Organization (WHO) classification of tumors of the hematopoietic and lymphoid tissues was last updated in 2008. Since then, there have been numerous advances in the identification of unique biomarkers associated with some myeloid neoplasms and acute leukemias, largely derived from gene expression analysis and next-generation sequencing that can significantly improve the diagnostic criteria as well as the prognostic relevance of entities currently included in the WHO classification and that also suggest new entities that should be added. Therefore, there is a clear need for a revision to the current classification. The revisions to the categories of myeloid neoplasms and acute leukemia will be published in a monograph in 2016 and reflect a consensus of opinion of hematopathologists, hematologists, oncologists, and geneticists. The 2016 edition represents a revision of the prior classification rather than an entirely new classification and attempts to incorporate new clinical, prognostic, morphologic, immunophenotypic, and genetic data that have emerged since the last edition. The major changes in the classification and their rationale are presented here.