Molecular remission and reversal of myelofibrosis in response to imatinib mesylate treatment in patients with the myeloproliferative variant of hypereosinophilic syndrome

Approach to the patient with eosinophilia in the era of tyrosine kinase inhibitors and biologicals

PURPOSE OF REVIEW

In this review, we aim to explore the optimal approach to patients presenting with eosinophilia, considering recent advances in diagnostic and therapeutic strategies. Specifically, we focus on the integration of novel therapies into clinical practice to improve patient outcomes.

RECENT FINDINGS

Advanced insights into the clinical and genetic features of eosinophilic disorders have prompted revisions in diagnostic criteria by the World Health Organization classification (WHO-HAEM5) and the International Consensus Classification (ICC). These changes reflect a growing understanding of disease pathogenesis and the development of targeted treatment options. The therapeutic landscape now encompasses a range of established and novel therapies. For reactive conditions, drugs targeting the eosinophilopoiesis, such as those aimed at interleukin-5 or its receptor, have demonstrated significant potential in decreasing blood eosinophil levels and minimizing disease flare-ups and relapse. These therapies have the potential to mitigate the side effects commonly associated with prolonged use of oral corticosteroids or immunosuppressants. Myeloid and lymphoid neoplasms with eosinophilia and tyrosine kinase (TK) gene fusions are managed by various TK inhibitors with variable efficacy. Diagnosis and treatment rely on a multidisciplinary approach. By incorporating novel treatment options into clinical practice, physicians across different disciplines involved in the management of eosinophilic disorders can offer more personalized and effective care to patients. However, challenges remain in accurately diagnosing and risk-stratifying patients, as well as in navigating the complexities of treatment selection.

Hypereosinophilia and Left Ventricular Thrombus: A Case Report and Literature Review

Left ventricular thrombus (LVT) has historically been reported as a complication of acute left ventricular (LV) myocardial infarction. It is most commonly observed in cases of LV systolic dysfunction attributed to ischemic or nonischemic etiologies. Conversely, the occurrence of LVT in normal LV systolic function is an exceptionally rare presentation and is predominantly associated with conditions such as hypereosinophilic syndrome (HES), cardiac amyloidosis, left ventricular noncompaction, hypertrophic cardiomyopathy (HCM), hypercoagulability states, immune-mediated disorders, and malignancies. Notably, hypereosinophilia (HE) has been linked with thrombotic events. Intracardiac thrombus is a well-known complication of eosinophilic myocarditis (EM) or Loeffler endomyocarditis, both of which are considered clinical manifestations of HES. We present a case of a 63-year-old male with normal LV systolic function, HE, and noncontributory hypercoagulability workup, who presented with thromboembolic complications arising from LVT. Interestingly, the diagnostic evaluation for EM and Loeffler endocarditis was nonconfirmatory. Additionally, we performed a literature review to delineate all similar cases. This article also outlines the pathophysiology, diagnosis, and treatment approaches for hypereosinophilic cardiac involvement with a specific focus on LVT.

World Health Organization and International Consensus Classification of eosinophilic disorders: 2024 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of non-hematologic (secondary or reactive) and hematologic (primary or clonal) disorders with the potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 109/L, and may be associated with tissue damage. After the exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of various tests. They include morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, molecular testing and flow immunophenotyping to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2022 World Health Organization and International Consensus Classification endorse a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions" (MLN-eo-TK), and the MPN subtype, "chronic eosinophilic leukemia" (CEL). Lymphocyte-variant HE is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g., <1.5 × 109/L) without symptoms or signs of organ involvement, a watch and wait approach with close follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Pemigatinib was recently approved for patients with relapsed or refractory FGFR1-rearranged neoplasms. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-α have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. Mepolizumab, an interleukin-5 (IL-5) antagonist monoclonal antibody, is approved by the U.S Food and Drug Administration for patients with idiopathic HES. Cytotoxic chemotherapy agents, and hematopoietic stem cell transplantation have been used for aggressive forms of HES and CEL, with outcomes reported for limited numbers of patients. Targeted therapies such as the IL-5 receptor antibody benralizumab, IL-5 monoclonal antibody depemokimab, and various tyrosine kinase inhibitors for MLN-eo-TK, are under active investigation.

Biologic therapies for hypereosinophilic disorders: From tyrosine kinase inhibitors to monoclonal antibodies. Towards an increasingly customized management?

Hypereosinophilic syndromes (HES) encompass a wide range of disorders characterized by persistent peripheral blood hypereosinophilia (HE) (i.e., an eosinophil count ≥1.5 × 10⁹/L and ≥ 10% eosinophils preferably with a minimal duration of 6 months if documentation is available) associated with organ damage and/or dysfunction attributable to tissue eosinophilic infiltrate and release of granule contents. In most cases, HE is associated with atopic conditions/allergies, parasitic infections, medications, autoimmune disorders and/or solid tumors in most cases. More rarely, it can be one of the dominant manifestations of an underlying myeloid/lymphoid neoplasm. With regard to hematological forms, in recent decades the advances in understanding the pathogenic aspects of HES have led to a growing interest in these diseases, and in the 2016 WHO classification multiple subgroups were defined according to the molecular profile with the aim of better characterizing these syndromes and establishing which patients will benefit from specific pharmacological targeted therapies. This review article will provide a comprehensive overview of possible therapeutic approaches for HES in the light of each specific molecular alteration, considering both tyrosine kinase inhibitors and monoclonal antibodies, either implemented in clinical practice or currently still under development.

Available and emerging therapies for bona fide advanced systemic mastocytosis and primary eosinophilic neoplasms

The historically poor prognosis of patients with advanced systemic mastocytosis (AdvSM) and primary eosinophilic neoplasms has shifted to increasingly favorable outcomes with the discovery of druggable targets. The multikinase/KIT inhibitor midostaurin and the highly selective KIT D816V inhibitor avapritinib can elicit marked improvements in measures of mast cell (MC) burden as well as reversion of MC-mediated organ damage (C-findings) and disease symptoms. With avapritinib, the achievement of molecular remission of KIT D816V and improved survival compared with historical therapy suggests a potential to affect disease natural history. BLU-263 and bezuclastinib are KIT D816V inhibitors currently being tested in trials of AdvSM. In the new World Health Organization and International Consensus Classifications, the category of "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase (TK) gene fusions" is inclusive of rearrangements involving PDGFRA, PDGFRB, FGFR1, JAK2, FLT3, and ETV6::ABL1. While the successful outcomes with imatinib in FIP1L1::PDGFRA-positive cases and PDGFRB-rearranged neoplasms have become the "poster children" of these disorders, the responses of the other TK-driven neoplasms to small-molecule inhibitors are more variable. The selective FGFR inhibitor pemigatinib, approved in August 2022, is a promising therapy in aggressive FGFR1-driven diseases and highlights the role of such agents in bridging patients to allogeneic transplantation. This review summarizes the data for these approved and investigational agents and discusses open questions and future priorities regarding the management of these rare diseases.

World Health Organization-defined eosinophilic disorders: 2022 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of nonhematologic (secondary or reactive) and hematologic (primary or clonal) disorders with potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 10⁹ /L. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, next generation sequencing gene assays, and flow immunophenotyping to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2016 World Health Organization endorses a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1 or with PCM1-JAK2", and the myeloproliferative neoplasm subtype, "chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS). Lymphocyte-variant HE is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (eg, < 1.5 × 10⁹ /L) without symptoms or signs of organ involvement, a watch and wait approach with close follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-α have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. Mepolizumab, an interleukin-5 (IL-5) antagonist monoclonal antibody, was recently approved by the US Food and Drug Administration for patients with idiopathic HES. The use of the IL-5 receptor antibody benralizumab, as well as other targeted therapies such as JAK2 and FGFR1 inhibitors, is under active investigation.

Systemic mastocytosis in adults: 2021 Update on diagnosis, risk stratification and management

OVERVIEW

Systemic mastocytosis (SM) results from a clonal proliferation of abnormal mast cells (MC) in extra-cutaneous organs.

DIAGNOSIS

The major criterion is presence of multifocal clusters of spindled MC in the bone marrow. Minor diagnostic criteria include elevated serum tryptase level, abnormal MC CD25 expression, and presence of KITD816V mutation.

RISK STRATIFICATION

Establishing SM subtype as per the World Health Organization classification system is an important first step. Broadly, patients either have indolent/smoldering SM (ISM/SSM) or advanced SM, the latter includes aggressive SM (ASM), SM with associated hematological neoplasm (SM-AHN), and mast cell leukemia (MCL). Identification of poor-risk mutations (ie, ASXL1, RUNX1, SRSF2, NRAS) further refines the risk stratification. Recently, clinical and hybrid clinical-molecular risk models have been developed to more accurately assign prognosis in SM patients.

MANAGEMENT

Treatment goals for ISM patients are primarily directed towards anaphylaxis prevention/symptom control/osteoporosis treatment. Patients with advanced SM frequently need MC cytoreductive therapy to ameliorate disease-related organ dysfunction. High response rates have been seen with small-molecule inhibitors that target mutant-KIT, including midostaurin (Food and Drug Administration approved) or avapritinib (investigational). Other options for MC cytoreduction include cladribine or interferon-α, although head-to-head comparisons are lacking. Treatment of SM-AHN primarily targets the AHN component, particularly if an aggressive disease such as acute myeloid leukemia is present. Allogeneic stem cell transplant can be considered in such patients, or in those with relapsed/refractory advanced SM. Imatinib has a limited therapeutic role in SM; effective cytoreduction is limited to those with imatinib-sensitive KIT mutations.

The Efficacy of Imatinib Mesylate in the Treatment of a Rare Lytic Bone Lesion Caused by Hypereosinophilic Syndrome/Chronic Eosinophilic Leukemia: A Case Report

CASE

We report a patient with hypereosinophilia-associated massive osteolytic lesion of the sacrum who was admitted to our hospital. Genetic analysis revealed that atypical eosinophilic cells were positive for FIP1-like-1-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFRA) fusion gene. Treatment was initiated with oral administration of imatinib mesylate. The patient responded rapidly to this medication with a marked reduction in eosinophilia both from the peripheral blood and FIP1L1-PDGFRA fusion gene in the bone marrow within 2 weeks, followed by gradual osteosclerotic repair of the sacrum.

CONCLUSIONS

This case study found that the drug imatinib proved very effective in the treatment of this rare condition.

COVID-19 Pneumonia or Hypereosinophilic Syndrome?

Hypereosinophilic syndromes (HESs) are a group of disorders characterized by pathological proliferation of eosinophils. Diagnostic criteria include eosinophil count of 1,500/mm³ or higher, presence of organ involvement and exclusion of other causes of eosinophilia for at least 6 months. A 69-year-old male patient was referred to the pandemic clinic with a preliminary diagnosis of coronavirus disease 2019 (COVID-19) with fever and dyspnea. Computed tomography (CT) was compatible with COVID-19, nasopharyngeal swab polymerase chain reaction (PCR) was negative for two times. He had 20,000/mm³ eosinophilia and retrospective examinations showed that he have had eosinophilia for more than 1 year. Platelet-derived growth factor receptor alpha (PDGFRα) resulted positively. After starting parenteral methylprednisolone with a dose of 1 mg/kg, he was discharged with oral maintenance therapy. In outpatient follow-up, it was observed that eosinophilic pneumonia completely regressed. HES may occur with multiple system and organ involvement and findings. In the differential diagnosis of patients presenting with heart failure, pulmonary involvement and eosinophilia, HES must definitely be considered.

Pleomorphic mastocytoma associated with loss of chromosome 5, PDGFRA, and HRAS mutations: A case of cutaneous mastocytosis with severe atypia and indolent behavior

A 21-year-old female presented with a 5-year history of an erythematous papule on her right breast. The biopsy showed a dense, dermal nodular infiltrate, extending focally into the subcutaneous tissue. The infiltrate was composed predominantly of pleomorphic cells with bi-lobed, multi-lobed, horseshoe, or ring-shaped nuclei. There was a smaller subset of monomorphous cells characterized by a round, reniform, or elongated single-lobed nucleus. Accompanying cells included few foamy histiocytes, lymphocytes, and numerous scattered eosinophils. No necrosis, vascular invasion, or ulceration was present. The pleomorphic and monomorphic granular cells were positive for Giemsa stain as well as for tryptase, CD117, CD68, CD2, and CD30 immunohistochemistry and negative for S100, CD1a, myeloperoxidase, lysozyme, and CD56. Clinical examination was negative for any additional similar lesions and serum tryptase was within normal limits. The bone marrow was not biopsied. In addition, fluorescent in situ hybridization revealed multiple clones with loss of number 5 chromosome and PDGFRA and HRAS mutations. The lesion did not recur or progress after a 6-year clinical follow-up. To our full knowledge, we report the first case of pleomorphic mastocytoma with loss of chromosome 5 and PDGFRA and HRAS mutations.

Myeloid/Lymphoid Neoplasms with Eosinophilia and TK Fusion Genes, Version 3.2021, NCCN Clinical Practice Guidelines in Oncology

Eosinophilic disorders and related syndromes represent a heterogeneous group of neoplastic and nonneoplastic conditions, characterized by more eosinophils in the peripheral blood, and may involve eosinophil-induced organ damage. In the WHO classification of myeloid and lymphoid neoplasms, eosinophilic disorders characterized by dysregulated tyrosine kinase (TK) fusion genes are recognized as a new category termed, myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB or FGFR1 or with PCM1-JAK2. In addition to these aforementioned TK fusion genes, rearrangements involving FLT3 and ABL1 genes have also been described. These new NCCN Guidelines include recommendations for the diagnosis, staging, and treatment of any one of the myeloid/lymphoid neoplasms with eosinophilia (MLN-Eo) and a TK fusion gene included in the 2017 WHO Classification, as well as MLN-Eo and a FLT3 or ABL1 rearrangement.

Loeffler's Endocarditis and Hypereosinophilic Syndrome

Loeffler's endocarditis and hypereosinophilic syndromes are a unique group of infiltrative disorders characterized by hypereosinophilia, inflammatory thrombotic, and ultimately, fibrotic involvement of the heart leading to multiple complications including valve involvement, thromboembolic phenomena, heart failure. Clinical recognition, comprehensive laboratory and multimodality imaging diagnostic workup, and early initiation of treatment have been shown to slow down the progression and promote remission. This review addresses a detailed analysis of Loeffler's endocarditis and hypereosinophilic syndromes.

Paratrabecular myelofibrosis and occult mastocytosis are strong morphological clues to suspect FIP1L1-PDGFRA translocation in hypereosinophilia

To study the clinico-haematological and histopathological characteristics of FIP1L1-PDGFRA rearranged hypereosinophilia/hypereosinophilic syndrome (F/P+ve HE/HES), a retrospective analysis of patients with F/P+ve HE diagnosed over a period of 43 months was performed. Peripheral blood smears, bone marrow aspirate (BMA) and biopsies (BMB) were reviewed in each case and; reticulin stain and immunohistochemistry for mast cell tryptase (MCT) and CD117 was performed. F/P+ve HE was diagnosed in a total of ten patients during study period. All patients were males with a median age of 36 years (23-44 years). The median duration of presenting complaints was 7 months (2 months-3 years) which included specific symptoms related to various organs (80% of cases). Anaemia, thrombocytopenia and splenomegaly were seen in 60%, 50% and 90% of the cases respectively. Mastocytosis was not obvious in BMA but identified by MCT on BMB in all cases. Myelofibrosis (grade ≥ 1) was seen in 80% of the cases and includes multifocal paratrabecular fibrosis in 50% of the biopsies. Our study shows that bone marrow mastocytosis and myelofibrosis are very useful morphological indicators to suspect F/P+ve HE and suggests the routine use of reticulin staining and MCT immunohistochemistry in all BMBs performed for the evaluation of HE/HES.

Cough in hypereosinophilic syndrome: case report and literature review

BACKGROUND

Cough and airway eosinophilic inflammation has not been highlighted in hypereosinophilic syndrome (HES).

CASE PRESENTATION

We report 2 further cases and reviewed the clinical features and treatment of HES present with cough from the literature. Both cases were middle age male, presenting with chronic cough, airway eosinophilic inflammation and hyper eosinophilia who have been previous misdiagnosed as cough-variant asthma and failed anti-asthma treatment. PDGFRA fusion gene was confirmed in one case, but not in the other case. Both had evidence of myeloproliferative features. The tyrosine kinase inhibitor, imatinib, resulted in complete resolution of eosinophilia and cough. By searching PubMed, we found 8 HES cohorts of 411 cases between 1975 and 2013, where the incidence of cough was 23.11%. Sixteen case reports of HES presented with cough as predominant or sole symptom, with nine male patients with positive PDGFRA fusion gene, who responded well to imatinib. Six of seven patients, who tested negative for the PDGFRA, responded to systemic glucocorticoids.

CONCLUSIONS

Cough and airway eosinophilic inflammation is common in some HES patients. PDGFRA+ HES patients present with chronic cough respond well to imatinib. Our case reports indicate that PDGFRA negative HES patients may respond to imatinib as well.

Contributions of Eosinophils to Human Health and Disease

The human eosinophil has long been thought to favorably influence innate mucosal immunity but at times has also been incriminated in disease pathophysiology. Research into eosinophil biology has uncovered a number of interesting contributions by eosinophils to health and disease. However, it appears that not all eosinophils from all species are created equal. It remains unclear, for example, exactly how having eosinophils benefits the human host when helminth infections in the developed world have become scarce. This review focuses on our current state of knowledge as it relates to human eosinophils. When information is lacking, we discuss lessons learned from mouse studies that may or may not directly apply to human biology and disease. It is an exciting time to be an "eosinophilosopher" because the use of biologic agents that selectively target eosinophils provides an unprecedented opportunity to define the contribution of this cell to eosinophil-associated human diseases.

Hypereosinophilic syndromes in the precision medicine era: clinical, molecular aspects and therapeutic approaches (targeted therapies)

Introduction: Hypereosinophilic syndromes are a heterogeneous group of disorders that may be associated with life-threatening organ injury as a result of tissues infiltration by eosinophils. The main goal of therapy is to mitigate eosinophil-mediated organ damage. When possible, therapy should be directed at the underlying etiology. However, even in the absence of any known cause, when organ damage is present, hypereosinophilia must be treated promptly and aggressively to reduce potential morbidity and mortality.Areas covered: Conventional therapies, including corticosteroids, hydroxyurea (hydroxycarbamide) and interferon-alpha, have shown variable efficacy and a non-negligible toxicity emphasizing the need of new therapeutic strategies based on drugs with different mechanisms of action.Expert opinion: Tyrosine kinase inhibitors have a central role among targeted therapies of hypereosinophilic syndromes. Imatinib, initially empirically used based on its activity in chronic myeloid leukemia, achieved preliminary excellent results further confirmed in large series of patients. Third-generation tyrosine kinase inhibitors such as ponatinib, while active in vitro and in vivo in animals, still deserve confirmation in properly designed clinical trials. In addition, clinical investigation on monoclonal antibodies against interleukin-5, interleukin-5Rα, IgE, and CD52 represents a promising area of research.

World Health Organization-defined eosinophilic disorders: 2019 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of non-hematologic (secondary or reactive) and hematologic (primary, clonal) disorders with potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia has generally been defined as a peripheral blood eosinophil count greater than 1.5 × 10⁹ /L, and may be associated with tissue damage. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of various tests. They include morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ-hybridization, flow immunophenotyping, and T-cell clonality assessment to detect histopathologic or clonal evidence for an acute or chronic hematolymphoid neoplasm.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2016 World Health Organization endorses a semi-molecular classification scheme of disease subtypes. This includes the major category "myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1 or with PCM1-JAK2", and the MPN subtype, "chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS). Lymphocyte-variant hypereosinophilia is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (eg, <1.5 × 10⁹ /L) without symptoms or signs of organ involvement, a watch and wait approach with close-follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Corticosteroids are first-line therapy for patients with lymphocyte-variant hypereosinophilia and HES. Hydroxyurea and interferon-alfa have demonstrated efficacy as initial treatment and in steroid-refractory cases of HES. In addition to hydroxyurea, second line cytotoxic chemotherapy agents, and hematopoietic stem cell transplantation have been used for aggressive forms of HES and CEL, with outcomes reported for limited numbers of patients. The use of antibodies against interleukin-5 (IL-5) (mepolizumab), the IL-5 receptor (benralizumab), as well as other targets on eosinophils remains an active area of investigation.

Idiopathic hypereosinophilic syndrome presenting with multiple organ damage: A case report

RATIONALE

Idiopathic hypereosinophilic syndrome (IHES) is a rare disease in which patients which present with eosinophilia-associated damage. Previous studies focused on organ damage from increased eosinophilic granulocytosis. We report IHES in a patient who presented with multiple organ damage (MOD).

PATIENT CONCERNS

A 52-year-old male presented with MOD, including myocardial damage suggestive of myocardial infarction, cardiac tamponade, respiratory failure, skin damage, and gastrointestinal damage.

DIAGNOSES

The absolute eosinophil count was 12,920/mm, much higher than occurs in other diseases associated with eosinophilia (1500/mm), and suggesting a diagnosis of IHES.

INTERVENTIONS

Prednisone combined with hydroxyurea.

OUTCOMES

At 6 months after completion of drug treatment, the patient had no chest pain or dyspnea, and the results of a blood panel, chest computed tomography, and gastroscopy were normal.

LESSONS

MOD is very rare in patients with IHES. Patients receiving prompt diagnosis and treatment have very good prognoses.

Bone marrow fibrosis associated with long-term imatinib therapy: resolution after switching to a second-generation TKI

Bone marrow fibrosis may be a late reversible toxicity of high-dose imatinib therapy in chronic myeloid leukemia.

The Role of Precision Medicine in the Diagnosis and Treatment of Patients with Rare Cancers

Rare cancers pose unique challenges for patients and their physicians arising from a lack of information regarding the best therapeutic options. Very often, a lack of clinical trial data leads physicians to choose treatments based on small case series or case reports. Precision medicine based on genomic analysis of tumors may allow for selection of better treatments with greater efficacy and less toxicity. Physicians are increasingly using genetics to identify patients at high risk for certain cancers to allow for early detection or prophylactic interventions. Genomics can be used to inform prognosis and more accurately establish a diagnosis. Genomic analysis may also expose therapeutic targets for which drugs are currently available and approved for use in other cancers. Notable successes in the treatment of previously refractory cancers have resulted. New more advanced sequencing technologies, tools for interpretation, and an increasing array of targeted drugs offer additional hope, but challenges remain.

Diagnosis and Novel Approaches to the Treatment of Hypereosinophilic Syndromes

PURPOSE OF REVIEW

Hypereosinophilic syndrome (HES) is characterized by persistent hypereosinophilia associated with end-organ damage. As our understanding of the pathogenesis of various forms of HES broadens, so does our ability to tailor steroid-sparing therapies for each subtype. The purpose of this review is to summarize recent literature related to the etiology, diagnosis, and management of HES.

RECENT FINDINGS

Mutations involved in subsets of HES can guide the choice of tyrosine kinase inhibitors beyond just imatinib. Several biologics that target interleukin-5 or its receptor have shown beneficial and selective eosinophil-reducing effects in clinical trials for asthma and other disorders including HES. Early clinical data with emerging therapies such as dexpramipexole and anti-Siglec-8 antibody show promise, but need to be confirmed in randomized trials. Several new biologics and tyrosine kinase inhibitors have been shown to lower eosinophil numbers, but more randomized trials are needed to confirm efficacy in HES.

Imatinib for the treatment of hypereosinophilic syndromes

INTRODUCTION

Hypereosinophilic syndromes (HES) encompass a group of disorders defined by sustained peripheral blood hypereosinophilia >1500/mm³ and evidence of eosinophilia-associated organ impairment. Approximately 10% of HES patients may harbor a cryptic deletion on chromosome 4 leading to formation of the FIP1L1-PDGFRA (F/P) fusion gene; these patients are diagnosed as F/P-mutated myeloid/lymphoid neoplasms with eosinophilia (MLN-eo). Areas covered: This review discusses the results of IM treatment in HES depending on mutation status. The literature on IM therapy in HES by searching PubMed for the terms 'imatinib mesylate', 'hypereosinophilic syndromes' and 'FIP1L1-PDGFRA' has been reviewed. The author's publications as well as his own experience in the field of HES treatment remain a significant contribution to this work. Expert commentary: Imatinib mesylate, a first generation tyrosine kinase inhibitor, has revolutionized the therapeutic approach to patients with hypereosinophilic syndromes and detectable F/P fusion gene. The response to IM in F/P-mutated MLN-eo is universal with minimal side effects. IM at 100mg per day induces complete molecular remission and even lower doses can be efficient to maintain durable response. Some patients may remain in continued remission after IM discontinuation. Resistance to IM is associated with dismal prognosis. IM is less effective in F/P-unmutated HES with short-lived response.

Long-term outcomes of imatinib in patients with FIP1L1/ PDGFRA associated chronic eosinophilic leukemia: experience of a single center in China

BACKGROUND

The FIP1L1/PDGFRA (F/P) fusion gene is the most common clonal genetic abnormality of chronic eosinophilic leukemia (CEL). Tyrosine kinase inhibitors (TKI), such as imatinib, have been demonstrated to be effective therapies for F/P mutated disease. The aim of this study was to analyze the treatment response and long term prognosis in patients with F/P mutated CEL.

METHODS

The clinical features and treatment responses of 33 consecutive patients with F/P mutated CEL between August 2006 and October 2014 were analyzed. The 33 cases received imatinib therapy at an initial dose of 100 mg/day (30 patients) or 200 mg/day (3 patients); the maintenance dose depended on the response condition and patient willingness. Through the follow up, the molecular responses were regularly monitored.

RESULTS

With a median follow up of 64 months, 94% of the 33 patients with F/P mutated CEL achieved a complete hematologic remission (CHR), and 97% achieved a complete molecular remission (CMR) after a median of 3 (1.5-12) months. Twenty-four cases received maintenance therapy, with a median CMR duration of 43 (5-88) months. Imatinib therapy was discontinued in 8 cases, including 4 cases who experienced relapse, and 4 patients who maintained CHR or CMR after discontinuing therapy with a median time of 47 (2-74) months. One case exhibited primary resistance with a PDGFRA T674I mutation.

CONCLUSIONS

F/P mutated CEL has an excellent long-term prognosis following imatinib therapy. A 100 mg daily dose of imatinib is sufficient to induce remission, and a single 100 mg weekly dose maintains a durable remission. A subgroup of patients may maintain a durable remission after discontinuing therapy with a CMR.

Hypereosinophilic Syndrome Presented as Acute Ischaemic Stroke and Raised Cardiac Enzymes

The hypereosinophilic syndromes (HES) are a group of disorders marked by the sustained overproduction of eosinophils, resulting in multiple organ damage. We report a 55-year-old lady presented with sudden onset of left-sided limb weakness and hypereosinophilia. Cerebral computerised tomography scan showed multiple small infarctions in bilateral corona radiata and right thalamus. A transesophageal echocardiogram revealed endomyocardial damage with mural thrombus suggesting Loeffler endocarditis. The multiple cerebral infarctions were probably due to cardiac thromboembolism. Treatment with prednisolone led to significant clinical improvement. This case illustrates hypereosinophilia should be considered in patients with multiple cerebral infarctions.

World Health Organization-defined eosinophilic disorders: 2017 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of nonhematologic (secondary or reactive) and hematologic (primary, clonal) disorders with potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia has generally been defined as a peripheral blood eosinophil count greater than 1500/mm³ and may be associated with tissue damage. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of morphologic review of the blood and marrow, standard cytogenetics, fluorescent in situ-hybridization, flow immunocytometry, and T-cell clonality assessment to detect histopathologic or clonal evidence for an acute or chronic myeloid or lymphoproliferative disorder.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2016 World Health Organization endorses a semi-molecular classification scheme of disease subtypes which includes the major category "myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1 or with PCM1-JAK2," and the "MPN subtype, chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS). Lymphocyte-variant hypereosinophilia is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g., < 1500/mm³ ) without symptoms or signs of organ involvement, a watch and wait approach with close-follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Corticosteroids are first-line therapy for patients with lymphocyte-variant hypereosinophilia and HES. Hydroxyurea and interferon-alpha have demonstrated efficacy as initial treatment and steroid-refractory cases of HES. In addition to hydroxyurea, second line cytotoxic chemotherapy agents and hematopoietic cell transplant have been used for aggressive forms of HES and CEL with outcomes reported for limited numbers of patients. The use of antibodies against interleukin-5 (IL-5) (mepolizumab), the IL-5 receptor (benralizumab), and CD52 (alemtuzumab), as well as other targets on eosinophils remains an active area of investigation.

Tyrosine Kinase Inhibitors in the Treatment of Eosinophilic Neoplasms and Systemic Mastocytosis

The World Health Organization's semimolecular classification of eosinophilias emphasizes neoplasms driven by fusion tyrosine kinases. More than 80% of patients with systemic mastocytosis carry the KIT D816V mutation, the primary driver of disease pathogenesis. Genetic annotation of these diseases is critical and affords opportunities for targeted therapy. This article discusses our understanding of the mutated tyrosine kinome of eosinophilic neoplasms and systemic mast cell disease, and the successes and limitations of available therapies. Use of tyrosine kinase inhibitors as a bridge to hematopoietic stem cell transplantation, and development of more selective and potent tyrosine kinase inhibitors is also highlighted.

Myeloid neoplasms with eosinophilia

Molecular diagnostics has generated substantial dividends in dissecting the genetic basis of myeloid neoplasms with eosinophilia. The family of diseases generated by dysregulated fusion tyrosine kinase (TK) genes is recognized by the World Health Organization (WHO) category, “Myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1, or with PCM1-JAK2.” In addition to myeloproliferative neoplasms (MPN), these patients can present with myelodysplastic syndrome/MPN, as well as de novo or secondary mixed-phenotype leukemias or lymphomas. Eosinophilia is a common, but not invariable, feature of these diseases. The natural history of PDGFRA- and PDGFRB-rearranged neoplasms has been dramatically altered by imatinib. In contrast, patients with FGFR1 and JAK2 fusion TK genes exhibit a more aggressive course and variable sensitivity to current TK inhibitors, and in most cases, long-term disease-free survival may only be achievable with allogeneic hematopoietic stem cell transplantation. Similar poor prognosis outcomes may be observed with rearrangements of FLT3 or ABL1 (eg, both of which commonly partner with ETV6), and further investigation is needed to validate their inclusion in the current WHO-defined group of eosinophilia-associated TK fusion-driven neoplasms. The diagnosis chronic eosinophilic leukemia, not otherwise specified (CEL, NOS) is assigned to patients with MPN with eosinophilia and nonspecific cytogenetic/molecular abnormalities and/or increased myeloblasts. Myeloid mutation panels have identified somatic variants in patients with a provisional diagnosis of hypereosinophilia of undetermined significance, reclassifying some of these cases as eosinophilia-associated neoplasms. Looking forward, one of the many challenges will be how to use the results of molecular profiling to guide prognosis and selection of actionable therapeutic targets.

Biological Modulators in Eosinophilic Diseases

Eosinophils can regulate local and systemic inflammation, and their presence in higher numbers appears to play an important role in the pathology of various atopic and inflammatory diseases. Eosinophil maturation, recruitment, and survival depend on several cytokine regulators, including interleukin (IL)-5, IL-4, and IL-13 as well as growth factors such as GM-CSF. Over the last decade, the approach to treating eosinophilic diseases has changed greatly. A number of biologic modulators have been developed to target eosinophilic inflammatory pathways, and their usage has resulted in variable clinical improvement in the treatment of eosinophilic-associated conditions. Novel targeted therapies that are safe and effective for treating these disorders are being investigated. This review summarizes the clinical use of biologic agents that have been studied in clinical trials or approved for treating eosinophilic diseases.

Systemic mastocytosis in adults: 2017 update on diagnosis, risk stratification and management

Disease overview:Systemic mastocytosis (SM) results from a clonal proliferation of abnormal mast cells (MC) in one or more extra-cutaneous organs.

DIAGNOSIS

The major criterion is presence of multifocal clusters of morphologically abnormal MC in the bone marrow. Minor diagnostic criteria include elevated serum tryptase level, abnormal MC expression of CD25 and/or CD2, and presence of KITD816V. Risk stratification: The 2008 World Health Organization (WHO) classification of SM has been shown to be prognostically relevant. Classification of SM patients into indolent (SM), aggressive SM (ASM), SM associated with a clonal non-MC lineage disease (SM-AHNMD) and mast cell leukemia (MCL) subgroups is a useful first step in establishing prognosis.

MANAGEMENT

SM treatment is generally palliative. ISM patients have a normal life expectancy and receive symptom-directed therapy; infrequently, cytoreductive therapy may be indicated for refractory symptoms. ASM patients have disease-related organ dysfunction; interferon-α (±corticosteroids) can control dermatological, hematological, gastrointestinal, skeletal and mediator-release symptoms, but is hampered by poor tolerability. Similarly, cladribine has broad therapeutic activity, with particular utility when rapid MC debulking is indicated; the main toxicity is myelosuppression. Imatinib has a therapeutic role in the presence of an imatinib-sensitive KIT mutation or in KITD816-unmutated patients. Treatment of SM-AHNMD is governed primarily by the non-MC neoplasm; hydroxyurea has modest utility in this setting; there is a role for allogeneic stem cell transplantation in select cases. Investigational drugs: Recent data confirms midostaurin's significant anti-MC activity in patients with advanced SM. Am. J. Hematol. 91:1147-1159, 2016. © 2016 Wiley Periodicals, Inc.

A Case of Erythroderma Secondary to Hypereosinophilia

Hypereosinophilic syndrome (HES) is a myeloproliferative disorder characterised by marked peripheral eosinophilia and end organ damage attributable to eosinophilia without secondary cause. Early recognition and treatment are essential to prevent morbidity and mortality. Cytoreduction with Steroids, Hydroxyurea and Imatinib are the main stay of treatment. Molecular studies like Fip1-like-1 fused with platelet derived growth factor receptor alpha (FIP1L1-PDGFRα) etc., are recommended in view of therapeutic implication. In this paper we report a rare case of HES developing in a lady 6 months after surgical removal of lymphangioma of spleen, which in itself is rare.

Clinical features predict responsiveness to imatinib in platelet-derived growth factor receptor-alpha-negative hypereosinophilic syndrome

BACKGROUND

With the exception of the presence of the FIP1L1-PDGFRA fusion gene, little is known about predictors of imatinib response in clinically-defined hypereosinophilic syndrome (HES).

METHODS

Subjects with FIP1L1-PDGFRA-myeloid neoplasm (FP; n =12), PDGFRA-negative HES with ≥4 criteria suggestive of a myeloid neoplasm (MHES; n =10), or steroid-refractory PDGFRA-negative HES with <4 myeloid criteria (SR; n = 5) were enrolled in a prospective study of imatinib therapy (NCT00044304: registered at clinicaltrials.gov). The primary outcome was an eosinophil count <1.5 × 109/L at one month and improvement of clinical symptoms. Clinical, molecular, and bone marrow responses to imatinib were assessed. A retrospective cohort of 18 subjects with clinically-defined HES who received imatinib (300-400 mg daily ≥ 1 month) were classified according to the criteria used in the prospective study.

RESULTS

Overall, imatinib response rates were 100% in the FP group (n = 16), 54% in the MHES group (n = 13) and 0% in the SR group (n = 16). The presence of ≥ 4 myeloid features was the sole predictor of response. After ≥ 18 months in complete remission, imatinib was tapered and discontinued in 8 FP and 1 MHES subjects. Seven subjects (6 FP, 1 MHES) remain in remission off therapy for a median of 29 months (range 14-36).

CONCLUSIONS

Clinical features of MHES predict imatinib response in PDGFRA-negative HES.

Severe Prolonged Cough as Presenting Manifestation of FIP1L1-PDGFRA+ Chronic Eosinophilic Leukaemia: A Widely Ignored Association

Chronic eosinophilic leukaemia associated with the FIP1L1-PDGFRA fusion gene (F/P+ CEL) is a rare cause of marked persistent hypereosinophilia, arising almost exclusively in male patients. Clinical presentations are heterogeneous with a higher incidence of eosinophil-mediated cardiomyopathy than in other hypereosinophilic syndrome variants. Features of chronic myeloproliferative disease are often present, including splenomegaly and elevated serum vitamin B12 levels. The diagnosis is made by fluorescence in situ hybridization (FISH) showing the deletion of the CHIC2 locus and/or RT-PCR showing the FIP1L1-PDGFRA fusion transcript. Treatment with imatinib mesylate, a tyrosine kinase inhibitor, results in rapid and complete resolution of hypereosinophilia and associated symptoms, except for those related to sub-endocardial fibrosis that may be irreversible. We report the case of a male patient in whom isolated intractable cough remained the only clinical manifestation of F/P+ CEL for 4 years. Furthermore, eosinophil autofluorescence, an as yet unreported artefact in this setting, precluded the detection of the CHIC2 deletion and further delayed diagnosis, underlining that both FISH and RT-PCR should be performed when this disease is suspected.

Eosinophilia in Hematologic Disorders

Eosinophilia in the peripheral blood can be the manifestation various medical conditions, including benign or malignant disorders. There are 3 main types of eosinophilia-associated myeloid neoplasms (MN-eos): myeloid and lymphoid neoplasms, chronic eosinophilic leukemia not otherwise specified, and idiopathic hypereosinophilic syndrome (HES). Imatinib mesylate has revolutionized the treatment of molecularly defined MN-eos, and novel agents have been successfully used to treat HES. The discovery of new, recurrent molecular alterations in patients with MN-eos may improve their diagnosis and therapy. This review focuses on the hematologist's approach to a patient with eosinophilia and treatment options for those with eosinophilic myeloid neoplasms.

Imatinib Treatment in PDGFRA-Negative Childhood Hypereosinophilic Syndrome

We report a 4-year-old female who presented with severe hypereosinophilia (215.7 K/μl) and end-organ dysfunction. Extensive evaluation including whole exome sequencing was performed, revealing no causative mutation. Initial treatment with corticosteroids, leukapheresis, and hydroxyurea decreased her absolute eosinophil count (AEC), although it remained elevated. Despite the absence of a PDGFRA mutation, an imatinib trial resulted in normalization of her AEC. Imatinib was discontinued after sustained normal counts for 1 month. AECs have remained normal for more than 1 year off therapy. This provides support for consideration of imatinib in the treatment of hypereosinophilia even in the absence of a known tyrosine kinase mutation.

Eosinophilia: a pragmatic approach to diagnosis and treatment

Eosinophilia is associated with a wide variety of allergic, rheumatologic, infectious, neoplastic, and rare idiopathic disorders. Clinical manifestations range from benign asymptomatic presentations to life-threatening complications, including endomyocardial fibrosis and thromboembolism. The prognosis and choice of treatment depend not only on the degree of eosinophilia and severity of organ involvement, but also on the etiology of the eosinophilia. Unfortunately, despite recent advances in molecular and immunologic techniques, the etiology remains unproven in the overwhelming majority of cases. This review presents a practical approach to the diagnosis and treatment of patients presenting with unexplained marked eosinophilia. A brief overview of the mechanisms of eosinophilia and eosinophil pathogenesis is also provided.

World Health Organization-defined eosinophilic disorders: 2015 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of non-hematologic (secondary or reactive) and hematologic (primary, clonal) disorders with potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia has generally been defined as a peripheral blood eosinophil count greater than 1,500/mm(3) and may be associated with tissue damage. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of morphologic review of the blood and marrow, standard cytogenetics, fluorescent in situ-hybridization, flow immunocytometry, and T-cell clonality assessment to detect histopathologic or clonal evidence for an acute or chronic myeloid or lymphoproliferative disorder.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2008 World Health Organization establishes a semi-molecular classification scheme of disease subtypes including 'myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR1', chronic eosinophilic leukemia, not otherwise specified, (CEL, NOS), lymphocyte-variant hypereosinophilia, and idiopathic hypereosinophilic syndrome (HES), which is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of the therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g. < 1,500/mm(3) ) without symptoms or signs of organ involvement, a watch and wait approach with close-follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Corticosteroids are first-line therapy for patients with lymphocyte-variant hypereosinophilia and HES. Hydroxyurea and interferon-alpha have demonstrated efficacy as initial treatment and steroid-refractory cases of HES. In addition to hydroxyurea, second line cytotoxic chemotherapy agents and hematopoietic cell transplant have been used for aggressive forms of HES and CEL with outcomes reported for limited numbers of patients. Although clinical trials have been performed with anti IL-5 (mepolizumab) and anti-CD52 (alemtuzumab) antibodies, their therapeutic role in primary eosinophilic diseases and HES has yet to be established.

Comparison of two leukocytapheresis protocols in a case of idiopathic hypereosinophilic syndrome

BACKGROUND

Hypereosinophilic syndrome (HEOS) is rare, and the efficacy of leukocytapheresis in this context is unclear. We here report the successful treatment of a patient with idiopathic HEOS with four leukocytapheresis procedures using two protocols.

CASE

A 4-year-old female presented with cardiac and respiratory dysfunction, and WBC of 225 K/μL with 96% eosinophils. Leukocytapheresis was started after initiation of methylprednisolone and hydroxyurea. She received two leukocytapheresis with polymorphonuclear cell (PMN) protocol, followed by initiation of imatinib therapy, then two leukocytapheresis with mononuclear cell (MNC) protocol. After the fourth leukocytapheresis, her WBC decreased to 69 K/μL with 82% eosinophils. She was discharged on hospital day 21 under stable condition with WBC of 22 K/μL with 86% eosinophils. WBC count and eosinophil percentage continued to decrease, and were 6.4 K/μL and 52% by 2 weeks and 3.9 K/μL and 4.9% by 3 months after discharge, respectively.

FINDINGS

WBC and absolute eosinophil (aEO) counts decreased by an average of 29.0 and 30.4% per leukocytapheresis, respectively. Normalized to estimated blood volume, procedures with PMN and MNC protocols changed, on average, WBC by -10.7 and -12.1%, aEO by -10.4 and -13.4%, platelet by -8.1 and -19.2%, and fluid balance by -129 and -47 mL, respectively.

CONCLUSION

Leukocytapheresis was effective in decreasing WBC and aEO counts in HEOS, with PMN and MNC protocols achieving similar reductions. However, PMN protocol resulted in greater negative fluid balance and MNC protocol resulted in greater platelet loss. J. Clin. Apheresis 31:481-489, 2016. © 2015 Wiley Periodicals, Inc.

How I treat hypereosinophilic syndromes

Hypereosinophilic syndromes (HESs) are a group of rare disorders characterized by peripheral blood eosinophilia of 1.5 × 10(9)/L or higher and evidence of end organ manifestations attributable to the eosinophilia and not otherwise explained in the clinical setting. HESs are pleomorphic in clinical presentation and can be idiopathic or associated with a variety of underlying conditions, including allergic, rheumatologic, infectious, and neoplastic disorders. Moreover, the etiology of the eosinophilia in HESs can be primary (myeloid), secondary (lymphocyte-driven), or unknown. Although corticosteroids remain the first-line therapy for most forms of HESs, the availability of an increasing number of novel therapeutic agents, including tyrosine kinase inhibitors and monoclonal antibodies, has necessarily altered the approach to treatment of HESs. This review presents an updated treatment-based approach to the classification of patients with presumed HES and discusses the roles of conventional and novel agents in the management of these patients.

Systemic mastocytosis in adults: 2015 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Systemic mastocytosis (SM) results from a clonal proliferation of abnormal mast cells (MC) in one or more extracutaneous organs.

DIAGNOSIS

The major criterion is presence of multifocal clusters of morphologically abnormal MC in the bone marrow. Minor diagnostic criteria include elevated serum tryptase level, abnormal MC expression of CD25 and/or CD2, and presence of KITD816V.

RISK STRATIFICATION

The 2008 World Health Organization classification of SM has been shown to be prognostically relevant. Classification of SM patients into indolent SM (ISM), aggressive SM (ASM), SM associated with a clonal non-MC lineage disease (SM-AHNMD), and mast cell leukemia (MCL) subgroups is a useful first step in establishing prognosis.

MANAGEMENT

SM treatment is generally palliative. ISM patients have a normal life expectancy and receive symptom-directed therapy; infrequently, cytoreductive therapy may be indicated for refractory symptoms. ASM patients have disease-related organ dysfunction; interferon-α (+/-corticosteroids) can control dermatological, hematological, gastrointestinal, skeletal, and mediator-release symptoms, but is hampered by poor tolerability. Similarly, cladribine has broad therapeutic activity, with particular utility when rapid MC debulking is indicated; the main toxicity is myelosuppression. Imatinib has a therapeutic role in the presence of an imatinib-sensitive KIT mutation or in KITD816-unmutated patients. Treatment of SM-AHNMD is governed primarily by the non-MC neoplasm; hydroxyurea has modest utility in this setting; there is a role for allogeneic stem cell transplantation in select cases. Investigational Drugs: Recent data confirms midostaurin's significant anti-MC activity in patients with advanced SM.

[FIP1L1-PDGFRА-positive myeloproliferative disease with eosinophilia: A rare case with multiple organ dysfunction and a response to tyrosine kinase inhibitor therapy]

The described case of FIP1L1-PDGFRА-positive myeloproliferative disease is characterized by an atypical aggressive course to develop severe specific complications as injuries to the brain, heart, lung, and intestine. Pathogenetic therapy with imatinib could stabilize a patient's state, but failed to produce a complete hematological response. Switching from imatinib to dasatinib could produce sustained clinical, hematological, and molecular remissions.

Idiopathic hypereosinophilic syndrome: a rare cause of erythroderma

BACKGROUND

Idiopathic hypereosinophilic syndrome (HES) is a rare and potentially lethal disorder characterized by persistently elevated eosinophil counts without any underlying causes. Two variants, the myeloproliferative and lymphocytic hypereosinophilic syndrome, have been identified. The symptoms are variable and related to the organs involved (cardiovascular system, skin, central and peripheral nervous system, gastrointestinal tract, eyes). Skin lesions can be the dominating and/or presenting symptom in about 50% of patients.

MAIN OBSERVATIONS

We describe a 54-year-old man with a 12-year history of skin lesions, clinically consistent with psoriasis and psoriatic erythroderma. The patient was treated with methotrexate with no response. He experienced intense pruritus, dry/coarse skin and palmoplantar hyperkeratosis. Histopathology showed spongiotic dermatitis with no epidermotropism. Inflammatory infiltrates in upper dermis consisted predominantly of lymphocytes and eosinophils. Peripheral and tissue eosinophilia, immunophenotyping, and results of FIP1L1-PDGFRA gene analysis were suggestive of lymphocytic HES. The patient was treated with hydroxycarbamide (1 g/day), prednisolone (40 mg/day) and antihistamines with improvement.

CONCLUSIONS

HES requires early treatment to prevent severe damage of targeted organs. The pleomorphic dermatological manifestations may delay the diagnosis. This case shows the importance of wide differential diagnosis of erythroderma. In this article we discuss the diagnostic criteria, the recommended work-up and management of idiopathic hypereosinophilic syndrome variants.

Targeting platelet-derived growth factor as a therapeutic approach in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal lung disease characterized by the proliferation of fibroblasts and deposition of extracellular matrix. Since the prognosis of IPF is still poor, novel therapeutic modalities are strongly required. For this reason, to find molecular target for therapy of IPF is of much importance. The recent understanding of pathogenesis in IPF indicates the critical role of alveolar epithelial type II cells (AECII) and fibroblasts. Although the detailed mechanisms involved in IPF is still unclear, various profibrotic mediators which are produced by the injured AECII are thought to play a role in the progression of pulmonary fibrosis via stimulating fibroblasts. Among them, platelet-derived growth factor (PDGF) is one of critical growth factors by stimulating the proliferation and migration of fibroblasts. In this review, we discuss the role of PDGF in pulmonary fibrosis and the possibility as a therapeutic target for IPF.

Eosinophilia in mast cell disease

Eosinophils and mast cells coexist in clonal and nonclonal disorders. The interplay between these cells is complex and not fully understood. Discussed are both allergic/nonclonal disorders in which both cell types are increased in number are likely to play a role in pathogenesis and clonal disorders in which both cell types are affected and play key roles in pathogenesis. Finally, some treatment options, keeping both disorders in mind, are discussed. Future directions in thinking about these disorders are also briefly explored.

World Health Organization-defined eosinophilic disorders: 2014 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

The eosinophilias encompass a broad range of nonhematologic (secondary or reactive) and hematologic (primary, clonal) disorders with potential for end-organ damage.

DIAGNOSIS

Hypereosinophilia (HE) has generally been defined as a peripheral blood eosinophil count greater than 1,500/mm(3) and may be associated with tissue damage. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of morphologic review of the blood and marrow, standard cytogenetics, fluorescent in situ hybridization, flow immunocytometry, and T-cell clonality assessment to detect histopathologic or clonal evidence for an acute or chronic myeloid or lymphoproliferative disorder.

RISK STRATIFICATION

Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2008 World Health Organization establishes a semimolecular classification scheme of disease subtypes including "myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR1', chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS), lymphocyte-variant HE, and idiopathic hypereosinophilic syndrome (HES), which is a diagnosis of exclusion.

RISK-ADAPTED THERAPY

The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g., <1,500/mm(3)) without symptoms or signs of organ involvement, a watch and wait approach with close-follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these diseases to imatinib. Corticosteroids are first-line therapy for patients with lymphocyte-variant HE and HES. Hydroxyurea and interferon-alpha have demonstrated efficacy as initial treatment and steroid-refractory cases of HES. In addition to hydroxyurea, second-line cytotoxic chemotherapy agents and hematopoietic cell transplant have been used for aggressive forms of HES and CEL with outcomes reported for limited number of patients. Although clinical trials have been performed with anti-IL-5 (mepolizumab) and anti-CD52 (alemtuzumab) antibodies, their therapeutic role in primary eosinophilic diseases and HES has yet to be established.

Targeting mast cells in inflammatory diseases

Although mast cells have long been known to play a critical role in anaphylaxis and other allergic diseases, they also participate in some innate immune responses and may even have some protective functions. Data from the study of mast cell-deficient mice have facilitated our understanding of some of the molecular mechanisms driving mast cell functions during both innate and adaptive immune responses. This review presents an overview of the biology of mast cells and their potential involvement in various inflammatory diseases. We then discuss some of the current pharmacological approaches used to target mast cells and their products in several diseases associated with mast cell activation.