Efficacy of imatinib mesylate in the treatment of idiopathic hypereosinophilic syndrome

An Intriguing Case of Eosinophilia with FIP1L1/PDGFRA Rearrangement Who Presented as Thrombotic Thrombocytopenic Purpura

Myeloid neoplasm with eosinophilia and FIP1-like-1-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFRA) rearrangement is a multi-organ disease with diverse clinical presentation. Thrombotic thrombocytopenic purpura (TTP) is characterized by the concomitant occurrence of often severe thrombocytopenia, microangiopathic hemolytic anemia, and a variable degree of ischemic organ damage. To our knowledge, only one case of eosinophilia with FIP1L1-PDGFRA rearrangement presented as a case of thrombotic thrombocytopenic purpura reported in the literature. We herein report a case of a young male patient with hypereosinophilic syndrome and FIP1L1-PDGFRA rearrangement who presented with asthma, transient ischemic attacks (TIA), and confusion. He had an acquired TTP that was successfully treated with plasma exchanges (PLEX), corticosteroids, rituximab, and later with the addition of imatinib mesylate (Gleevec, Novartis). He remains in complete remission on imatinib 100 mg daily for more than 28 months of follow-up.

Efficacy of Imatinib Mesylate in a Patient with Idiopathic Hypereosinophilic Syndrome and Severe Heart Involvement

Idiopathic hypereosinophilic syndrome (HES) is a rare, chronic hematological disease mainly characterized by unexplained prolonged eosinophilia, with frequent evidence of secondary organ damage. Treatment with steroids, chemotherapy, interferon-alpha (IFN-α), or imatinib-mesylate may improve the prognosis.

Here we describe the case of a young male patient with a six-year history of HES and severe heart involvement who, after unsuccessful treatment attempts with steroids, hydroxyurea and IFN-α, had a prompt, clinical and hematological complete remission following administration of imatinib. As his cardiac function also markedly improved, he was considered for heart transplant. However, seven years after the onset of the disease and four months after the termination of imatinib treatment the patient died of a cerebral hemorrhage that occurred during an episode of acute respiratory sepsis. Imatinib has been previously reported to be effective in some hematological conditions with no evidence of the BCR/ABL transcript. The mechanisms that are probably involved in the response to imatinib in HES are also discussed.

A Test Utilization Approach to the Diagnostic Workup of Isolated Eosinophilia in Otherwise Morphologically Unremarkable Bone Marrow: A Single Institutional Experience

OBJECTIVES

Determine ancillary test utilization for the workup of isolated eosinophilia in otherwise morphologically unremarkable bone marrow (BM).

METHODS

We evaluated BM ancillary testing performed in cases with isolated eosinophilia and otherwise morphologically unremarkable BM. Cases with abnormal morphology (eg, dysplasia, basophilia) and/or findings suggestive of a disorder (eg, unexplained thromboses, lymphoma) are specifically excluded.

RESULTS

A total of 132 cases met inclusion criteria. Ten cases had an ancillary testing abnormality that warranted a more specific hematologic diagnosis: four cases of lymphocytic variant of hypereosinophilic syndrome, three cases of myeloid neoplasm with PDGFRA rearrangement, and one case each of myeloid neoplasm with PDGFRB rearrangement, chronic eosinophilic leukemia, and morphologically occult systemic mastocytosis. No cases revealed a cryptic PDGFRB or BCR/ABL1 rearrangement or JAK2 V617F mutation.

CONCLUSIONS

Findings from our institutional experience support initial testing in isolated eosinophilia with otherwise unremarkable BM to include PDGFRA rearrangement, tryptase/CD25 immunohistochemistry, cytogenetics, and T-cell flow cytometry/receptor gene rearrangement. This approach achieves diagnostic quality and test utilization efficiency in our clinical practice.

Fatal Outcome of Imatinib in a Patient with Idiopathic Hypereosinophilic Syndrome

Cytokine storm is a poorly explained clinical entity caused by an undesired and aggrandized immune system response leading to unregulated activation of the proinflammatory cascade, often contributing to multisystem organ failure and even death. Its potentially diverse etiologies and sepsis-like presentation have made it even more challenging to diagnose, and so far, no well-established treatment protocol has been proposed. Its association with certain medications, especially with monoclonal antibodies, has well been reported in literature. To the best of our knowledge, so far, no previous case of cytokine storm associated with imatinib has been reported. We herein present a case report of a 77-year-old male with a past medical history of hypereosinophilic syndrome who developed acute fatal cytokine storm following treatment with imatinib. This study highlights a life-threatening complication of the medication that may be underrecognized.

Involvement of platelet-derived growth factor ligands and receptors in tumorigenesis

Platelet-derived growth factor (PDGF) isoforms and their receptors have important roles during embryogenesis, particularly in the development of various mesenchymal cell types in different organs. In the adult, PDGF stimulates wound healing and regulates tissue homeostasis. However, overactivity of PDGF signalling is associated with malignancies and other diseases characterized by excessive cell proliferation, such as fibrotic conditions and atherosclerosis. In certain tumours, genetic or epigenetic alterations of the genes for PDGF ligands and receptors drive tumour cell proliferation and survival. Examples include the rare skin tumour dermatofibrosarcoma protuberance, which is driven by autocrine PDGF stimulation due to translocation of a PDGF gene, and certain gastrointestinal stromal tumours and leukaemias, which are driven by constitute activation of PDGF receptors due to point mutations and formation of fusion proteins of the receptors, respectively. Moreover, PDGF stimulates cells in tumour stroma and promotes angiogenesis as well as the development of cancer-associated fibroblasts, both of which promote tumour progression. Inhibitors of PDGF signalling may thus be of clinical usefulness in the treatment of certain tumours.

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.

Imatinib in systemic mastocytosis: a phase IV clinical trial in patients lacking exon 17 KIT mutations and review of the literature

Resistance to imatinib has been recurrently reported in systemic mastocytosis (SM) carrying exon 17 KIT mutations. We evaluated the efficacy and safety of imatinib therapy in 10 adult SM patients lacking exon 17 KIT mutations, 9 of which fulfilled criteria for well-differentiated SM (WDSM). The World Health Organization 2008 disease categories among WDSM patients were mast cell (MC) leukemia (n = 3), indolent SM (n = 3) and cutaneous mastocytosis (n = 3); the remainder case had SM associated with a clonal haematological non-MC disease. Patients were given imatinib for 12 months -400 or 300 mg daily depending on the presence vs. absence of > 30% bone marrow (BM) MCs and/or signs of advanced disease-. Absence of exon 17 KIT mutations was confirmed in highly-purified BM MCs by peptide nucleic acid-mediated PCR, while mutations involving other exons were investigated by direct sequencing of purified BM MC DNA. Complete response (CR) was defined as resolution of BM MC infiltration, skin lesions, organomegalies and MC-mediator release-associated symptoms, plus normalization of serum tryptase. Criteria for partial response (PR) included ≥ 50% reduction in BM MC infiltration and improvement of skin lesions and/or organomegalies. Treatment was well-tolerated with an overall response rate of 50%, including early and sustained CR in four patients, three of whom had extracellular mutations of KIT, and PR in one case. This later patient and all non-responders (n = 5) showed wild-type KIT. These results together with previous data from the literature support the relevance of the KIT mutational status in selecting SM patients who are candidates for imatinib therapy.

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.

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.

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.

Eosinophils and cancer

Eosinophils have long been known to infiltrate tumors, and in most cases, this is associated with an improved prognosis. However, the reasons behind this infiltration and the mechanism of action of the eosinophil have remained elusive. In this article, we explore the biology of eosinophils and examine their function in homeostasis and disease states, specifically focusing on what is currently known about the association of the eosinophil with cancer.

Targeting the PDGF signaling pathway in tumor treatment

Platelet-derived growth factor (PDGF) isoforms and PDGF receptors have important functions in the regulation of growth and survival of certain cell types during embryonal development and e.g. tissue repair in the adult. Overactivity of PDGF receptor signaling, by overexpression or mutational events, may drive tumor cell growth. In addition, pericytes of the vasculature and fibroblasts and myofibroblasts of the stroma of solid tumors express PDGF receptors, and PDGF stimulation of such cells promotes tumorigenesis. Inhibition of PDGF receptor signaling has proven to useful for the treatment of patients with certain rare tumors. Whether treatment with PDGF/PDGF receptor antagonists will be beneficial for more common malignancies is the subject for ongoing studies.

Review of current classification, molecular alterations, and tyrosine kinase inhibitor therapies in myeloproliferative disorders with hypereosinophilia

Recent advances in our understanding of the molecular mechanisms underlying hypereosinophilia have led to the development of a ‘molecular’ classification of myeloproliferative disorders with eosinophilia. The revised 2008 World Health Organization classification of myeloid neoplasms included a new category called “myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1.” Despite the molecular heterogeneity of PDGFR (platelet-derived growth factor receptor) rearrangements, tyrosine kinase inhibitors at low dose induce rapid and complete hematological remission in the majority of these patients. Other kinase inhibitors are promising. Further discoveries of new molecular alterations will direct the development of new specific inhibitors. In this review, an update of the classifications of myeloproliferative disorders associated with hypereosinophilia is discussed together with open and controversial questions. Molecular mechanisms and promising results of tyrosine kinase inhibitor treatments are reviewed.

Effects of imatinib mesylate on pulmonary allergic vasculitis in a murine model

Objectives

Imatinib mesylate (IM) is a potent and specific tyrosine inhibitor and has been reported to inhibit mesenchymal cell proliferation in pulmonary fibrosis. In the present study, we examine the effects of IM on vascular remodeling in a murine model of allergic vasculitis with eosinophil infiltration.

Methods

C57BL/6 mice were sensitized with ovalbumin (OVA) and alum. The positive controls were exposed to aerosolized OVA daily for 7 days. IM treated mice with exposure to OVA were administered IM in parallel with daily exposure to aerosolized OVA for 7 days. On the 7th day, bronchoalveolar lavage (BAL) was performed and the lungs were excised for pathological analysis. Cell differentials were determined and the concentrations of cytokines in the BAL fluid (BALF) were measured. Semi-quantitative analysis of pathological changes in the pulmonary arteries was evaluated according to the criteria of severity of vasculitis. Immunohistochemistry for Ki-67 to detect proliferating cells was performed.

Results

The number of eosinophils in BALF was reduced significantly in the IM-treated group compared to the positive control. There was no significant difference in the concentrations of interleukin (IL)-2, IL-4, IL-5, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, tumor growth factor (TGF)-β or platelet-derived growth factor in the BAL fluid between the positive control and the IM-treated group. The pathological scores of vasculitis and the ratio of Ki-67-positive intra-luminal cells were reduced significantly in the IM-treated group compared to the control group after OVA exposure.

Conclusion

IM-suppressed pulmonary vascular remodeling in a murine model of allergic vasculitis with eosinophil infiltration.

Eosinophilic disorders in various diseases

Peripheral and tissue eosinophilia are usually associated with a variety of inflammatory, malignant, and infectious conditions. As the presence of eosinophils in the tissues may cause significant cellular damage to vital organs such as the heart, tissue eosinophilia should be diagnosed and treated promptly. One operative way to evaluate eosinophilic disorders is to classify them into extrinsic and intrinsic. While extrinsic eosinophilic disorders are usually due to the production of eosinopoietic factors derived from T cells or tumor cells, the intrinsic types generally are the result of genetic mutations in the eosinophilic lineage. As we understand more the biology of eosinophils, only a few eosinophilic disorders remain idiopathic. The purpose of this article is to help the clinician classify in an operational manner most eosinophilic disorders, using the extrinsic and intrinsic model. This may facilitate not only a better understanding of the role of eosinophils in these disorders, but also help the systematic clinical work-up and potential treatment of affected patients.

Monitoring disease response in chronic-phase chronic myeloid leukemia: the age of molecular assays?

An 80-year-old man has newly diagnosed chronic myeloid leukemia. His BM and blood examination at diagnosis confirms chronic-phase disease, with the Philadelphia chromosome as the sole cytogenetic abnormality. He has intermediate Sokal and Hasford risk,1 and is started on imatinib 600 mg once daily. He lives 5 hours away from the nearest specialist hematology service and prefers followup with his local physician, who cannot perform BM examinations. In patients such as this, is it acceptable to monitor his therapeutic response solely with molecular studies of his peripheral blood?

Mepolizumab in eosinophilic disorders

Mepolizumab (Bosatria(®), GlaxoSmithKline) is a biologic agent developed to treat asthma. It represents a humanized monoclonal antibody of IgG1 κ type, which targets human IL-5 and thus prevents its interaction with the α-chain of the IL-5 receptor. To date, it has not been approved for use in any eosinophil-related disorder; however, several studies have suggested some therapeutic benefit across a spectrum of eosinophil-related disorders. This article evaluates the currently available preclinical and clinical studies, and the impact of mepolizumab against a variety of eosinophilic disorders.

A patient with shortness of breath and bilateral pulmonary infiltrates

Eosinophilic disorders are rare and clinically challenging diagnoses. In part, the challenge comes from the fact that some classifications of eosinophilic diseases have been based on the site of eosinophilic infiltration whereas others have been based on the actual number of blood eosinophils present. We describe a 54-year-old woman who had a history of asthma and presented with shortness of breath and eosinophilia. The differential diagnosis is broad and includes infectious diseases, inflammatory conditions such as Churg-Strauss syndrome, and hematologic conditions such as hypereosinophilic syndrome. We describe the diagnostic challenges inherent in such a presentation and also the changing landscape of disease labels in light of our evolving ability to diagnose genetic abnormalities.

The hypereosinophilic syndromes: current concepts and treatments

The hypereosinophilic syndromes (HES) encompass a spectrum of diseases that have increased blood eosinophils and tissue damage in common. The clinical manifestations are protean and may involve any organ system, but especially the skin. Our understanding of these diseases has drastically changed over the past 15 years, along with new classifications that characterize patients with marked eosinophilia. One HES variant, myeloproliferative, is actually chronic eosinophilic leukaemia with a unique genetic marker, FIP1L1-PDGFRA. Such patients are well-controlled by administration of the kinase inhibitor, imatinib, and remissions appear durable with continued imatinib therapy. FIP1L1-PDGFRA is expressed in several cell lineages, thus explaining increases in neutrophils and mast cells in HES. The lymphocytic HES variant is associated with T-cell clones producing interleukin-5 (IL-5) and can evolve into lymphoma. While myeloproliferative and lymphocytic HES are well established and permit elimination of the term, idiopathic, to these varieties, most HES patients do not fall into these categories and are classified as complex (using the 2006 Workshop Report). A recent study showed that a monoclonal antibody to IL-5, mepolizumab, reduced glucocorticoid therapy in HES patients who did not possess the FIP1L1-PDGFRA mutation while controlling eosinophilia and preventing recurrence or progression of tissue damage. These advances augur well for continued progress in the understanding and treatment of HES.

Successful treatment of myeloid neoplasms associated with PDGFRA rearrangement with imatinib mesylate

Hypereosinophilic syndromes (HES) constitute a rare and heterogeneous group of disorders, defined as persistent and marked blood eosinophilia associated with evidence of eosinophil-induced organ damage. Cardiac dysfunction is the most frequent result of end-organ damage and is the major cause of morbidity and mortality among patients with HES. Despite patients with FIP1-like-1-platelet-derived growth factor alpha (FIP1L1-PDGFRA) associated HES (myeloid neoplasms associated with PDGFRA rearrangement) have been shown to respond to low-dose imatinib with a complete and durable hematological and cytogenetic remission, influences of imatinib on clinical manifestations related to hypereosinophilia heart involvement are variable. Here we describe the case of a young male patient with severe heart involvement who had a prompt, clinical and hematological complete remission following administration of imatinib. However, as endomyocardial fibrosis and related loss of function are deteriorated after initiation of imatinib therapy, valvular replacement and tricuspid annuloplasty had to perform to restore his heart function. Our finding concurs with recent reports that severe heart involvement was irreversible with imatinib treatment.

Imatinib has limited therapeutic activity for hypereosinophilic syndrome patients with unknown or negative PDGFRalpha mutation status

Hypereosinophilic syndrome (HES) is characterized by sustained non-clonal blood and tissue eosinophilia, leading to end-organ damage. With a molecular/cytogenetic clonality marker, the disease is classified as chronic eosinophilic leukemia (CEL). Efficacy of imatinib mesylate is well established in CEL with FIP1L1-platelet-derived growth factor-alpha (PDGFRalpha) rearrangement. We treated with imatinib 18 HES patients (11 PDGFRalpha-negative and 7 PDGFRalpha-status unknown). One patient with unknown PDGFRalpha status achieved complete hematologic response, and two (one PDGFRalpha negative and one status unknown) achieved partial hematologic response. Our results confirm low response rate to imatinib in HES patients with unknown or negative PDGFRalpha status, and underscore the need for new therapeutic options for this disorder.

Phase II study of dasatinib in Philadelphia chromosome-negative acute and chronic myeloid diseases, including systemic mastocytosis

PURPOSE

Molecular characterization of Philadelphia chromosome-negative (Ph-) chronic myeloproliferative disorders, such as systemic mastocytosis (SM), has provided a clear rationale for investigating novel targeted therapies. The tyrosine kinase (TK) inhibitor dasatinib is 325-fold more potent against Bcr-Abl TK than imatinib in vitro, significantly inhibiting wild-type KIT and platelet-derived growth factor receptor beta TKs, and is active against cells carrying the mutant KIT-D816V gene.

EXPERIMENTAL DESIGN

In this phase 2, open-label study, the efficacy of dasatinib (140 mg/d) was investigated in 67 patients with various Ph- myeloid disorders, including SM (n = 33; 28 KIT-D816V positive).

RESULTS

The overall response rate to dasatinib in patients with SM was 33%. Only two patients, one with SM-myelofibrosis and one with SM-chronic eosinophilic leukemia, achieved complete response (elimination of mastocytosis) lasting for 5 and 16 months, respectively. Both patients were negative for KIT-D816V mutation, had low tryptase levels, abnormal WBC counts, and anemia, and had failed prior therapy with erythropoietin. Additional nine SM patients had symptomatic response, lasting 3 to 18+ months. Complete responses were achieved in two other patients (acute myeloid leukemia and hypereosinophilic syndrome). No responses were observed among patients with myelodysplastic syndromes and primary myelofibrosis. The majority of adverse events were grade 1/2.

CONCLUSION

These data show that dasatinib therapy may benefit a selected group of SM patients, primarily by improving their symptoms, but it does not eliminate the disease in the patients with KIT-D816V mutation.

Therapeutic options for patients with clonal and idiopathic hypereosinophia

BACKGROUND

The hypereosinophilic syndrome (HES) comprises a heterogeneous group of disorders characterized by chronic, unexplained hypereosinophilia with organ involvement. The discovery of novel molecular targets has changed the therapeutic paradigm in HES.

OBJECTIVE

This article reviews the current medical management of patients with clonal and idiopathic hypereosinophilia with a particular emphasis on emerging new targeted therapies.

METHODS

The information contained in this review was obtained from public sources such as journals and scientific meeting abstracts. The opinions expressed in this review are solely those of the authors.

RESULTS/CONCLUSION

The development of imatinib-resistant mutations in the FIP1L1-PDGFR-alpha kinase domain has spurred the development of an array of new tyrosine kinase inhibitors. Moreover, the elucidation of the role of interleukin-5 in the pathogenesis of the lymphocytic variant of HES and the fact that CD52 is expressed on the surface of eosinophils and T cells have led to the clinical use of monoclonal antibodies such as mepolizumab, reslizumumab, and alemtuzumab for the treatment of different forms of hypereosinophilia.

Eosinophils: biological properties and role in health and disease

Eosinophils are pleiotropic multifunctional leukocytes involved in initiation and propagation of diverse inflammatory responses, as well as modulators of innate and adaptive immunity. In this review, the biology of eosinophils is summarized, focusing on transcriptional regulation of eosinophil differentiation, characterization of the growing properties of eosinophil granule proteins, surface proteins and pleiotropic mediators, and molecular mechanisms of eosinophil degranulation. New views on the role of eosinophils in homeostatic function are examined, including developmental biology and innate and adaptive immunity (as well as their interaction with mast cells and T cells) and their proposed role in disease processes including infections, asthma, and gastrointestinal disorders. Finally, strategies for targeted therapeutic intervention in eosinophil-mediated mucosal diseases are conceptualized.

Management of hypereosinophilic syndrome: a prospective study in the era of molecular genetics

Hypereosinophilic syndrome (HES) is a heterogeneous group of disorders characterized by unexplained persistent primary eosinophilia causing end-organ damage. We conducted a prospective cohort study of patients fulfilling the diagnostic criteria for HES. Of 20 patients considered eligible for the study, 2 were found to have clonal myeloid disorders, limiting the diagnosis of "true" HES to 18 patients. No patient carried the FIP1L1-PDGFRA fusion gene or other imatinib-responsive translocations. A clonal interleukin-5-producing T-cell population was not detected in any patient. Common manifestations at presentation were pulmonary, cutaneous, and neurologic involvement; serositis; and gastrointestinal involvement. Only 3 patients developed cardiac involvement. Fifteen of the HES patients were administered first-line combined treatment with steroids and hydroxyurea. Nine patients achieved complete response, while 6 attained only partial response. Imatinib was administered to 3 HES patients who had been pretreated with steroids, resulting in complete hematologic and clinical response in 2 patients and no response at all in 1. Further treatment of the latter patient with steroids and hydroxyurea also proved ineffective. We conclude that the therapeutic approach should be individualized according to molecular findings. We consider the coadministration of corticosteroids and hydroxyurea to be an effective combination for the treatment of FIP1L1-PDGFRA-negative HES.

Gastrointestinal eosinophilia

Gastrointestinal eosinophilia, a broad term for abnormal eosinophil accumulation in the gastrointestinal tract, involves many different disease identities. These diseases include primary eosinophil associated gastrointestinal diseases, gastrointestinal eosinophilia in hypereosinophilic syndrome, and all gastrointestinal eosinophilic states associated with known causes. Each of these diseases has its unique features but there is no absolute boundary between them. All three groups of gastrointestinal eosinophila are described in this article, although the focus is on primary gastrointestinal eosinophilia.

KIT D816V-associated systemic mastocytosis with eosinophilia and FIP1L1/PDGFRA-associated chronic eosinophilic leukemia are distinct entities

BACKGROUND

The broad and overlapping clinical manifestations of D816V KIT-associated systemic mastocytosis with eosinophilia and FIP1L1/PDGFRA-associated chronic eosinophilic leukemia (CEL), coupled with the increase in activated eosinophils and mast cells seen in both disorders, have led to confusion in the nomenclature. It is of paramount importance, however, to distinguish between these 2 groups of patients because of differences in clinical sequelae, prognoses, and selection of treatment.

OBJECTIVE

We thus sought to identify clinical and laboratory features that could be used to distinguish these 2 diagnoses.

METHODS

We compared 12 patients with D816V-positive systemic mastocytosis with eosinophilia with 17 patients with FIP1L1/PDGFRA-positive CEL. Distinguishing features were used to create a risk factor scoring system.

RESULTS

This system correctly classified 16 of 17 FIP1L1/PDGFRA-positive patients with CEL and all 12 patients with systemic mastocytosis with eosinophilia. Thirty-four FIP1L1/PDGFRA-positive patients described in the literature were also classified using this system, and although a complete set of data was not available for any of the historical patients, 21 were correctly classified.

CONCLUSION

These results reinforce the hypothesis that the FIP1L1/PDGFRA gene fusion and D816V-KIT mutation cause distinct clinical syndromes.

CLINICAL IMPLICATIONS

This novel diagnostic approach should prove helpful in clinical practice in the evaluation of patients with increased mast cells and peripheral eosinophilia.

Current Treatment Options: Impact of Cytogenetics on the Course of Myelodysplasia

The heterogeneity of myelodysplastic syndromes (MDS) has driven the search for unifying biologic and clinical features that would stratify patients into distinct prognostic and therapeutic subgroups. Cytogenetics has been shown to impact the course of myelodysplasia. Despite the presence of non-random cytogenetic abnormalities in approximately 50% of MDS patients, it is significant that only a proportion of metaphases may contain the abnormality. Clonality studies however show that the karyotypically normal metaphases are still part of the MDS clone. This would suggest that the chromosomal abnormality may not be the initiating lesion in MDS, and that the gross karyotypic changes represent clonal evolution in a genetically unstable population. Yet, as will be described below, specific cytogenetic abnormalities are associated with clinically and biologically distinct forms of the disease, most notable in the response of del(5q) patients to lenalidomide. One possible explanation for the appearance of non-random mutational events could relate to the interaction of MDS cells with their microenvironment. Whatever the initiating lesion in the MDS stem cell, the end result is a clonal expansion where the marrow becomes populated by the monoclonal progeny of this cell. Interaction of these cells with a microenvironment which has been shown to be rich in pro-apoptotic cytokines such as tumor necrosis factor alpha (TNFa), leads to increased genetic instability. Hypoxia mediated decrease in DNA repair enzymes could further accelerate mutational events culminating in accumulation of multiple chromosomal abnormalities. Some of these chromosomal changes are associated with increased sensitivity to specific drugs. Lenalidomide has shown a high degree of efficacy in MDS patients with del(5q), although the target for the drug is unknown since a small but significant subset of MDS patients without del(5q) abnormality also respond to the drug. In contrast, the molecular target for imatinib mesylate is known; mutations in tyrosine kinase receptor family of genes found in patients with t(5;12) and del(4q12) make these individuals sensitive to the drug. Patients with isolated trisomy 8 have an immune component to the disease phenotype which can be targeted by cyclosporine and or anti-thymocyte globulin (ATG), especially in the presence of a PNH (paroxysmal nocturnal hemoglobinurea) clone. In the absence of these specific cytogenetic abnormalities described above, the two FDA approved hypomethylating agents 5 azacytidine and decitabine should be considered as therapeutic alternatives.

PDGFRalpha/FIP1L1-positive chronic eosinophilic leukemia presenting with retro-orbital localization: efficacy of imatinib treatment

INTRODUCTION

The fusion protein between the platelet-derived growth factor receptor alpha (PDGFRalpha, P) gene and the Fip1-like1 (FIP1L1, F) may be identified in 14 to 60% of HES and it indicates a clonal hypereosinophilic syndrome called F/P-positive CEL. We herein report a case of F/P-positive CEL with retro-orbital localization, who was successfully treated with imatinib.

CASE REPORT

A 53-year-old male presented an absolute eosinophil count of 25,000/mm(3), anemia (Hb 10.2 g/dl) and a moderate increase in the platelet count (571,000/mm(3)). A clinical examination revealed left exophthalm, associated with diffuse hypoesthesia and diplopia. A CT scan of orbits showed a lesion located in the lachrymal fossa of the left orbit with intra- and extra-conical extension. Molecular analysis excluded the presence of bcr/abl transcript while a F/P fusion tyrosine kinase signal was documented. Imatinib mesylate (IM) was started and, after 7 days of treatment eosinophil count significantly declined along with a dramatic reduction of the left exophthalm. IM dosage was increased up to 300 mg/day. The drug was well tolerated with an initial modest haematological toxicity. The left exophthalm, as well as hypoesthesia and diplopia, disappeared after IM therapy. MRI showed a clear reduction of the intra- and extra-conical growth process. BM molecular signal of the F/P fusion gene resulted undetectable after 4 weeks of treatment.

CONCLUSION

In our case, the diagnosis of FIPIL1-PDGFRA-positive CEL and IM therapy has allowed the patient to experience an excellent clinical therapeutic result, avoiding surgical treatment of the retro-orbital mass.

Molecular mechanisms underlying FIP1L1-PDGFRA-mediated myeloproliferation

An interstitial deletion on chromosome 4q12 resulting in the formation of the FIP1L1-PDGFRA fusion protein is involved in the pathogenesis of imatinib-sensitive chronic eosinophilic leukemia. The molecular mechanisms underlying the development of disease are largely undefined. Human CD34(+) hematopoietic progenitor cells were used to investigate the role of FIP1L1-PDGFRA in modulating lineage development. FIP1L1-PDGFRA induced both proliferation and differentiation of eosinophils, neutrophils, and erythrocytes in the absence of cytokines, which could be inhibited by imatinib. Whereas expression of FIP1L1-PDGFRA in hematopoietic stem cells and common myeloid progenitors induced the formation of multiple myeloid lineages, expression in granulocyte-macrophage progenitors induced only the development of eosinophils, neutrophils, and myeloblasts. Deletion of amino acids 30 to 233 in the FIP1L1 gene [FIP1L1(1-29)-PDGFRA] gave rise to an intermediate phenotype, exhibiting a dramatic reduction in the number of erythrocytes. FIP1L1-PDGFRA and FIP1L1(1-29)-PDGFRA both induced the activation of p38 and extracellular signal-regulated kinase 1/2 (ERK1/2) in myeloid progenitors, whereas signal transducers and activators of transcription 5 (STAT5) and protein kinase B/c-akt were only activated by FIP1L1-PDGFRA. Dominant-negative STAT5 partially inhibited FIP1L1-PDGFRA-induced colony formation, whereas combined inhibition of phosphatidylinositol-3-kinase and ERK1/2 significantly reversed FIP1L1-PDGFRA-induced colony formation. Taken together, these results suggest that expression of FIP1L1-PDFGRA in human hematopoietic progenitors induce a myeloproliferative phenotype via activation of multiple signaling molecules including phosphatidylinositol-3-kinase, ERK1/2, and STAT5.

Recent advances in eosinophil biology

Eosinophils are pleiotropic multi-functional leukocytes involved in initiation and propagation of diverse inflammatory responses. Recent studies examining eosinophil biology have focused on delineating the molecular basis of FIP1L1/PDGRFalpha-fusion gene induced HES, the molecular steps involved in eosinophil recruitment in tumor-associated eosinophilia and EGID, and the role of eosinophils in asthma. In this review, these studies are summarized, focusing on the implications of these findings in the understanding the role of eosinophils in diseases.

Congestive heart failure is a rare event in patients receiving imatinib therapy

A recent preclinical study suggested that imatinib may be cardiotoxic in some patients. We reviewed all reported serious adverse events of cardiac adverse events occurring in patients on clinical trials involving imatinib. Among 1276 patients enrolled, 22 (1.7%) were identified as having symptoms that could be attributed to systolic heart failure. The median age was 70 years (range, 49 to 83 years). The median time from start of imatinib therapy was 162 days (range, 2-2045 days). At the time these events were reported, 8 (0.6%) were considered possibly or probably related to imatinib. A total of 18 patients had previous medical conditions predisposing to cardiac failure: congestive heart failure (CHF; 6 [27%] patients), diabetes mellitus (6 [27%] patients), hypertension (10 [45%] patients), coronary artery disease (CAD; 8 [36%] patients), arrhythmia (3 [14%] patients), and cardiomyopathy (1 [5%] patient). Of the 22 patients, 11 continued imatinib therapy with dose adjustments and management for the CHF symptoms without further complications. Imatinib therapy as a causal factor of CHF is uncommon, mainly seen in elderly patients with preexisting cardiac conditions. Patients with previous cardiac history should be monitored closely and treated aggressively with standard medical therapy, including diuretics, if they develop symptoms suggestive of heart failure.

Unusual case of aortic valve involvement in patient with Löffler’s Endomyocarditis: management, follow-up and short review of the literature

Idiopathic hypereosinophilic syndrome (IHES) is an uncommon systemic disease which is characterised by blood eosinophilia and multiple clinical presentations. Cardiac involvement is the major cause of mortality and morbidity. Here we describe a 59-year-old man with symptoms of progressive dyspnea on exertion, and productive cough as an unusual case of Löffler endomyocarditis with a mass on the aortic valve which showed regression with treatment.