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

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.

Extreme Levels of Platelet Count in Essential Thrombocythemia: Management and Outcome, Report of Two Cases

Myeloproliferative neoplasms including essential thrombocythemia (ET) is usually caused by somatic mutations in multiple genes, including the JAK2 (most frequently), CALR gene, and MPL. In rare cases, the disease is caused by other mutations such as THPO or TET2 gene; however, around 10–15% with ET might have triple-negative mutations. Here we present 2 cases of ET who were asymptomatic on diagnoses, but found to have extremely high platelet counts as never reported earlier. The management and treatment plan can be a challenging step. The objective is to draw attention to the early introduction of thrombocytapheresis in the management of such patients given its notable outcomes.

Recommendations for the use of pegylated interferon-α in the treatment of classical myeloproliferative neoplasms

The classical myeloproliferative neoplasms (MPN) are uncommon clonal haemopoietic malignancies characterised by excessive production of mature blood cells. Clinically, they are associated with thrombosis, haemorrhage, varying degrees of constitutional disturbance and a risk of progression to myelofibrosis or acute myeloid leukaemia. Many of the disease manifestations may be ameliorated by treatment with interferon-α (IFN), but its use in Australian MPN patients has been limited due to the inconvenience of frequent injections and side-effects. The pegylated form of IFN is a long-acting preparation, which is better tolerated, and its Pharmaceutical Benefits Scheme listing is likely to lead to increased usage. We review the literature on risks and benefits of IFN treatment for MPN, suggest criteria for patient selection in each of these diseases and discuss strategies to manage the side-effects of pegylated IFN.

Mutant calreticulin in myeloproliferative neoplasms

Recurrent mutations in calreticulin are present in ∼20% of patients with myeloproliferative neoplasms (MPNs). Since its discovery in 2013, we now have a more precise understanding of how mutant CALR, an endoplasmic reticulum chaperone protein, activates the JAK/STAT signaling pathway via a pathogenic binding interaction with the thrombopoietin receptor MPL to induce MPNs. In this Spotlight article, we review the current understanding of the biology underpinning mutant CALR-driven MPNs, discuss clinical implications, and highlight future therapeutic approaches.

Data-driven analysis of JAK2V617F kinetics during interferon-alpha2 treatment of patients with polycythemia vera and related neoplasms

Treatment with PEGylated interferon-alpha2 (IFN) of patients with essential thrombocythemia and polycythemia vera induces major molecular remissions with a reduction in the JAK2V617F allele burden to undetectable levels in a subset of patients. A favorable response to IFN has been argued to depend upon the tumor burden, implying that institution of treatment with IFN should be as early as possible after the diagnosis. However, evidence for this statement is not available. We present a thorough analysis of unique serial JAK2V617F measurements in 66 IFN-treated patients and in 6 untreated patients. Without IFN treatment, the JAK2V617F allele burden increased exponentially with a period of doubling of 1.4 year. During monotherapy with IFN, the JAK2V617F allele burden decreased mono- or bi-exponentially for 33 responders of which 28 patients satisfied both descriptions. Bi-exponential description improved the fits in 19 cases being associated with late JAK2V617F responses. The decay of the JAK2V617F allele burden during IFN treatment was estimated to have half-lives of 1.6 year for the monoexponential response and 1.0 year in the long term for the bi-exponential response. In conclusion, through data-driven analysis of the JAK2V617F allele burden, we provide novel information regarding the JAK2V617F kinetics during IFN-treatment, arguing for early intervention.

Outcome of Pregnancy in the Era of Pegylated Interferon Alpha 2a in Females with Essential Thrombocythemia: An Experience from Qatar

Myeloproliferative neoplasms are a diversified group of diseases of the hematopoietic stem cell, such as essential thrombocythemia (ET) and polycythemia vera. They are mainly caused by mutations in the following genes: JAK2, CALR, and MPL. All carry an increased risk to transform into acute leukemia or chronic myelogenous leukemia along with thrombosis and hemorrhagic complications. Treatment of such disorders during pregnancy is a challenging footstep, given the high risk of complications for both the mother and the fetus. Here, we report about two pregnant females with ET that has been treated with pegylated interferon alpha with safe and effective outcome.

Progress in elucidation of molecular pathophysiology of myeloproliferative neoplasms and its application to therapeutic decisions

Myeloproliferative neoplasms (MPNs) are hematological diseases that are driven by somatic mutations in hematopoietic stem and progenitor cells. These mutations include JAK2, CALR and MPL mutations as the main disease drivers, mutations driving clonal expansion, and mutations that contribute to progression of chronic MPNs to myelodysplasia and acute leukemia. JAK-STAT pathway has played a central role in the disease pathogenesis of MPNs. Mutant JAK2, CALR or MPL constitutively activates JAK-STAT pathway independent of the cytokine regulation. Symptomatic management is the primary goal of MPN therapy in ET and low-risk PV patients. JAK2 inhibitors and interferon-α are the established therapies in MF and high-risk PV patients.

Updates in the management of polycythemia vera and essential thrombocythemia

Polycythemia vera (PV) and essential thrombocythemia (ET) are both classic, relatively indolent, chronic Philadelphia-chromosome-negative (Ph-) myeloproliferative neoplasms (MPNs) characterized by elevated blood counts, thrombotic as well as hemorrhagic tendencies, a variety of symptoms, cumulative risks of progression to myelofibrosis and transformation to acute myeloid leukemia over time, and long survival. Molecularly, PV is more homogenous, being driven by JAK2 mutations in virtually all cases, while ET can be JAK2-, CALR-, or MPL-mutated, as well as 'triple negative'. Recent targeted next-generation sequencing efforts have identified other, nondriver gene mutations, some with prognostic relevance. Prevention of thrombotic and hemorrhagic complications continues to be the major focus of management, although symptoms are increasingly being recognized as a relatively unmet need, particularly in ET. Thrombotic risk stratification in PV is still based on age and history of thrombosis, while in ET, the additional contribution of JAK2 V617F to thrombotic risk is now well established. The associations of leukocytosis with clotting risk (in both conditions) and mortality (in PV) have drawn increased attention with the availability of ruxolitinib as a second-line treatment in PV. Similarly, there is a renewed interest in interferons with the emergence of ropeginterferon alfa-2b as a potential new frontline treatment option in PV. Drug development is more difficult in ET, the most indolent of the classic Ph- MPNs, but ruxolitinib is being studied. Triggering apoptosis via the p53 pathway through pharmacologic inhibition of human double minute 2 (and synergism with interferon) is a new, promising therapeutic strategy.

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.

Emerging drugs for essential thrombocythemia

Introduction: Despite our recent progress in the understanding of essential thrombocythemia (ET) pathogenesis, the therapeutic management of this disease has remained largely unchanged in the past decades. Treatment has mostly focused on decreasing the risk of complications, especially prevention of thrombotic or hemorrhagic events. Areas covered: Over recent years, the treatment options of ET have been expanding with some novel agents on the horizon. The classes of agents described in this review include targeted and immunomodulatory agents, such as JAK1/2 inhibitors, interferon-α, histone deacetylase inhibitors, telomerase inhibitors and human double minute 2 inhibitors. These compounds entered various stages of development, albeit the only portion of them is currently actively undergoing evaluation in clinical trials. In this review, we look at the current therapies and discuss novel agents available in the management of ET. Expert opinion: The drug development in ET possesses several challenges stemming from its relatively benign and prolonged disease course. Therapy focused on reducing the risk of thrombotic and hemorrhagic complications and symptom management needs to be chosen wisely as a vast majority of these patients have a near-normal life expectancy. To date, no therapy has shown effective and definitive alteration of the disease behavior. Although novel agents are in development and hopefully some of them will extend treatment armamentarium of ET, their exact role remains to be determined.

Next-Generation Sequencing in Myeloproliferative Neoplasms: Is This Indicated in All Patients?

PURPOSE OF REVIEW

To discuss the impact that next-generation sequencing has had on myeloproliferative neoplasm prognosis and treatment response.

RECENT FINDINGS

Extended genetic testing has led to a more comprehensive understanding of the mutational landscape in the myeloproliferative neoplasms. More refined prognostic models that predict disease course have therefore been developed. In myelofibrosis, this has led to a more nuanced prognostic assessment which is a necessary tool for the identification of potential transplant patients. The extended molecular profile may also help set expectations for ruxolitinib response duration. In essential thrombocythemia and polycythemia vera, elucidation of the molecular landscape beyond driving mutations may identify patients at risk for more rapid progression. However, results from testing are less likely to lead to action, at least in the current era. Use of next-generation sequencing has become routine in myelofibrosis, as a means of identifying patients at highest risk for progression, who may be eligible for transplantation. Extended genetic sequencing is still investigational in essential thrombocytosis and polycythemia vera, and not recommended by guidelines.

Interferon Alpha Has a Strong Anti-tumor Effect in Philadelphia-negative Myeloproliferative Neoplasms

BACKGROUND

Despite the important progress in the research of myeloproliferative neoplasms (MPN), treatment options are still limited. Currently, a cytoreductive approach is the backbone treatment, with hydroxyurea (HU) being the most important agent. However, this drug is not always well-tolerated and has been questionably linked to a potential leukemogenic effect. A valid alternative is interferon alfa (IFN-α), but it is reserved for selected patients owing to the more frequent side effects and the lack of final results from the studies directly comparing IFN-α with HU, which is why we provided the results of the so far largest real-life analysis.

PATIENTS AND METHODS

From 2000 to 2016, 63 patients with Philadelphia-negative MPN prospectively received either HU or IFN-α.

RESULTS

During a median follow-up period of 121 months (range, 88-168 months), 97% of the patients treated with IFN-α achieved a hematologic response (60% complete, 37% partial) compared with 78% in the HU group (56% complete, 20% partial; P < .01). Molecular responses were limited to patients treated with IFN-α. IFN-α was well-tolerated with no secondary malignancy, whereas HU was associated with more toxic events and cases of leukemic transformation. A significantly longer progression-free survival (5.0 vs. 3.1 years; P < .001) and overall survival (7.8 vs. 5.8 years; P = .006) were observed in the IFN-α group compared with the HU cohort.

CONCLUSION

Our data support IFN-α as a more valid therapeutic option owing to its more profound hematologic responses, durable molecular remissions, long-term disease control, and reduced risk of leukemic transformation with a favorable toxicity profile.

Genomics and Precision Medicine: Molecular Diagnostics Innovations Shaping the Future of Healthcare in Qatar

Unprecedented developments in genomics research and ancillary technologies are creating the potential for astonishing changes in both the healthcare field and the life sciences sector. The innovative genomics applications include the following: (1) embracing next generation sequencing (NGS) in clinical diagnostics setting (applying both whole genome and exome sequencing), (2) single cell sequencing studies, (3) quantifying gene expression changes (including whole transcriptome sequencing), (4) pharmacogenomics, and (5) cell-free DNA blood-based testing. This minireview describes the impact of clinical genomics disruptive innovations on the healthcare system in order to provide better diagnosis and treatment. The observed evolution is not limited to the point-of-care services. Genomics technological breakthroughs are pushing the healthcare environment towards personalized healthcare with the real potential to attain better wellbeing. In this article, we will briefly discuss the Gulf region population-based genome initiatives that intend to improve personalized healthcare by offering better prevention, diagnosis, and therapy for the individual (precision medicine). Qatar’s endeavor in genomics medicine will be underscored including the private Applied Biomedicine Initiative (ABI).

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.

Perspectives on interferon-alpha in the treatment of polycythemia vera and related myeloproliferative neoplasms: minimal residual disease and cure?

The first clinical trials of the safety and efficacy of interferon-alpha2 (IFN-alpha2) were performed about 30 years ago. Since then, several single-arm studies have convincingly demonstrated that IFN-alpha2 is a highly potent anti-cancer agent in several cancer types but unfortunately not being explored sufficiently due to a high toxicity profile when using non-pegylated IFN-alpha2 or high dosages or due to competitive drugs, that for clinicians at first glance might look more attractive. Within the hematological malignancies, IFN-alpha2 has only recently been revived in patients with the Philadelphia-negative myeloproliferative neoplasms-essential thrombocytosis, polycythemia vera, and myelofibrosis (MPNs)-and in patients with chronic myelogenous leukemia (CML) in combination with tyrosine kinase inhibitors. In this review, we tell the IFN story in MPNs from the very beginning in the 1980s up to 2018 and describe the perspectives for IFN-alpha2 treatment of MPNs in the future. The mechanisms of actions are discussed and the impact of chronic inflammation as the driving force for clonal expansion and disease progression in MPNs is discussed in the context of combination therapies with potent anti-inflammatory agents, such as the JAK1-2 inhibitors (licensed only ruxolitinib) and statins as well. Interferon-alpha2 being the cornerstone treatment in MPNs and having the potential of inducing minimal residual disease (MRD) with normalization of the bone marrow and low-JAK2V617F allele burden, we believe that combination therapy with ruxolitinib may be even more efficacious and hopefully revert disease progression in many more patients to enter the path towards MRD. In patients with advanced and transforming disease towards leukemic transformation or having transformed to acute myeloid leukemia, "triple therapy" is proposed as a novel treatment modality to be tested in clinical trials combining IFN-alpha2, DNA-hypomethylator, and ruxolitinib. The rationale for this "triple therapy" is given, including the fact that even in AML, IFN-alpha2 as monotherapy may revert disease progression. We envisage a new and bright future with many more patients with MPNs obtaining MRD on the above therapies. From this stage-and even before-vaccination strategies may open a new horizon with cure being the goal for some patients.

Clinical Exome Sequencing unravels new disease-causing mutations in the myeloproliferative neoplasms: A pilot study in patients from the state of Qatar

Clinical Exome Sequencing (CES) has increasingly become a popular diagnostic tool in patients suffering from genetic disorders that are clinically and genetically complicated. Myeloproliferative Neoplasms (MPNs) is an example of a heterogeneous disorder. In Qatar, familial cases of MPNs are more frequently seen than described in the literature. In this study, we aimed to use CES to classify six Qatari subjects that were suspected of clinical diagnosis of MPNs, according to the WHO 2008 diagnostic criteria for hematologic malignancies, and identify variants that can potentially explain the phenotypic diversity of MPNs. We sequenced six Qatari subjects using CES, of whom, three probands were unrelated families and three members were from the same family, all probands come from consanguineous families, and had a positive family history of MPNs. CES identified 61 variants in 50 genes; of which, 13 were recurrently mutated in our patients. Ten novel variants were identified in ten known genes related to MPNs and seven variants were identified in seven novel candidate genes. The genotype of the six subjects was due to a combination of different variants in different genes. This study serves as a pilot study to investigate the complexity of the genotype of patients with MPNS in Qatar, and serves as a guide for further well-controlled genetic epidemiological studies for patients with MPNs. CES is a powerful tool to be used in the genetic clinics for differential and definitive diagnosis of patients with MPNs.

JAK2 (and other genes) be nimble with MPN diagnosis, prognosis, and therapy

Now that the spectrum of somatic mutations that initiate, propagate, and drive the progression of myeloproliferative neoplasms (MPNs) has largely been defined, recent efforts have focused on integrating this information into clinical decision making. In this regard, the greatest progress has been made in myelofibrosis, in which high-molecular-risk mutations have been identified and incorporated into prognostic models to help guide treatment decisions. In this chapter, we focus on advances in 4 main areas: (1) What are the MPN phenotypic driver mutations? (2) What constitutes high molecular risk in MPN (focusing on ASXL1)? (3) How do we risk-stratify patients with MPN? And (4) What is the significance of molecular genetics for MPN treatment? Although substantial progress has been made, we still have an incomplete understanding of the molecular basis for phenotypic diversity in MPN, and few rationally designed therapeutic approaches to target high-risk mutations are available. Ongoing research efforts in these areas are critical to understanding the biological consequences of genetic heterogeneity in MPN and to improving outcomes for patients.

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.

Heterogeneity in myeloproliferative neoplasms: Causes and consequences

Myeloproliferative neoplasms (MPNs) are haematopoietic stem cell-derived clonal disorders characterised by proliferation of some or all myeloid lineages, depending on the subtype. MPNs are classically categorized into three disease subgroups; essential thrombocythaemia (ET), polycythaemia vera (PV) and primary myelofibrosis (PMF). The majority (>85%) of patients carry a disease-initiating or driver mutation, the most prevalent occurring in the janus kinase 2 gene (JAK2 V617F), followed by calreticulin (CALR) and myeloproliferative leukaemia virus (MPL) genes. Although these diseases are characterised by shared clinical, pathological and molecular features, one of the most challenging aspects of these disorders is the diverse clinical features which occur in each disease type, with marked variability in risks of disease complications and progression to leukaemia. A remarkable aspect of MPN biology is that the JAK2 V617F mutation, often occurring in the absence of additional mutations, generates a spectrum of phenotypes from asymptomatic ET through to aggressive MF, associated with a poor outcome. The mechanisms promoting MPN heterogeneity remain incompletely understood, but contributing factors are broad and include patient characteristics (gender, age, comorbidities and environmental exposures), additional somatic mutations, target disease-initiating cell, bone marrow microenvironment and germline genetic associations. In this review, we will address these in detail and discuss their role in heterogeneity of MPN disease phenotypes. Tailoring patient management according to the multiple different factors that influence disease phenotype may prove to be the most effective approach to modify the natural history of the disease and ultimately improve outcomes for patients.

Ropeginterferon alpha-2b targets JAK2V617F-positive polycythemia vera cells in vitro and in vivo

Polycythemia vera is characterized by the acquisition of the JAK2V617F mutation. Recommended treatments include hydroxyurea and interferon-alpha. Several groups have reported a reduction in the JAK2 mutant allele burden in interferon-treated patients, but significance of this observation is questioned. We characterized the activity of ropeginterferon alpha-2b, a novel form of interferon-alpha recently shown to be safe and efficacious in polycythemia vera. Ropeginterferon was able to inhibit the proliferation of the HEL, UKE-1, and UT-7 JAK2-mutant cell lines while sparing JAK2-wild-type UT-7 and normal CD34+ cells growth. In vitro treatment of erythroid progenitors derived from PV patients showed that ropeginterferon could considerably inhibit the growth of endogenous erythroid colonies, a hallmark of polycythemia vera. Finally, we could study in sequential samples the clonal architecture of erythroid progenitors derived from patients included in a randomized study comparing hydroxyurea to ropeginterferon. After 1 year of treatment with ropeginterferon, the ratio of JAK2-mutated to wild-type colonies grown from bone marrow progenitors was reduced by 64%, compared to 25% in patients receiving hydroxyurea. This study shows that ropeginterferon has a potent targeted activity against JAK2-mutant cells and is able to drastically reduce the proportion of malignant progenitors in patients treated with this drug.

Novel Strategies for Peptide-Based Vaccines in Hematological Malignancies

Peptides vaccination is an interesting approach to activate T-cells toward desired antigens in hematological malignancies. In addition to classical tumor associated antigens, such as cancer testis antigens, new potential targets for peptide vaccination comprise neo-antigens including JAK2 and CALR mutations, and antigens from immune regulatory proteins in the tumor microenvironment such as programmed death 1 ligands (PD-L1 and PD-L2). Immunosuppressive defenses of tumors are an important challenge to overcome and the T cell suppressive ligands PD-L1 and PD-L2 are often present in tumor microenvironments. Thus, PD-L1 and PD-L2 are interesting targets for peptide vaccines in diseases where the tumor microenvironment is known to play an essential role such as multiple myeloma and follicular lymphoma. In myelodysplastic syndromes the drug azacitidine re-exposes tumor associated antigens, why vaccination with related peptides would be an interesting addition. In myeloproliferative neoplasms the JAK2 and CALR mutations has proven to be immunogenic neo-antigens and thus possible targets for peptide vaccination. In this mini review we summarize the basis for these novel approaches, which has led to the initiation of clinical trials with various peptide vaccines in myelodysplastic syndromes, myeloproliferative neoplasms, multiple myeloma, and follicular lymphoma.

A triplex probe-based TaqMan qPCR assay for Calreticulin type I and II mutation detection

BACKGROUND

Calreticulin (CALR) exon 9 frameshift mutations have recently been identified in 30-40% of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF) without JAK2 or MPL mutations. We aimed to develop a qPCR assay to screen type I and II mutations of CALR.

METHODS

Three different fluorescent-labeled hydrolysis probes and one pair of primers in a closed-tube system were developed to detect CALR type I and II mutations and distinguish them from wild-type. The sensitivity and specificity were validated using TA-cloning plasmids containing CALR wild-type and type I and II mutants, respectively. Fifty-nine ET and PMF specimens were screened by TaqMan qPCR and sequenced by Sanger sequencing. For intra-assay validation, 20 replicates of the assay were performed with each sample. For inter-assay validation, four replications of each sample were carried out and repeated continuously for 5 days.

RESULTS

We found that triplex probe-based TaqMan qPCR was reliable in detecting CALR type I and II mutants within DNA that was diluted to 1% of total DNA with the wild-type DNA as background. In 59 patient specimens, six of the observed mutations of CALR were type I and five were type II. Genotyping results obtained from TaqMan qPCR were 100% concordant with Sanger sequencing. The intra- and inter-assay CVs of TaqMan qPCR were less than 3%, respectively.

CONCLUSIONS

Triplex probe-based TaqMan qPCR is an accurate and sensitive method for screening ET or PMF patients with type I and II mutations in CALR.

Calreticulin mutation analysis in non-mutated Janus kinase 2 essential thrombocythemia patients in Chiang Mai University: analysis of three methods and clinical correlations

OBJECTIVES

The primary objective was to determine the prevalence of calreticulin (CALR) mutation in patients with non-JAK2V617F mutated essential thrombocythemia (ET). The secondary objectives were to evaluate the accuracy of CALR mutation analysis by high-resolution melting (HRM) analysis and real-time polymerase chain reaction (PCR) compared with DNA sequencing and to compare clinical characteristics of CALR mutated and JAK2V617F mutated ET.

METHODS

This was a prospective cohort study involving ET patients registered at Chiang Mai University in the period September 2015-September 2017 who were aged more than 2 years, and did not harbor JAK2V617F mutation. The presence of CALR mutation was established by DNA sequencing, HRM, and real-time PCR for type 1 and type 2 mutation. Clinical data were compared with that from ET patients with mutated JAK2V617F.

RESULTS

Twenty-eight patients were enrolled onto the study. CALR mutations were found in 10 patients (35.7%). Three patients had type 1 mutation, 5 patients had type 2 mutation, 1 patient had type 18 mutation, and 1 patients had novel mutations (c.1093 C-G, c.1098_1131 del, c.1135 G-A). HRM could differentiate between the types of mutation in complete agreement with DNA sequencing. Patients with a CALR mutation showed a significantly greater male predominance and had a higher platelet count when compared with 42 JAK2V617F patients.

DISCUSSION AND CONCLUSIONS

The prevalence of CALR mutation in JAK2V617F-negative ET in this study is 35.7%. HRM is an effective method of detecting CALR mutation and is a more advantageous method of screening for CALR mutation.

Contemporary Use of Interferon Therapy in the Myeloproliferative Neoplasms

PURPOSE OF REVIEW

The purpose of this article is to review the current evidence behind interferon therapy in patients with myeloproliferative neoplasms.

RECENT FINDINGS

Preliminary analysis suggests that interferon may be non-inferior to hydroxyurea in patients with polycythemia vera and essential thrombocytosis. Responses have been observed regardless of JAK2 mutational status, but the presence of non-JAK2 somatic mutations may negatively influence response rates. Pegylated interferon has proven efficacy for patients with myeloproliferative neoplasms. Both newly diagnosed and previously treated patients with polycythemia vera and essential thrombocytosis exhibit high hematologic response rates, and some of these patients achieve molecular responses as well. Interferon therapy leads to lower rates of hematologic response in MF patients, but patients earlier on in their disease course have a better chance of responding. There are ongoing trials comparing pegylated interferon to hydroxyurea in essential thrombocytosis (ET) and polycythemia vera (PV), and early analysis suggests non-inferiority. However, longer follow-up is needed before drawing any conclusions. Future research is needed to better define characteristics of the best responders and to determine whether novel forms of interferon therapy or combination therapy with interferon can enhance efficacy and tolerability.

Essential thrombocythemia treatment algorithm 2018

Current drug therapy for myeloproliferative neoplasms, including essential thrombocythemia (ET) and polycythemia vera (PV), is neither curative nor has it been shown to prolong survival. Fortunately, prognosis in ET and PV is relatively good, with median survivals in younger patients estimated at 33 and 24 years, respectively. Therefore, when it comes to treatment in ET or PV, less is more and one should avoid exposing patients to new drugs that have not been shown to be disease-modifying, and whose long-term consequences are suspect (e.g., ruxolitinib). Furthermore, the main indication for treatment in ET and PV is to prevent thrombosis and, in that regard, none of the newer drugs have been shown to be superior to the time-tested older drugs (e.g., hydroxyurea). We currently consider three major risk factors for thrombosis (history of thrombosis, JAK2/MPL mutations, and advanced age), in order to group ET patients into four risk categories: "very low risk" (absence of all three risk factors); "low risk" (presence of JAK2/MPL mutations); "intermediate-risk" (presence of advanced age); and "high-risk" (presence of thrombosis history or presence of both JAK2/MPL mutations and advanced age). Herein, we provide a point-of-care treatment algorithm that is risk-adapted and based on evidence and decades of experience.

What are the current treatment approaches for patients with polycythemia vera and essential thrombocythemia?

Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative neoplasms that are characterized by thrombohemorrhagic complications, symptom burden, and impaired survival mainly due to thrombosis, progression to myelofibrosis, and transformation to acute leukemia. In this manuscript, we will review the most recent changes in diagnostic criteria, the improvements in risk stratification, and the "state of the art" in the daily management of these disorders. The role of conventional therapies and novel agents, interferon α and the JAK2 inhibitor ruxolitinib, is critically discussed based on the results of a few basic randomized clinical studies. Several unmet needs remain, above all, the lack of a curative approach that might overcome the still burdensome morbidity and mortality of these hematologic neoplasms, as well as the toxicities associated with therapeutic agents.

Benefits and pitfalls of pegylated interferon-α2a therapy in patients with myeloproliferative neoplasm-associated myelofibrosis: a French Intergroup of Myeloproliferative neoplasms (FIM) study

We have previously described the safety and efficacy of pegylated interferon-α2a therapy in a cohort of 62 patients with myeloproliferative neoplasm-associated myelofibrosis followed in centers affiliated to the French Intergroup of Myeloproliferative neoplasms. In this study, we report their long-term outcomes and correlations with mutational patterns of driver and non-driver mutations analyzed by targeted next generation sequencing. The median age at diagnosis was 66 years old, the median follow-up since starting pegylated interferon was 58 months. At the time of analysis, 30 (48.4%) patients were alive including 16 still being treated with pegylated interferon. The median survival of patients with intermediate and high-risk prognostic Lille and dynamic International Prognostic Scoring System scores treated with pegylated interferon was increased in comparison to that of historical cohorts. In addition, overall survival was significantly correlated with the duration of pegylated interferon therapy (70 versus 30 months after 2 years of treatment, P<10⁻¹²). JAK2^V617F allele burden was decreased by more than 50% in 58.8% of patients and two patients even achieved complete molecular response. Next-generation sequencing analyses performed in 49 patients showed that 28 (57.1%) of them carried non-driver mutations. The presence of at least one additional mutation was associated with a reduction of both overall and leukemia-free survival. These findings in a large series of patients with myelofibrosis suggest that pegylated interferon therapy may provide a survival benefit for patients with intermediate- or high-risk Lille and dynamic International Prognostic Scoring System scores. It also reduced the JAK2^V617F allele burden in most patients. These results further support the use of pegylated interferon in selected patients with myelofibrosis.

Targeted sequencing reveals genetic variants associated with sensitivity of 79 human cancer xenografts to anticancer drugs

Although there has been progress moving from a 'one-size-fits-all' cytotoxic approach to personalized molecular medicine, the majority of patients with cancer receive chemotherapy using cytotoxic anticancer drugs. The sequencing analysis of 409 genes associated with cancer was conducted in the present study using 59 DNA sequences extracted from human cancer xenografts implanted into nude mice, of which sensitivity to 9 cytotoxic anticancer drugs [5-fluorouracil, nimustine, adriamycin, cyclophosphamide, cisplatin, mitomycin C (MMC), methotrexate, vincristine (VCR), and vinblastine] was examined. The present study investigated the association between the sensitivities of the xenografts to the 9 anticancer drugs and the frequency of single nucleotide variants (SNV). The correlation between the expression level of the genes and sensitivities to the 9 drugs in the above xenografts was also estimated. In the screening study using 59 xenografts, 3 SNVs (rs1805321, rs62456182 in PMS1 Homolog 2, Mismatch Repair System Component and rs13382825 in LDL Receptor Related Protein 1B), were associated with sensitivity to VCR and MMC, respectively (P<0.001). A replication study of 596 SNVs was subsequently performed, which indicated P<0.05 in the screening study using independent samples of 20 xenografts. A combined result of the screening and replication studies indicated that 35 SNVs were potentially associated with sensitivities to one or more of the nine anticancer drugs (P_combined=0.0011-0.035). Of the 35 SNVs, rs16903989 and rs201432181 in Leukemia Inhibitory Factor Receptor α and Adhesion G Protein-Coupled Receptor A2 were commonly associated with sensitivity to 2 or 4 anticancer drugs, respectively. These findings provide novel insights which may benefit the development of personalized anticancer therapy for patients with cancer in the future.

Mutations in myeloproliferative neoplasms - their significance and clinical use

INTRODUCTION

Clonal hematologic diseases of the blood such as polycythemia vera, essential thrombocythemia and primary myelofibrosis belong to the BCR-ABL negative Myeloproliferative Neoplasms (MPN). These diseases are characterized by clonal expansion of hematopoietic precursor cells followed by increased production of differentiated cells of the myeloid lineage. Initiation of clonal hematopoiesis, formation of a clinical phenotype as well as disease progression form part of MPN disease evolution. The disease is driven by acquired somatic mutations in critical pathways such as cytokine signaling, epigenetic regulation, RNA splicing, and transcription factor signaling. Areas covered: The following review aims to provide an overview of the mutational landscape of MPN, the impact of these mutations in MPN pathogenesis as well as their prognostic value. Finally, a summary of how these mutations are being used or could potentially be used for the treatment of MPN patients is presented. Expert commentary: The genetic landscape of MPN patients has been successfully dissected within the past years with the advent of new sequencing technologies. Integrating the genetic information within a clinical setting is already benefitting patients in terms of disease monitoring and prognostic information of disease progression but will be further intensified within the next years.

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.

Developmental Therapeutics in Myeloproliferative Neoplasms

The unprecedented success of the Janus kinase (JAK) 1/2 inhibitor ruxolitinib in myelofibrosis (MF) provided much-needed impetus for clinical drug development for the Philadelphia chromosome-negative myeloproliferative neoplasms. The survival benefit conferred by this agent, along with its marked efficacy with regard to spleen volume and symptom reduction, have made ruxolitinib the cornerstone of drug therapy in MF. However, there remain significant unmet needs in the treatment of patients with MF, and many novel classes of agents continue to be investigated in efforts to build on the progress made with ruxolitinib. These include inhibitors of histone deacetylases (HDACs) and DNA methyltransferases, phosphatidylinositol-3-kinase isoforms, heat shock protein 90, cyclin-dependent kinases 4/6, and Hedgehog signaling, among others. In parallel, other JAK inhibitors with potential for less myelosuppression or even improvement of anemia, greater selectivity for JAK1 or JAK2, and the ability to overcome JAK inhibitor persistence are in various stages of development. First-in-class agents such as the activin receptor IIA ligand trap sotatercept (for anemia of MF), the telomerase inhibitor imetelstat, and the antifibrotic agent PRM-151 (recombinant human pentraxin-2) are also in clinical trials. In polycythemia vera, a novel interferon administered every 2 weeks is being developed for front-line therapy in high-risk individuals, and inhibitors of human double minute 2 (HDM2) have shown promise in preclinical studies, as have HDAC inhibitors such as givinostat (both in the laboratory and in the clinic). Ruxolitinib is approved for second-line therapy of polycythemia vera and is being developed for essential thrombocythemia.

High-throughput sequencing for noninvasive disease detection in hematologic malignancies

Noninvasive monitoring of minimal residual disease (MRD) has led to significant advances in personalized management of patients with hematologic malignancies. Improved therapeutic options and prolonged survival have further increased the need for sensitive tumor assessment that can inform treatment decisions and patient outcomes. At diagnosis or relapse of most hematologic neoplasms, malignant cells are often easily accessible in the blood as circulating tumor cells (CTCs), making them ideal targets to noninvasively profile the molecular features of each patient. In other cancer types, CTCs are generally rare and noninvasive molecular detection relies on circulating tumor DNA (ctDNA) shed from tumor deposits into circulation. The ability to precisely detect and quantify CTCs and ctDNA could minimize invasive procedures and improve prediction of clinical outcomes. Technical advances in MRD detection methods in recent years have led to reduced costs and increased sensitivity, specificity, and applicability. Among currently available tests, high-throughput sequencing (HTS)-based approaches are increasingly attractive for noninvasive molecular testing. HTS-based methods can simultaneously identify multiple genetic markers with high sensitivity and specificity without individual optimization. In this review, we present an overview of techniques used for noninvasive molecular disease detection in selected myeloid and lymphoid neoplasms, with a focus on the current and future role of HTS-based assays.

Significance of combined detection of JAK2V617F, MPL and CALR gene mutations in patients with essential thrombocythemia

The aim of this study was to analyze the mutation rate of JAK2V617F, MPLW515L/K and CALR genes in adult patients with essential thrombocythemia (ET) and the accuracy of the combined detection by the receiver operating curve. Three hundred and forty-two cases with high-platelets (≥300×10⁹/l) were consecutively selected. The patients were analyzed for routine blood examination, bone marrow biopsy and genetic testing. One hundred and fifty-four cases (45.03%) were diagnosed with ET and 188 cases of secondary thrombocythemia according to the hematopoietic and lymphoid tissue tumor classification standards of 2008. It was found that the mutant type of three genes showed three bands, whereas only one band for wild-type. The JAK2V617F and MPL mutations did not cause a change in the open reading frame and the CALR mutation resulted in its change. The mutation rate of JAK2V617F and CALR in ET group was significantly higher than that in the secondary thrombocythemia group (p<0.05). The positive mutation rate of MPL was only 4.55%. JAK2V617F-positive mutation alone was used to diagnose with ET. The area under the curve (AUC) was 0.721. The sensitivity was 72.4%, the specificity was 79.5% and the cut-off value was 0.25. When CALR-positive mutation alone was used to diagnose ET, the AUC, sensitivity, specificity and cut-off value were 0.664, 68.4, 82.4 and 0.09%, respectively. JAK2V617F combined with CALR mutation were used for diagnosis of ET. The AUC was 0.862, the sensitivity was 85.9%, the specificity was 87.8%, and the cut-off values were 0.21 and 0.07. In conclusion, the positive mutation rate of JAK2V617F and CALR in ET was higher, and the sensitivity, specificity and accuracy of the diagnosis of ET were significantly improved using the detection of JAK2V617F and CALR.

Recommendations for molecular testing in classical Ph1-neg myeloproliferative disorders-A consensus project of the Italian Society of Hematology

The discovery that Philadelphia-negative classical myeloproliferative neoplasms (MPNs) present with several molecular abnormalities, including the mostly represented JAK2V617F mutation, opened new horizons in the diagnosis, prognosis, and monitoring of these disorders. However, the great strides in the knowledge on molecular genetics need parallel progresses on the best approach to methods for detecting and reporting disease-associated mutations, and to shape the most effective and rationale testing pathway in the diagnosis, prognosis and monitoring of MPNs. The MPN taskforce of the Italian Society of Hematology (SIE) assessed the scientific literature and composed a framework of the best, possibly evidence-based, recommendations for optimal molecular methods as well as insights about the applicability and interpretation of those tests in the clinical practice, and clinical decision for testing MPNs patients. The issues dealt with: source of samples and nucleic acid template, the most appropriate molecular abnormalities and related detection methods required for diagnosis, prognosis, and monitoring of MPNs, how to report a diagnostic molecular test, calibration and quality control. For each of these issues, practice recommendations were provided.

Pegylated interferon alfa-2a in patients with essential thrombocythaemia or polycythaemia vera: a post-hoc, median 83 month follow-up of an open-label, phase 2 trial

BACKGROUND

Pegylated interferon alfa-2a is an immunomodulatory agent used to treat polycythemia vera. The durability of responses and long-term safety of this drug in patients with polycythaemia vera and essential thrombocythaemia have not been reported. Here, we present long-term efficacy and safety data from a single-centre, open-label, phase 2 trial, after a median of 83 months follow up.

METHODS

Patients older than 18 years who were diagnosed with essential thrombocythaemia or polycythaemia vera according to 2001 WHO criteria were eligible to enrol in our study. The initial starting dose of pegylated interferon alfa-2a was 450 μg subcutaneously once per week, but was decreased in a stepwise manner due to toxic effects to a final starting dose of 90 mg per week: three patients were started at a dose of 450 mg per week, three at 360 mg per week, 19 at 270 mg per week, 26 at 180 mg per week, and 32 at 90 mg per week. Treatment was continued for as long as the patients derived clinical benefit with reductions in dose and frequency of administration allowed at the discretion of the treating physician. Haematological responses were assessed every 3-6 months on the basis of blood counts as defined by the European LeukemiaNet critieria. The primary endpoint of the initial study was the proportion of patients with a haematological response. Complete haematological response was defined as normalisation of blood counts (for patients with essential thrombocythaemia, platelets ≤440 × 109 per L; for patients with polycythaemia vera, haemoglobin <15·0 g/L without phlebotomy) with complete resolution of palpable splenomegaly or symptoms in the absence of a thrombotic event. Data were analysed with descriptive statistics and in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT00452023 and is ongoing but not enrolling new patients.

FINDINGS

Between May 21, 2005, and Dec 1, 2015, patients were followed up for a median of 83 months (IQR 69-94 months). Pegylated interferon alfa-2a induced haematological (66 [80%] of 83 patients) and molecular responses (35 [63%] of 55 patients) in 40 patients with essential thrombocythaemia and 43 patients with polycythaemia vera, with median durations of 66 months (IQR 35-83) and 53 months (24-70), respectively. 26 (39%) of 66 haematological responders and 25 (71%) of 35 molecular responders (with the JAK2 Val617Phe mutation) have maintained some response during follow-up: 49% maintained their best molecular response (nine of ten patients who had a complete response, five of 20 who had a partial response, and three of five who had a minor response). The incidence of major venous-thrombotic events during the study was 1·22 per 100 person-years. Overall, 18 (22%) of 83 patients discontinued therapy due to treatment-related toxicity. Although toxicity rates decreased over time, five patients had treatment-limiting grade 3 or 4 toxicities after 60 months on therapy. 32 patients are still enrolled on the study.

INTERPRETATION

Pegylated interferon alfa-2a can induce durable haematological and molecular responses in patients with essential thrombocythaemia and polycythaemia vera. This drug alone and in combination with other drugs could be explored further in clinical trials.

FUNDING

US National Cancer Institute.

Polycythemia and Thrombocytosis

Myeloproliferative neoplasms (MPNs) are diseases of excess cell proliferation from bone marrow precursors. Two classic MPNs, polycythemia vera (PV) and essential thrombocytosis (ET), are conditions of excess proliferation of red blood cells and platelets, respectively. Although PV and ET involve different cells in the myeloid lineage, their clinical presentations have shared features, consistent with overlapping mutations in growth factor signaling. The management of both diseases involves minimizing the risk of thrombotic and hemorrhagic complications. Both PV and ET can progress to myelofibrosis or acute myeloid leukemia, portending a poor prognosis. MPNs can also present as primary myelofibrosis.

Myeloproliferative neoplasm stem cells

Myeloproliferative neoplasms (MPNs) arise in the hematopoietic stem cell (HSC) compartment as a result of the acquisition of somatic mutations in a single HSC that provides a selective advantage to mutant HSC over normal HSC and promotes myeloid differentiation to engender a myeloproliferative phenotype. This population of somatically mutated HSC, which initiates and sustains MPNs, is termed MPN stem cells. In >95% of cases, mutations that drive the development of an MPN phenotype occur in a mutually exclusive manner in 1 of 3 genes: JAK2, CALR, or MPL The thrombopoietin receptor, MPL, is the key cytokine receptor in MPN development, and these mutations all activate MPL-JAK-STAT signaling in MPN stem cells. Despite common biological features, MPNs display diverse disease phenotypes as a result of both constitutional and acquired factors that influence MPN stem cells, and likely also as a result of heterogeneity in the HSC in which MPN-initiating mutations arise. As the MPN clone expands, it exerts cell-extrinsic effects on components of the bone marrow niche that can favor the survival and expansion of MPN stem cells over normal HSC, further sustaining and driving malignant hematopoiesis. Although developed as targeted therapies for MPNs, current JAK2 inhibitors do not preferentially target MPN stem cells, and as a result, rarely induce molecular remissions in MPN patients. As the understanding of the molecular mechanisms underlying the clonal dominance of MPN stem cells advances, this will help facilitate the development of therapies that preferentially target MPN stem cells over normal HSC.

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.

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.