Interferon alfa therapy in CALR-mutated essential thrombocythemia

Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management

OVERVIEW

Essential thrombocythemia is a Janus kinase 2 (JAK2) mutation-prevalent myeloproliferative neoplasm characterized by clonal thrombocytosis; clinical course is often indolent but might be interrupted by thrombotic or hemorrhagic complications, microcirculatory symptoms (e.g., headaches, lightheadedness, and acral paresthesias), and, less frequently, by disease transformation into myelofibrosis (MF) or acute myeloid leukemia.

DIAGNOSIS

In addition to thrombocytosis (platelets ≥450 × 109 /L), formal diagnosis requires the exclusion of other myeloid neoplasms, including prefibrotic MF, polycythemia vera, chronic myeloid leukemia, and myelodysplastic syndromes with ring sideroblasts and thrombocytosis. Bone marrow morphology typically shows increased number of mature-appearing megakaryocytes distributed in loose clusters.

GENETICS

Approximately 80% of patients express myeloproliferative neoplasm driver mutations (JAK2, CALR, MPL), in a mutually exclusive manner; in addition, about 50% harbor other mutations, the most frequent being TET2 (9%-11%), ASXL1 (7%-20%), DNMT3A (7%), and SF3B1 (5%). Abnormal karyotype is seen in <10% of patients and includes +9/20q-/13q-.

SURVIVAL AND PROGNOSIS

Life expectancy is less than that of the control population. Median survival is approximately 18 years but exceeds >35 years in younger patients. The triple A survival risk model, based on Age, Absolute neutrophil count, and Absolute lymphocyte count, effectively delineates high-, intermediate-1-, intermediate-2-, and low-risk disease with corresponding median survivals of 8, 14, 21, and 47 years.

RISK FACTORS FOR THROMBOSIS

Four risk categories are considered: very low (age ≤60 years, no thrombosis history, JAK2 wild-type), low (same as very low but JAK2 mutation present), intermediate (same as low but age >60 years), and high (thrombosis history or age >60 years with JAK2 mutation).

MUTATIONS AND PROGNOSIS

MPL and CALR-1 mutations have been associated with increased risk of MF transformation; spliceosome with inferior overall and MF-free survival; TP53 with leukemic transformation, and JAK2V617F with thrombosis. Leukemic transformation rate at 10 years is <1% but might be higher in JAK2-mutated patients with extreme thrombocytosis and those with abnormal karyotype.

TREATMENT

The main goal of therapy is to prevent thrombosis. In this regard, once-daily low-dose aspirin is advised for all patients and twice daily for low-risk disease. Cytoreductive therapy is advised for high-risk and optional for intermediate-risk disease. First-line cytoreductive drugs of choice are hydroxyurea and pegylated interferon-α and second-line busulfan.

ADDITIONAL CONTENT

The current review includes specific treatment strategies in the context of extreme thrombocytosis, pregnancy, splanchnic vein thrombosis, perioperative care, and post-essential thrombocythemia MF, as well as new investigational drugs.

Ratio of stemness to interferon signalling as a biomarker and therapeutic target of myeloproliferative neoplasm progression to acute myeloid leukaemia

Progression to aggressive secondary acute myeloid leukaemia (sAML) poses a significant challenge in the management of myeloproliferative neoplasms (MPNs). Since the physiopathology of MPN is closely linked to the activation of interferon (IFN) signalling and that AML initiation and aggressiveness is driven by leukaemia stem cells (LSCs), we investigated these pathways in MPN to sAML progression. We found that high IFN signalling correlated with low LSC signalling in MPN and AML samples, while MPN progression and AML transformation were characterized by decreased IFN signalling and increased LSC signature. A high LSC to IFN expression ratio in MPN patients was associated with adverse clinical prognosis and higher colony forming potential. Moreover, treatment with hypomethylating agents (HMAs) activates the IFN signalling pathway in MPN cells by inducing a viral mimicry response. This response is characterized by double-stranded RNA (dsRNA) formation and MDA5/RIG-I activation. The HMA-induced IFN response leads to a reduction in LSC signature, resulting in decreased stemness. These findings reveal the frequent evasion of viral mimicry during MPN-to-sAML progression, establish the LSC-to-IFN expression ratio as a progression biomarker, and suggests that HMAs treatment can lead to haematological response in murine models by re-activating dsRNA-associated IFN signalling.

The molecular landscape of myeloproliferative neoplasms associated with splanchnic vein thrombosis: Current perspective

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are classically represented by polycythemia vera, essential thrombocythemia, and primary myelofibrosis. BCR::ABL1-negative MPNs are significantly associated with morbidity and mortality related to an increased risk of thrombo-hemorrhagic events. They show a consistent association with splanchnic vein thrombosis (SVT), either represented by the portal, mesenteric or splenic vein thrombosis, or Budd-Chiari Syndrome. SVT is also a frequent presenting manifestation of MPN. MPNs associated with SVT show a predilection for younger women, high association with JAK2V617F mutation, low JAK2V617F variant allele frequency (generally <10 %), and low rates of CALR, MPL, or JAK2 exon 12 mutations. Next-Generation Sequencing techniques have contributed to deepening our knowledge of the molecular landscape of such cases, with potential diagnostic and prognostic implications. In this narrative review, we analyze the current perspective on the molecular background of MPN associated with SVT, pointing as well future directions in this field.

Clonal architecture evolution in Myeloproliferative Neoplasms: from a driver mutation to a complex heterogeneous mutational and phenotypic landscape

Myeloproliferative neoplasms are characterized by the acquisition at the hematopoietic stem cell level of driver mutations targeting the JAK/STAT pathway. In addition, they also often exhibit additional mutations targeting various pathways such as intracellular signalling, epigenetics, mRNA splicing or transcription. The natural history of myeloproliferative neoplasms is usually marked by a chronic phase of variable duration depending on the disease subtype, which can be followed by an accelerated phase or transformation towards more aggressive diseases such as myelofibrosis or acute leukemia. Besides, recent studies revealed important new information about the rates and mechanisms of sequential acquisition and selection of mutations in hematopoietic cells of myeloproliferative neoplasms. Better understanding of these events has been made possible in large part with the help of novel techniques that are now available to precisely decipher at the single cell level both the clonal architecture and the mutation-induced cell modifications. In this review, we will summarize the most recent knowledge about the mechanisms leading to clonal selection, how clonal architecture complexity can explain disease heterogeneity, and the impact of clonal evolution on clinical evolution.

Inferring the dynamics of mutated hematopoietic stem and progenitor cells induced by IFNα in myeloproliferative neoplasms

Classical BCR-ABL-negative myeloproliferative neoplasms (MPNs) are clonal disorders of hematopoietic stem cells (HSCs) caused mainly by recurrent mutations in genes encoding JAK2 (JAK2), calreticulin (CALR), or the thrombopoietin receptor (MPL). Interferon α (IFNα) has demonstrated some efficacy in inducing molecular remission in MPNs. To determine factors that influence molecular response rate, we evaluated the long-term molecular efficacy of IFNα in patients with MPN by monitoring the fate of cells carrying driver mutations in a prospective observational and longitudinal study of 48 patients over more than 5 years. We measured the clonal architecture of early and late hematopoietic progenitors (84 845 measurements) and the global variant allele frequency in mature cells (409 measurements) several times per year. Using mathematical modeling and hierarchical Bayesian inference, we further inferred the dynamics of IFNα-targeted mutated HSCs. Our data support the hypothesis that IFNα targets JAK2V617F HSCs by inducing their exit from quiescence and differentiation into progenitors. Our observations indicate that treatment efficacy is higher in homozygous than heterozygous JAK2V617F HSCs and increases with high IFNα dose in heterozygous JAK2V617F HSCs. We also found that the molecular responses of CALRm HSCs to IFNα were heterogeneous, varying between type 1 and type 2 CALRm, and a high dose of IFNα correlates with worse outcomes. Our work indicates that the long-term molecular efficacy of IFNα implies an HSC exhaustion mechanism and depends on both the driver mutation type and IFNα dose.

Clinical outcomes of interferon therapy for polycythemia vera and essential thrombocythemia: a systematic review and meta-analysis

Interferon therapy has been used in clinical practice for more than three decades to treat polycythemia vera (PV) and essential thrombocythemia (ET). However, there has been no systematic investigation of its expected outcomes and potential risks. We performed a systematic review and single-arm meta-analysis to assess the clinical outcomes (hematological response, molecular response, vascular events, hematological transformation, and adverse events) after interferon therapy for patients with PV and ET. A systematic search identified 37 reports, including data from 1794 patients that were published before March 2021. The pooled overall hematological response (OHR) rate was 86%, with better OHR rates observed in studies using long-acting interferon (p < 0.001) and studies with younger patients (p = 0.038). The pooled overall molecular response rate was 48%, and inter-study heterogeneity was also related to patient age (p = 0.009). The overall incidence was 0.42/100 person-years for thrombosis, 0.01/100 person-years for hemorrhage, 0.21/100 person-years for myelofibrotic transformation, and 0.08/100 person-years for leukemic transformation. Compared with hydroxyurea, interferon produced a non-inferior hematological response and a superior molecular response. In conclusion, interferon therapy provided high rates of hematological and molecular response for patients with PV and ET and was associated with a favorable prognosis.

Prevention and Management of Thrombosis in BCR/ABL-Negative Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are clonal disorders of the hematopoietic stem cell. Classical BCR/ABL-negative MPNs include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Thrombotic events are a major cause of morbidity and mortality in these patients. Pathogenesis of blood clotting activation involves various abnormalities of platelets, erythrocytes, and leukocytes, as well as dysfunctions of endothelial cells. Patients with MPN can be stratified in "high risk" or "low risk" of thrombosis according to established risk factors. ET and PV clinical management is highly dependent on the patient's thrombotic risk, and a risk-oriented management strategy to treat these diseases is strongly recommended. In this review, we give an overview of risk factors, pathogenesis, and thrombosis prevention and treatment in MPN.

Myeloproliferative neoplasms treated with hydroxyurea, pegylated interferon alpha-2A or ruxolitinib: clinicohematologic responses, quality-of-life changes and safety in the real-world setting

Introduction: Real-world data of responses, quality-of-life (QOL) changes and adverse events in patients with myeloproliferative neoplasms (MPN) on conventional therapy (hydroxyurea ± anagrelide), pegylated interferon alpha-2A (PEG-IFNα-2A) or ruxolitinib are limited. Methods: We prospectively studied MPN patients receiving conventional therapy, PEG-IFNα-2A or ruxolitinib. Next-generation sequencing of 69 myeloid-related genes was performed. Clinicohematologic responses, adverse events, and QOL (determined by the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score, MPN-SAF TSS) were evaluated. Results: Seventy men and fifty-five women with polycythemia vera (PV) (N = 23), essential thrombocythemia (ET) (N = 56) and myelofibrosis (MF) (N = 46) were studied for a median of 36 (range: 19-42) months. In PV, responses were comparable for different modalities. CREBBP mutations were associated with inferior responses. In ET, PEG-IFNα-2A resulted in superior clinicohematologic complete responses (CHCR) (P = 0.045). In MF, superior overall response rates (ORR) were associated with ruxolintib (P = 0.018) and JAK2V617F mutation (P = 0.04). For the whole cohort, ruxolitinib led to rapid and sustained reduction in spleen size within the first 6 months, and significant improvement of QOL as reflected by reduction in MPN-SAF TSS (P < 0.001). Adverse events of grades 1-2 were observed in 44%, 62% and 20% of patients receiving conventional therapy, PEG-IFNα-2A and ruxolitinib respectively; and of grade 3-4 in 7% and 9% of patients receiving PEG-IFNα-2A and ruxolitinib. Conclusions: Conventional therapy, PEG-IFNα-2A and ruxolitinib induced responses in all MPN subtypes. PEG-IFNα-2A led to superior CHCR in ET; whereas ruxolitinib resulted in superior ORR in MF, and significant reduction in spleen size and improvement in QOL.

Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPN) respectively characterized by clonal erythrocytosis and thrombocytosis; other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus and risk of leukemic or fibrotic transformation.

DIAGNOSIS

Bone marrow morphology remains the cornerstone of diagnosis. In addition, the presence of JAK2 mutation is expected in PV while approximately 90% of patients with ET express mutually exclusive JAK2, CALR or MPL mutations (so called driver mutations). In ET, it is most important to exclude the possibility of prefibrotic myelofibrosis.

SURVIVAL

Median survivals are approximately 15 years for PV and 18 years for ET; the corresponding values for patients age 40 or younger were 37 and 35 years. Certain mutations (mostly spliceosome) and abnormal karyotype might compromise survival in PV and ET. Life-expectancy in ET is inferior to the control population. Driver mutations have not been shown to affect survival in ET but risk of thrombosis is higher in JAK2 mutated cases. Leukemic transformation rates at 10 years are estimated at <1% for ET and 3% for PV.

THROMBOSIS RISK

In PV, two risk categories are considered: high (age > 60 years or thrombosis history present) and low (absence of both risk factors). In ET, four risk categories are considered: very low (age ≤ 60 years, no thrombosis history, JAK2 wild-type), low (same as very low but JAK2 mutation present), intermediate (age > 60 years, no thrombosis history, JAK2 wild-type) and high (thrombosis history present or age > 60 years with JAK2 mutation).

RISK-ADAPTED THERAPY

The main goal of therapy in both PV and ET is to prevent thrombohemorrhagic complications. All patients with PV require phlebotomy to keep hematocrit below 45% and once-daily or twice-daily aspirin (81 mg), in the absence of contraindications. Very low risk ET might not require therapy while aspirin therapy is advised for low risk disease. Cytoreductive therapy is recommended for high-risk ET and PV, but it is not mandatory for intermediate-risk ET. First-line drug of choice for cytoreductive therapy, in both ET and PV, is hydroxyurea and second-line drugs of choice are interferon-α and busulfan. We do not recommend treatment with ruxolutinib in PV, unless in the presence of severe and protracted pruritus or marked splenomegaly that is not responding to the aforementioned drugs.

NEW TREATMENT DIRECTIONS

Controlled studies are needed to confirm the clinical outcome value of twice-daily vs once-daily aspirin dosing and the therapeutic role of pegylated interferons and direct oral anticoagulants.

Clonal Hematopoiesis and Mutations of Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are associated with the fewest number of mutations among known cancers. The mutations propelling these malignancies are phenotypic drivers providing an important implement for diagnosis, treatment response monitoring, and gaining insight into the disease biology. The phenotypic drivers of Philadelphia chromosome negative MPN include mutations in JAK2, CALR, and MPL. The most prevalent driver mutation JAK2V617F can cause disease entities such as essential thrombocythemia (ET) and polycythemia vera (PV). The divergent development is considered to be influenced by the acquisition order of the phenotypic driver mutation relative to other MPN-related mutations such as TET2 and DNMT3A. Advances in molecular biology revealed emergence of clonal hematopoiesis (CH) to be inevitable with aging and associated with risk factors beyond the development of blood cancers. In addition to its well-established role in thrombosis, the JAK2V617F mutation is particularly connected to the risk of developing cardiovascular disease (CVD), a pertinent issue, as deep molecular screening has revealed the prevalence of the mutation to be much higher in the background population than previously anticipated. Recent findings suggest a profound under-diagnosis of MPNs, and considering the impact of CVD on society, this calls for early detection of phenotypic driver mutations and clinical intervention.

Use of Interferon Alfa in the Treatment of Myeloproliferative Neoplasms: Perspectives and Review of the Literature

Interferon alfa was first used in the treatment of myeloproliferative neoplasms (MPNs) over 30 years ago. However, its initial use was hampered by its side effect profile and lack of official regulatory approval for MPN treatment. Recently, there has been renewed interest in the use of interferon in MPNs, given its potential disease-modifying effects, with associated molecular and histopathological responses. The development of pegylated formulations and, more recently, ropeginterferon alfa-2b has resulted in improved tolerability and further expansion of interferon's use. We review the evolving clinical use of interferon in essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis (MF). We discuss interferon's place in MPN treatment in the context of the most recent clinical trial results evaluating interferon and its pegylated formulations, and its role in special populations such as young and pregnant MPN patients. Interferon has re-emerged as an important option in MPN patients, with future studies seeking to re-establish its place in the existing treatment algorithm for MPN, and potentially expanding its use for novel indications and combination therapies.

Cancer Immune Therapy for Philadelphia Chromosome-Negative Chronic Myeloproliferative Neoplasms

Philadelphia chromosome-negative chronic myeloproliferative neoplasms (MPN) are neoplastic diseases of the hematopoietic stem cells in the bone marrow. MPN are characterized by chronic inflammation and immune dysregulation. Of interest, the potent immunostimulatory cytokine interferon-α has been used to treat MPN for decades. A deeper understanding of the anti-cancer immune response and of the different immune regulatory mechanisms in patients with MPN has paved the way for an increased perception of the potential of cancer immunotherapy in MPN. Therapeutic vaccination targeting the driver mutations in MPN is one recently described potential new treatment modality. Furthermore, T cells can directly react against regulatory immune cells because they recognize proteins like arginase and programmed death ligand 1 (PD-L1). Therapeutic vaccination with arginase or PD-L1 therefore offers a novel way to directly affect immune inhibitory pathways, potentially altering tolerance to tumor antigens like mutant CALR and mutant JAK2. Other therapeutic options that could be used in concert with therapeutic cancer vaccines are immune checkpoint-blocking antibodies and interferon-α. For more advanced MPN, adoptive cellular therapy is a potential option that needs more preclinical investigation. In this review, we summarize current knowledge about the immune system in MPN and discuss the many opportunities for anti-cancer immunotherapy in patients with MPN.

Interferon Alpha Therapy Increases Pro-Thrombotic Biomarkers in Patients with Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPN) are associated with an increased risk of arterial and venous thrombosis. Pegylated-interferon alpha (IFN) and hydroxyurea (HU) are commonly used to treat MPN, but their effect on hemostasis has not yet been studied. The aim of our study was to determine whether IFN and HU impact the biological hemostatic profile of MPN patients by studying markers of endothelial, platelet, and coagulation activation. A total of 85 patients (50 polycythemia vera and 35 essential thrombocythemia) were included: 28 treated with IFN, 35 with HU, and 22 with no cytoreductive drug (non-treated, NT). Von Willebrand factor, shear-induced platelet aggregation, factor VIII coagulant activity (FVIII:C), fibrinogen, and thrombin generation with and without exogenous thrombomodulin were significantly higher in IFN-treated patients compared to NT patients, while protein S anticoagulant activity was lower. In 10 patients in whom IFN therapy was discontinued, these hemostatic biomarkers returned to the values observed in NT patients, strongly suggesting an impact of IFN therapy on endothelial and coagulation activation. Overall, our study shows that treatment with IFN is associated with significant and reversible effects on the biological hemostatic profile of MPN patients. Whether they could be associated with an increased thrombotic risk remains to be determined in further randomized clinical studies.

Emerging translational science discoveries, clonal approaches, and treatment trends in chronic myeloproliferative neoplasms

The 60th American Society of Hematology (ASH) held in San Diego in December 2018 was followed by the 13th Post-ASH chronic myeloproliferative neoplasms (MPNs) workshop on December 4 and 5, 2018. This closed annual workshop, first introduced in 2006 by Goldman and Mughal, was organized in collaboration with Alpine Oncology Foundation and allowed experts in preclinical and clinical research in the chronic MPNs to discuss the current scenario, including relevant presentations at ASH, and address pivotal open questions that impact translational research and clinical management. This review is based on the presentations and deliberations at this workshop, and rather than provide a resume of the proceedings, we have selected some of the important translational science and treatment issues that require clarity. We discuss the experimental and observational evidence to support the intimate interaction between aging, inflammation, and clonal evolution of MPNs, the clinical impact of the unfolding mutational landscape on the emerging targets and treatment of MPNs, new methods to detect clonal heterogeneity, the challenges in managing childhood and adolescent MPN, and reflect on the treatment of systemic mastocytosis (SM) following the licensing of midostaurin.

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.

Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk-stratification and management

Disease Overview: Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms respectively characterized by erythrocytosis and thrombocytosis; other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus, and risk of leukemic or fibrotic transformation. Diagnosis: Bone marrow morphology remains the cornerstone of diagnosis. In addition, the presence of JAK2 mutation is expected in PV while approximately 90% of patients with ET express mutually exclusive JAK2, CALR, or myeloproliferative leukemia mutations. In ET, it is most important to exclude the possibility of prefibrotic myelofibrosis. Survival: Median survivals are 14 years for PV and 20 years for ET; the corresponding values for younger patients are 24 and 33 years. Certain mutations (mostly spliceosome) and abnormal karyotype might compromise survival in PV and ET. Life-expectancy in ET is inferior to the control population. Driver mutations have not been shown to affect survival in ET. Risk of thrombosis is higher in JAK2-mutated ET. Leukemic transformation rates at 10 years are estimated at <1% for ET and 3% for PV. Thrombosis Risk: In PV, 2 risk categories are considered: high (age > 60 years or thrombosis history present) and low (absence of both risk factors); in ET, 4 risk categories are considered: very low (age ≤ 60 years, no thrombosis history, JAK2 wild-type), low (same as very low but JAK2 mutation present), intermediate (age > 60 years, no thrombosis history, JAK2 wild-type) and high (thrombosis history present or age > 60 years with JAK2 mutation). Risk-Adapted Therapy: The main goal of therapy in both PV and ET is to prevent thrombohemorrhagic complications. All patients with PV require phlebotomy to keep hematocrit below 45% and once- or twice-daily aspirin (81 mg), in the absence of contraindications. Very low-risk ET might not require therapy while aspirin therapy is advised for low-risk disease. Cytoreductive therapy is recommended for high-risk ET and PV but it is not mandatory for intermediate-risk ET. First-line drug of choice for cytoreductive therapy, in both ET and PV, is hydroxyurea and second-line drugs of choice are interferon-α and busulfan. We do not recommend treatment with ruxolutinib in PV, unless in the presence of severe and protracted pruritus or marked splenomegaly that is not responding to the aforementioned drugs.

JAK2V617F but not CALR mutations confer increased molecular responses to interferon-α via JAK1/STAT1 activation

Pegylated interferon-α (peg-IFNa) treatment induces molecular responses (MR) in patients with myeloproliferative neoplasms (MPNs), including partial MR (PMR) in 30-40% of patients. Here, we compared the efficacy of IFNa treatment in JAK2V617F- vs. calreticulin (CALR)-mutated cells and investigated the mechanisms of differential response. Retrospective analysis of MPN patients treated with peg-IFNa demonstrated that patients harboring the JAK2V617F mutation were more likely to achieve PMR than those with mutated CALR (p = 0.004), while there was no significant difference in hematological response. In vitro experiments confirmed an upregulation of IFN-stimulated genes in JAK2V617F-positive 32D cells as well as patient samples (peripheral blood mononuclear cells and CD34+ hematopoietic stem cells) compared to their CALR-mutated counterparts, and higher IFNa doses were needed to achieve the same IFNa response in CALR- as in JAK2V617F-mutant 32D cells. Additionally, Janus-activated kinase-1 (JAK1) and signal transducers and activators of transcription 1 (STAT1) showed constitutive phosphorylation in JAK2V617F-mutated but not CALR-mutated cells, indicating priming towards an IFNa response. Moreover, IFN-induced growth arrest was counteracted by selective JAK1 inhibition but enhanced by JAK2 inhibition. In conclusion, our data suggest that, clinically, higher doses of IFNa are needed in CALR-mutated vs. JAK2V617F-positive patients and we suggest a model of JAK2V617F-JAK1/STAT1 crosstalk leading to a priming of JAK2V617F-positive cells to IFNa resulting in differential sensitivity.

Splanchnic vein thrombosis in myeloproliferative neoplasms: treatment algorithm 2018

Myeloproliferative neoplasms (MPNs) are a leading cause of splanchnic vein thrombosis (SVT). SVT is observed in all MPNs and frequently affects young patients. Therapy should be addressed to three main goals: preventing thrombosis recurrence, managing the underlying MPN, and supporting liver dysfunction. Life-long oral anticoagulation with vitamin K antagonists is the cornerstone of the antithrombotic treatment. However, recurrences of SVT or other thrombosis may occur in 15-20% of patients. Direct oral anticoagulants can represent an alternative and preliminary data encourage comparative studies. Survival of patients with SVT in MPN is primarily influenced by the natural history of the underlying neoplasms, rather than the SVT event. An aggressive management is recommended and a treatment algorithm based on the different MPN subtypes is proposed. Hydroxyurea is the cytoreductive drug of choice in polycythemia vera and essential thrombocythemia, whereas ruxolitinib is indicated in intermediate and high-risk patients with myelofibrosis and in PV patients resistant or intolerant to hydroxyurea. The management of SVT in MPNs requires a multidisciplinary approach that may include a hematologist, a gastroenterologist, an interventional radiologist, and a surgeon. In the case of clinical deterioration despite pharmacological therapy, patients with SVT should be considered for invasive procedures or liver transplantation.

The Critical Role of Inflammation in the Pathogenesis and Progression of Myeloid Malignancies

Hematopoietic stem cells (HSCs) maintain an organism's immune system for a lifetime, and derangements in HSC proliferation and differentiation result in hematologic malignancies. Chronic inflammation plays a contributory if not causal role in HSC dysfunction. Inflammation induces HSC exhaustion, which promotes the emergence of mutant clones that may be resistant to an inflammatory microenvironment; this likely promotes the onset of a myeloid hematologic malignancy. Inflammatory cytokines are characteristically high in patients with myeloid malignancies and are linked to disease initiation, symptom burden, disease progression, and worsened prognostic survival. This review will cover our current understanding of the role of inflammation in the initiation, progression, and complications of myeloid hematologic malignancies, drawing from clinical studies as well as murine models. We will also highlight inflammation as a therapeutic target in hematologic malignancies.

Philadelphia chromosome-negative classical myeloproliferative neoplasms: revised management recommendations from European LeukemiaNet

This document updates the recommendations on the management of Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-neg MPNs) published in 2011 by the European LeukemiaNet (ELN) consortium. Recommendations were produced by multiple-step formalized procedures of group discussion. A critical appraisal of evidence by using Grades of Recommendation, Assessment, Development and Evaluation (GRADE) methodology was performed in the areas where at least one randomized clinical trial was published. Seven randomized controlled trials provided the evidence base; earlier phase trials also informed recommendation development. Key differences from the 2011 diagnostic recommendations included: lower threshold values for hemoglobin and hematocrit and bone marrow examination for diagnosis of polycythemia vera (PV), according to the revised WHO criteria; the search for complementary clonal markers, such as ASXL1, EZH2, IDH1/IDH2, and SRSF2 for the diagnosis of myelofibrosis (MF) in patients who test negative for JAK2V617, CALR or MPL driver mutations. Regarding key differences of therapy recommendations, both recombinant interferon alpha and the JAK1/JAK2 inhibitor ruxolitinib are recommended as second-line therapies for PV patients who are intolerant or have inadequate response to hydroxyurea. Ruxolitinib is recommended as first-line approach for MF-associated splenomegaly in patients with intermediate-2 or high-risk disease; in case of intermediate-1 disease, ruxolitinib is recommended in highly symptomatic splenomegaly. Allogeneic stem cell transplantation is recommended for transplant-eligible MF patients with high or intermediate-2 risk score. Allogeneic stem cell transplantation is also recommended for transplant-eligible MF patients with intermediate-1 risk score who present with either refractory, transfusion-dependent anemia, blasts in peripheral blood > 2%, adverse cytogenetics, or high-risk mutations. In these situations, the transplant procedure should be performed in a controlled setting.

The calreticulin (CALR) exon 9 mutations are promising targets for cancer immune therapy

The calreticulin (CALR) exon 9 mutations are found in ∼30% of patients with essential thrombocythemia and primary myelofibrosis. Recently, we reported spontaneous immune responses against the CALR mutations. Here, we describe that CALR-mutant (CALRmut)-specific T cells are able to specifically recognize CALRmut cells. First, we established a T-cell culture specific for a CALRmut epitope. These specific T cells were able to recognize several epitopes in the CALRmut C terminus. Next, we established a CALRmut-specific CD4⁺ T-cell clone by limiting dilution. These CD4⁺ T cells recognized autologous CALRmut monocytes and hematopoietic stem cells, and T-cell recognition of target cells was dependent on the presence of CALR. Furthermore, we showed that the CALRmut response was human leukocyte antigen (HLA)-DR restricted. Finally, we demonstrated that the CALRmut-specific CD4⁺ T cells, despite their phenotype, were cytotoxic to autologous CALRmut cells, and that the cytotoxicity was mediated by degranulation of the T cells. In conclusion, the CALR exon 9 mutations are targets for specific T cells and thus are promising targets for cancer immune therapy such as peptide vaccination in patients harboring CALR exon 9 mutations.

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.

A novel molecular assay using hybridisation probes and melt curve analysis for CALR exon 9 mutation detection in myeloproliferative neoplasms

AIMS

Somatic insertions/deletions in exon 9 of the calreticulin gene have been identified in patients with essential thrombocythemia and primary myelofibrosis. Over 55 mutations have been discovered, 80% of which consist of either type 1 52-bp deletion or type 2 5-bp insertion. Other mutations (types 3-5) in conjunction with types 1 and 2 account for >87% of identified mutations. The aim of this study was development of a rapid PCR-based assay using LightCycler Hybridisation Probes for the detection of type 1-5 CALR mutations.

METHOD

A real-time PCR assay using a novel HybProbe set was developed for use on the LightCycler 480 Instrument II. The acceptor probe was labelled with LC640 and Faststart DNA Master HybProbe kit was used for PCR reactions.

RESULTS

Assay limit of detection was determined to be seven target copies with a probability of 95%. The specificity of the assay was determined by using synthetic constructs of CALR wild-type and CALR mutation types 1-5 with no non-specific detection observed. Samples from 21 patients with essential thrombocythemia (ET) and 12 patients with primary myelofibrosis (PMF), together with 29 control samples from patients diagnosed with various conditions, were screened using the assay. Of these, 24 were found to have mutations in CALR exon 9, with the assay detecting 8 type 1 mutations, 12 type 2 mutations, 2 type 24 mutations, 1 type 20 mutation and 1 31-bp deletion.

CONCLUSIONS

The novel assay described has potential for application as a rapid, sensitive, high-throughput screening method in the clinical diagnostics setting.

Polycythemia vera and essential thrombocythemia: 2017 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Polycythemia Vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms respectively characterized by erythrocytosis and thrombocytosis; other disease features include leukocytosis, splenomegaly, thrombosis, bleeding, microcirculatory symptoms, pruritus, and risk of leukemic or fibrotic transformation.

DIAGNOSIS

PV is defined by a JAK2 mutation, whose absence, combined with normal or increased serum erythropoietin level, makes the diagnosis unlikely. JAK2, CALR, and MPL mutations are the mutually exclusive "driver" mutations in ET with respective incidences of 55%, 25%, and 3%; approximately 17% are triple-negative. However, the same molecular markers might also be present in prefibrotic myelofibrosis, whose morphological distinction from ET is prognostically relevant.

SURVIVAL AND LEUKEMIC/FIBROTIC TRANSFORMATION

Median survivals are approximately 14 years for PV and 20 years for ET; the corresponding values for younger patients (age <60 years) are 24 and 33 years. Life-expectancy in ET is inferior to the control population. Driver mutational status has not been shown to affect survival in ET whereas the presence of JAK2/MPL mutations has been associated with higher risk of arterial thrombosis and that of MPL with higher risk of fibrotic progression. Risk factors for overall survival in both ET and PV include advanced age, leukocytosis and thrombosis. Leukemic transformation rates at 20 years are estimated at <10% for PV and 5% for ET; fibrotic transformation rates are slightly higher. Most recently, ASXL1, SRSF2, and IDH2 mutations have been associated with inferior overall, leukemia-free or fibrosis-free survival in PV; similarly adverse mutations in ET included SH2B3, SF3B1, U2AF1, TP53, IDH2, and EZH2.

THROMBOSIS RISK STRATIFICATION

Current risk stratification in PV and ET is designed to estimate the likelihood of recurrent thrombosis. Accordingly, PV includes two risk categories: high-risk (age >60 years or thrombosis history) and low-risk (absence of both risk factors). In ET, risk stratification includes four categories: very low risk (age ≤60 years, no thrombosis history, JAK2/MPL un-mutated), low risk (age ≤60 years, no thrombosis history, JAK2/MPL mutated), intermediate risk (age >60 years, no thrombosis history, JAK2/MPL un-mutated), and high risk (thrombosis history or age >60 years with JAK2/MPL mutation). In addition, presence of extreme thrombocytosis (platelets >1000 × 10(9)/L) might be associated with acquired von Willebrand syndrome (AvWS) and, therefore, risk of bleeding.

RISK-ADAPTED THERAPY

The main goal of therapy in PV and ET is to prevent thrombohemorrhagic complications. All patients with PV require phlebotomy to keep hematocrit below 45% and once-daily aspirin (81 mg). In addition, high-risk patients with PV require cytoreductive therapy. Very low risk ET patients might not require any form of therapy while low-risk patients require at least once-daily aspirin therapy. Cytoreductive therapy is also recommended for high-risk ET patients but it is not mandatory for intermediate-risk patients. First-line drug of choice for cytoreductive therapy, in both ET and PV, is hydroxyurea and second-line drugs of choice are interferon-α and busulfan. We currently do not recommend treatment with ruxolutinib or other JAK2 inhibitors in PV or ET, unless in the presence of severe and protracted pruritus or marked splenomegaly that is not responding to the aforementioned drugs. Screening for AvWS is recommended before administrating aspirin, in the presence of extreme thrombocytosis. Am. J. Hematol. 92:95-108, 2017. © 2016 Wiley Periodicals, Inc.

Diagnosis, risk stratification, and response evaluation in classical myeloproliferative neoplasms

Philadelphia-negative classical myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The 2016 revision of the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues includes new criteria for the diagnosis of these disorders. Somatic mutations in the 3 driver genes, that is, JAK2, CALR, and MPL, represent major diagnostic criteria in combination with hematologic and morphological abnormalities. PV is characterized by erythrocytosis with suppressed endogenous erythropoietin production, bone marrow panmyelosis, and JAK2 mutation. Thrombocytosis, bone marrow megakaryocytic proliferation, and presence of JAK2, CALR, or MPL mutation are the main diagnostic criteria for ET. PMF is characterized by bone marrow megakaryocytic proliferation, reticulin and/or collagen fibrosis, and presence of JAK2, CALR, or MPL mutation. Prefibrotic myelofibrosis represents an early phase of myelofibrosis, and is characterized by granulocytic/megakaryocytic proliferation and lack of reticulin fibrosis in the bone marrow. The genomic landscape of MPNs is more complex than initially thought and involves several mutant genes beyond the 3 drivers. Comutated, myeloid tumor-suppressor genes contribute to phenotypic variability, phenotypic shifts, and progression to more aggressive disorders. Patients with myeloid neoplasms are at variable risk of vascular complications, including arterial or venous thrombosis and bleeding. Current prognostic models are mainly based on clinical and hematologic parameters, but innovative models that include genetic data are being developed for both clinical and trial settings. In perspective, molecular profiling of MPNs might also allow for accurate evaluation and monitoring of response to innovative drugs that target the mutant clone.

How I treat essential thrombocythemia

Essential thrombocythemia (ET) is an indolent myeloproliferative neoplasm that may be complicated by vascular events, including both thrombosis and bleeding. This disorder may also transform into more aggressive myeloid neoplasms, in particular into myelofibrosis. The identification of somatic mutations of JAK2, CALR, or MPL, found in about 90% of patients, has considerably improved the diagnostic approach to this disorder. Genomic profiling also holds the potential to improve prognostication and, more generally, clinical decision-making because the different driver mutations are associated with distinct clinical features. Prevention of vascular events has been so far the main objective of therapy, and continues to be extremely important in the management of patients with ET. Low-dose aspirin and cytoreductive drugs can be administered to this purpose, with cytoreductive treatment being primarily given to patients at high risk of vascular complications. Currently used cytoreductive drugs include hydroxyurea, mainly used in older patients, and interferon α, primarily given to younger patients. There is a need for disease-modifying drugs that can eradicate clonal hematopoiesis and/or prevent progression to more aggressive myeloid neoplasms, especially in younger patients. In this article, we use a case-based discussion format to illustrate our approach to diagnosis and treatment of ET.

New molecular genetics in the diagnosis and treatment of myeloproliferative neoplasms

PURPOSE OF REVIEW

Myeloproliferative neoplasms (MPN) are conditions of great interest because of the identification of their molecular basis and of the entering of new small molecules into clinical practice. The aim of this review is to report the role of mutations in the diagnosis, prognosis, and in the prediction of response to JAK inhibitors in MPN.

RECENT FINDINGS

New mutations of the CALR gene have been discovered in patients without JAK2 or MPL mutations and are now included in the World Health Organization classification system. The role of ASXL1 and SRSF2 together with the driver mutations is emerging in the prognostication of myelofibrosis.

SUMMARY

A wide mutational analysis of MPN helps to define diagnosis and prognosis. In the future, clinical trials based on a robust valuation of mutations will guide treatment decision-making towards precision medicine.

CALR gene mutational profile in myeloproliferative neoplasms with non-mutated JAK2 in Moroccan patients: A case series and germline in-frame deletion

BACKGROUND

The discovery of somatic mutations within the gene encoding calreticulin (CALR) in 2013 represented a major milestone in the molecular diagnosis of BCR-ABL negative myeloproliferative neoplasms (MPN). In fact, exome sequencing revealed that most patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF) lacking JAK2 or MPL mutations, harbor somatic insertion and/or deletion in exon 9 of CALR gene. In this study, we identified the first CALR gene mutational landscape in Moroccan patients with MPN nonmutated for the JAK2 gene.

METHODS

We performed Sanger sequencing of exon 9 of CALR gene in blood samples obtained from 33 Moroccan patients with ET or PMF non-mutated for JAK2.

RESULTS

Of the 33 patients analyzed, we detected eight distinct variants in 15 patients (45.4%); six indel mutations, five with type 1 recurrent 52bp deletion, four with type 2 recurrent 5bp insertion and one in frame deletion which was found to be a germline variant suggesting a very rare condition in MPN.

CONCLUSION

This is the first cohort reported in CALR gene mutation analysis in Morocco. Our results were concordant with studies reported up to date and very encouraging in promoting the molecular diagnosis of myeloproliferative neoplasms in Moroccan patients. Moreover, the presence of a germline in frame deletion in a symptomatic patient should undermine the effectiveness of sizing assays without DNA sequencing in the diagnosis of CALR mutations.

Differential Dynamics of CALR Mutant Allele Burden in Myeloproliferative Neoplasms during Interferon Alfa Treatment

Discovery of somatic mutations in the calreticulin gene (CALR) has identified a subgroup of Philadelphia-negative chronic myeloproliferative neoplasms (MPN) with separate haematological characteristics and prognosis. CALR mutations serve as novel markers both of diagnostic value and as targets for monitoring molecular responses during therapy. Interferon-α (IFN) selectively targets the malignant clone in a subset of MPN patients and can induce both haematological and molecular remissions in CALR mutated essential thrombocythemia (ET) patients. We investigated the response to IFN in a cohort of 21 CALR mutated MPN patients including ET, prefibrotic primary myelofibrosis (pre-PMF), and primary myelofibrosis (PMF) with a median follow-up of 31 months. For evaluation of a molecular response, we developed highly sensitive quantitative PCR (qPCR) assays for monitoring the mutant allele burden of the two most prevalent CALR mutations (type 1 and type 2). Thirteen patients (62%) experienced a decrease in the mutant allele burden with a median decline of 29% from baseline. However, only four patients, including patients with ET, pre-PMF, and PMF diagnosis, achieved molecular responder (MR) status with >50% reduction in mutant allele burden according to European LeukemiaNet (ELN) guidelines. MR patients displayed significant differences in the dynamics of the CALR mutant load with regard to time to response and dynamics in mutant allele burden after discontinuation of IFN treatment. Furthermore, we highlight the prognostic value of the CALR mutant allele burden by showing a close association with leucocyte- and platelet counts, hemoglobin concentration, in addition to plasma lactate dehydrogenase (LDH) irrespective of molecular response and treatment status.

Oncogenic Drivers in Myeloproliferative Neoplasms: From JAK2 to Calreticulin Mutations

During the past 10 years, major progress has been accomplished with the discovery of activating mutations that are associated with the vast majority of BCR-ABL negative human myeloproliferative neoplasms (MPNs). The identification in 2005 of JAK2 V617F triggered great interest in the JAK2-STAT5/STAT3 pathway. Discovery in 2006 of mutants of thrombopoietin receptor (TPO-R/MPL) and later on of mutants in negative regulators of JAK-STAT pathway led to the notion that persistent JAK2 activation is a hallmark of MPNs. In 2013, mutations in the gene coding for the chaperone calreticulin were reported in 20-30% of essential thrombocythemia and primary myelofibrosis patients. Here, we will address the question: what do we know about calreticulin that could help us understand its role in MPNs? In addition to oncogenic driver mutations, certain MPNs also exhibit epigenetic mutations. Targeting of both oncogenic drivers and epigenetic defects could be required for effective therapy.

Contemporary insights into the pathogenesis and treatment of chronic myeloproliferative neoplasms

This review is based on the deliberations at the 5th John Goldman Colloquium held in Estoril on 2nd October 2015 and the 9th post-ASH International Workshop on chronic myeloid leukemia (CML) and BCR-ABL1-negative myeloproliferative neoplasms (MPN) which took place on the 10th-11th December 2014, immediately following the 56th American Society of Hematology Annual Meeting. It has been updated since and summarizes the most recent advances in the biology and therapy of these diseases, in particular updates of genetics of MPN, novel insights from mouse MPN models, targeting CML stem cells and its niche; clinical advances include updates on JAK2 inhibitors and other therapeutic approaches to BCR-ABL1-negative MPNs, the use of alpha interferons, updates on tyrosine kinase inhibitors (TKI) randomized trials in CML, TKI cessation studies, and optimal monitoring strategies.

Optimal therapy for polycythemia vera and essential thrombocythemia: Preferred use of interferon therapy based on phase 2 trials

OBJECTIVES

To determine the value of recombinant interferon-alfa (rIFNα) in the treatment of polycythemia vera (PV) and essential thrombocythemia (ET) based on its biological activities and phase 2 clinical studies, pending completion of phase 3 trials; to determine importance of the Internet in patient decision-making in treatment selection.

RESULTS

The value of rIFNα in PV and ET is based upon its biological effects on PV stem cells and megakaryocyte proliferation. Single-arm trials are useful for life-threatening diseases when there are relatively few patients to evaluate endpoints, such as rIFNα treatment of PV and ET. Proper diagnostic criteria are mandatory; for PV, the current World Health Organization criteria emphasizing increased hemoglobin values exclude approximately one-third of eligible patients. Importance of these data: Single-arm studies in diseases exemplified by rIFNα in PV require updated diagnostic criteria for research and for clinical practice. The influence of the Internet on patient decisions for treatment is noteworthy.

CONCLUSION

The biologic basis for selecting therapy is exemplified by rIFNα in treating PV and ET. Current single-arm studies of rIFNα in PV and ET are relevant and acceptable. The importance of the Internet in patient decision-making is important.

Myeloproliferative neoplasms: A decade of discoveries and treatment advances

Myeloproliferative neoplasms (MPN) are clonal stem cell diseases, first conceptualized in 1951 by William Dameshek, and historically included chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). In 1960, Nowell and Hungerford discovered an invariable association between the Philadelphia chromosome (subsequently shown to harbor the causal BCR-ABL1 mutation) and CML; accordingly, the term MPN is primarily reserved for PV, ET, and PMF, although it includes other related clinicopathologic entities, according to the World Health Organization (WHO) classification system. In 2005, William Vainchenker and others described a Janus kinase 2 mutation (JAK2V617F) in MPN and this was followed by a series of additional descriptions of mutations that directly or indirectly activate JAK-STAT: JAK2 exon 12, myeloproliferative leukemia virus oncogene (MPL) and calreticulin (CALR) mutations. The discovery of these, mostly mutually exclusive, "driver" mutations has contributed to revisions of the WHO diagnostic criteria and risk stratification in MPN. Mutations other than JAK2, CALR and MPL have also been described in MPN and shown to provide additional prognostic information. From the standpoint of treatment, over the last 50 years, Louis Wasserman from the Unites States and Tiziano Barbui from Italy had skillfully organized and led a number of important clinical trials, whose results form the basis for current treatment strategies in MPN. More recently, allogeneic stem cell transplant, as a potentially curative treatment modality, and JAK inhibitors, as palliative drugs, have been added to the overall therapeutic armamentarium in myelofibrosis. In the current review, I will summarize the important advances made in the last 10 years regarding the science and practice of MPN.

Clinical and molecular response to interferon-α therapy in essential thrombocythemia patients with CALR mutations

Pegylated IFNα induces hematologic and molecular remission in CALR-mutated ET patients. The analysis of additional mutations highlights the presence of subclones with variable evolutions during IFNα therapy.

Calreticulin Mutations in Myeloproliferative Neoplasms: Comparison of Three Diagnostic Methods

Calreticulin (CALR) mutations have recently been reported in 70–84% of JAK2V617F-negative myeloproliferative neoplasms (MPN), and this detection has become necessary to improve the diagnosis of MPN. In a large single-centre cohort of 298 patients suffering from Essential Thrombocythemia (ET), the JAK2V617F, CALR and MPL mutations were noted in 179 (60%), 56 (18.5%) and 13 (4.5%) respectively. For the detection of the CALR mutations, three methods were compared in parallel: high-resolution melting-curve analysis (HRM), product-sizing analysis and Sanger sequencing. The sensitivity for the HRM, product-sizing analysis and Sanger sequencing was 96.4%, 98.2% and 89.3% respectively, whereas the specificity was 96.3%, 100% and 100%. In our cohort, the product-sizing analysis was the most sensitive method and was the easiest to interpret, while the HRM was sometimes difficult to interpret. In contrast, when large series of samples were tested, HRM provided results more quickly than did the other methods, which required more time. Finally, the sequencing method, which is the reference method, had the lowest sensitivity but can be used to describe the type of mutation precisely. Altogether, our results suggest that in routine laboratory practice, product-sizing analysis is globally similar to HRM for the detection of CALR mutations, and that both may be used as first-line screening tests. If the results are positive, Sanger sequencing can be used to confirm the mutation and to determine its type. Product-sizing analysis provides sensitive and specific results, moreover, with the quantitative measurement of CALR, which might be useful to monitor specific treatments.

The Role of Reactive Oxygen Species in Myelofibrosis and Related Neoplasms

Reactive oxygen species (ROS) have been implicated in a wide variety of disorders ranging between traumatic, infectious, inflammatory, and malignant diseases. ROS are involved in inflammation-induced oxidative damage to cellular components including regulatory proteins and DNA. Furthermore, ROS have a major role in carcinogenesis and disease progression in the myeloproliferative neoplasms (MPNs), where the malignant clone itself produces excess of ROS thereby creating a vicious self-perpetuating circle in which ROS activate proinflammatory pathways (NF-κB) which in turn create more ROS. Targeting ROS may be a therapeutic option, which could possibly prevent genomic instability and ultimately myelofibrotic and leukemic transformation. In regard to the potent efficacy of the ROS-scavenger N-acetyl-cysteine (NAC) in decreasing ROS levels, it is intriguing to consider if NAC treatment might benefit patients with MPN. The encouraging results from studies in cystic fibrosis, systemic lupus erythematosus, and chronic obstructive pulmonary disease warrant such studies. In addition, the antioxidative potential of the widely used agents, interferon-alpha2, statins, and JAK inhibitors, should be investigated as well. A combinatorial approach using old agents with anticancer properties together with novel JAK1/2 inhibitors may open a new era for patients with MPNs, the outlook not only being “minimal residual disease” and potential cure but also a marked improvement in inflammation-mediated comorbidities.

Management of side effects of BCR/ABL-negative chronic myeloproliferative neoplasm therapies. Focus on anagrelide

Although hydroxyurea is considered the first-line cytoreductive therapy in high-risk patients with polycythemia vera or essential thrombocythemia, approximately 20-25% of patients develop resistance or intolerance and they need an alternative therapy. Anagrelide is the treatment of choice in patients with essential thrombocythemia intolerant or with resistance to hydroxyurea. Anagrelide is usually well tolerated. Although there is concern about the increased risk of cardiac side effects, in most cases these are mild, and easily manageable. In this paper, the available evidence about the management of patients with myeloproliferative neoplasms, with a special focus on the side effects of drug therapies is reviewed.