Molecular classification and pathogenesis of eosinophilic disorders: 2005 update

Infrequent Presentations of Chronic NPM1-Mutated Myeloid Neoplasms: Clinicopathological Features of Eight Cases from a Single Institution and Review of the Literature

Non-acute myeloid neoplasms (MNs) with NPM1 mutations (NPM1mut-MNs) pose a diagnostic and therapeutic dilemma, primarily manifesting as chronic myelomonocytic leukemia (CMML) and myelodysplastic syndromes (MDS). The classification and treatment approach for these conditions as acute myeloid leukemia (AML) are debated. We describe eight cases of atypical NPM1mut-MNs from our institution and review the literature. We include a rare case of concurrent prostate carcinoma and MN consistent with chronic eosinophilic leukemia, progressing to myeloid sarcoma of the skin. Of the remaining seven cases, five were CMML and two were MDS. NPM1 mutations occur in 3-5% of CMML and 1-6% of MDS, with an increased likelihood of rapid evolution to AML. Their influence on disease progression varies, and their prognostic significance in non-acute MNs is less established than in AML. Non-acute MNs with NPM1 mutations may display an aggressive clinical course, emphasizing the need for a comprehensive diagnosis integrating clinical and biological data. Tailoring patient management on an individualized basis, favoring intensive treatment aligned with AML protocols, is crucial, regardless of blast percentage. Research on the impact of NPM1 mutations in non-acute myeloid neoplasms is ongoing, requiring challenging prospective studies with substantial patient cohorts and extended follow-up periods for validation.

Rare cancers: Challenges & issues

Rare cancers account for about 22 per cent of all cancers diagnosed worldwide, disproportionately affecting some demographic groups, with an occurrence of less than 6 per 100,000 individuals annually. Many rare cancers in adults, adolescents and children are not curable, and patients and care providers have little option to take therapeutic decisions. The epidemiology of rare cancers is a challenging area of study but is inadequately addressed. Despite efforts mainly in some European nations, a few improvements have been observed in the management of rare cancers. Reasons for this obvious stagnation are multifactorial and are mainly inherent to logistical difficulties in carrying out clinical trials in very small patient populations, hesitation of the pharmaceutical industry to spend in small markets and complexity in creating adequate information for the development of cost-effective drugs. Rare cancers also face specific challenges that include late and incorrect diagnosis, lack of clinical expertise and lack of research interest and development of new therapies. The utilization of nationally representative study findings for the patients' evaluation may possibly offer chances to find out pathogenesis and prevalence, and this will eventually lead to control and prevention. Currently, advancing targeted therapies offer a great opportunity for the better management of rare cancers. Conducting clinical trials with small patient population, innovative clinical trial approach, prevailing controlling obstacles for international cooperation and financial support for research are the present challenges for rare cancers. The International Rare Cancers Initiative functions as a main platform for achieving new international clinical trials in rare tumours. This review delineates the current challenges and issues in the interpretation, management and research scenarios of rare cancers.

Polyps, grommets and eosinophilic granulomatosis with polyangiitis

OBJECTIVE

To explore the link between nasal polyposis, refractory otitis media with effusion and eosinophilic granulomatosis with polyangiitis.

METHODS

A retrospective observational study was carried out of patients diagnosed with refractory otitis media with effusion necessitating grommet insertion and who had nasal polyps. Patients were evaluated to determine if they fulfilled the diagnostic criteria of eosinophilic granulomatosis with polyangiitis.

RESULTS

Sixteen patients (10 males and 6 females) were identified. The mean age of grommet insertion was 45.4 years. The mean number of grommets inserted per patient was 1.6. The mean number of nasal polypectomies was 1.7. All 16 patients had paranasal sinus abnormalities and otitis media with effusion, 14 had asthma, 9 had serological eosinophilia and 7 had extravascular eosinophilia. Nine patients met the diagnostic criteria for eosinophilic granulomatosis with polyangiitis.

CONCLUSION

The co-presence of nasal polyps and resistant otitis media with effusion should raise the possibility of eosinophilic granulomatosis with polyangiitis.

Therapeutic effect of anti-IL-5 on eosinophilic myocarditis with large pericardial effusion

Eosinophilic myocarditis (EM) is a rare myocardial disease that results from various eosinophilic diseases, such as idiopathic hypereosinophilic syndrome, helminth infection, medications and vasculitis. Patients with EM may present with different severities, ranging from mild symptoms to a life-threatening condition. Diagnosis of EM is a challenge and requires an extensive workup, including endomyocardial biopsy. Treatment options are limited because EM is rare and there is a lack of randomised controlled trials. We report a case of EM that presented as cardiac tamponade, which was initially treated with high-dose prednisone and immunosuppressant medications without significant improvement. Mepolizumab (anti-interleukin (IL)-5 antibody) was then applied, leading to an increased ejection fraction and stabilised cardiac function. This case report shows, for the first time, that mepolizumab has novel effects in treating EM. Our findings suggest that mepolizumab can be used as a steroid-sparing agent for treating EM.

Current Diagnostic and Therapeutic Aspects of Eosinophilic Myocarditis

Eosinophilic myocarditis (EM) represents a rare form of myocardial inflammation with very heterogeneous aetiology. In developed countries, the most prevalent causes of EM are hypersensitivity or allergic reactions, as well as hematological diseases leading to eosinophilia. The disease may have a variable clinical presentation, ranging from asymptomatic forms to life-threatening conditions. Most patients with EM have marked eosinophilia in peripheral blood. Endomyocardial biopsy needs to be performed in most cases in order to establish a definitive diagnosis of EM. The therapy depends on the underlying aetiology. Immunosuppressive therapy represents the treatment mainstay in the majority of EM forms.

The effects of phototherapy on eosinophil and eosinophilic cationic protein in newborns with hyperbilirubinemia

Newborns with jaundice requiring or not requiring phototherapy (PT) are at greater risk of developing asthma later in life. In this study, we investigated the effect of PT treatment on eosinophil and eosinophilic cationic protein (ECP) levels in newborns with severe hyperbilirubinemia. Thirty newborns diagnosed with severe hyperbilirubinemia and exposed to light-emitting diode (LED) PT were enrolled into the study. Total serum bilirubin (TSB) levels, complete blood count and serum ECP concentrations were measured before and after PT. TSB and hemoglobin (Hb) counts were lower after PT (p = 0.001). There was no difference between leukocyte, lymphocyte, neutrophil and platelet count before and after PT. Eosinophil levels were increased after PT, although not significantly. ECP levels were higher after PT (p = 0.006). It may be speculated that newborns treated with LED PT, increased ECP might play a role in developing allergic diseases later in life.

Discovery of imatinib-responsive FIP1L1-PDGFRA mutation during refractory acute myeloid leukemia transformation of chronic myelomonocytic leukemia

The FIP1L1-PDGFRA rearrangement results in constitutive activation of the tyrosine kinase PDGFRA. Neoplasms harboring this rearrangement are responsive to imatinib mesylate at doses much lower than those recommended for the treatment of chronic myelogenous leukemia. Only a single report has described the identification of FIP1L1-PDGFRA in chronic myelomonocytic leukemia (CMML). Herein, we present a case report of a patient in whom the FIP1L1-PDGFRA was discovered as he evolved from CMML to acute myeloid leukemia (AML). The presence of a dominant neoplastic clone with FIP1L1-PDGFRA rearrangement was suspected on the basis of sudden onset of peripheral and bone marrow eosinophilia and confirmed by fluorescence in situ hybridization and molecular diagnostic tests. Whereas the patient was initially refractory to chemotherapy before the rearrangement was detected, subsequent therapy with imatinib led to complete remission.

Identification of Ponatinib as a potent inhibitor of growth, migration, and activation of neoplastic eosinophils carrying FIP1L1-PDGFRA

In chronic eosinophilic leukemia, the transforming oncoprotein FIP1L1-PDGFRA is a major target of therapy. In most patients, the tyrosine kinase inhibitor (TKI) imatinib induces complete remission. For patients who are intolerant or resistant, novel TKIs have been proposed. We examined the in vitro effects of 14 kinase blockers on growth and function of EOL-1 cells, a FIP1L1-PDGFRA(+) eosinophil cell line. Major growth-inhibitory effects were seen with all PDGFR-blocking agents, with IC50 values in the low nanomolar range: ponatinib, 0.1-0.2 nmol/L; sorafenib, 0.1-0.2 nmol/L; masitinib, 0.2-0.5 nmol/L; nilotinib, 0.2-1.0 nmol/L; dasatinib, 0.5-2.0 nmol/L; sunitinib, 1-2 nmol/L; midostaurin, 5-10 nmol/L. These drugs were also found to block activation of PDGFR-downstream signaling molecules, including Akt, S6, and STAT5 in EOL-1 cells. All effective TKIs produced apoptosis in EOL-1 cells as determined by microscopy, Annexin-V/PI, and caspase-3 staining. In addition, PDGFR-targeting TKIs were found to inhibit cytokine-induced migration of EOL-1 cells. In all bioassays used, ponatinib was found to be the most potent compound in EOL-1 cells. In addition, ponatinib was found to downregulate expression of the activation-linked surface antigen CD63 on EOL-1 cells and to suppress the growth of primary neoplastic eosinophils. We also examined drug effects on Ba/F3 cells expressing two clinically relevant, imatinib-resistant, mutant forms of FIP1L1-PDGFRA, namely T674I and D842V. Strong inhibitory effects on both mutants were seen only with ponatinib. In summary, novel PDGFR-targeting TKIs may be alternative agents for the treatment of patients with imatinib-resistant chronic eosinophilic leukemia. Although several different PDGFR-targeting agents are effective, the most potent drug appears to be ponatinib.

Biochemical and haematological changes in HIV subjects receiving winniecure antiretroviral drug in Nigeria

BACKGROUND

Hematological and biochemical abnormalities are among the most common clinicopathological manifestations of HIV patients on ART. Consequently, the development and assessment of indigenous antiretroviral drugs with minimal abnormalities becomes a necessity. The objective of this investigation was to assess potential haematological and biochemical abnormalities that may be associated with the administration of Winniecure ART in HIV patients undergoing treatment in Nigeria. Fifty (50) confirmed HIV positive ART naïve patients aged 36 ± 10 were observed for haematological and biochemical responses for 12 weeks. Haematological responses were assessed thrice at 6 weeks interval using coulter Ac-T differential analyser and biochemical indicators (bilirubin, creatine, urea, amylase, ALT, ALP, AST, albumin) assayed spectrophotometrically.

RESULTS

The biochemical parameters ALP (P < 0.05), ALT (P < 0.0001), AST (P < 0.001) and amylase (P < 0.05) slightly increased at the 12th week, no significant change was observed in plasma creatinine and urea concentrations while albumin levels decreased non-significantly (P > 0.002). Haematological results showed consistent reduction of ESR, eosinophil, absolute and differential lymphocytes, granulocytes and total WBC in the test subjects throughout the assessment period. Conversely, haemoglobin, platelet and PCV increased significantly (P < 0.05). At the 12th week thrombocytopenia (10.30%) and anaemia (76%) were reduced to 2% and 31% respectively while neutropenia (4.2 to 8%), leucopenia (26.8 to 30%) and lymphopenia (1 to 10%) increased. No cases of neutrophilia, lymphocytosis, eosinophilia and leukocytosis was observed.

CONCLUSION

The drug has a reduced haematological abnormalities and normal kidney function was unaffected though there were signs of possible abnormal levels of hepatic enzymes beyond 12 weeks of treatment.

Contemporary consensus proposal on criteria and classification of eosinophilic disorders and related syndromes

Eosinophilia is an important indicator of various neoplastic and nonneoplastic conditions. Depending on the underlying disease and mechanisms, eosinophil infiltration can lead to organ dysfunction, clinical symptoms, or both. During the past 2 decades, several different classifications of eosinophilic disorders and related syndromes have been proposed in various fields of medicine. Although criteria and definitions are, in part, overlapping, no global consensus has been presented to date. The Year 2011 Working Conference on Eosinophil Disorders and Syndromes was organized to update and refine the criteria and definitions for eosinophilic disorders and to merge prior classifications in a contemporary multidisciplinary schema. A panel of experts from the fields of immunology, allergy, hematology, and pathology contributed to this project. The expert group agreed on unifying terminologies and criteria and a classification that delineates various forms of hypereosinophilia, including primary and secondary variants based on specific hematologic and immunologic conditions, and various forms of the hypereosinophilic syndrome. For patients in whom no underlying disease or hypereosinophilic syndrome is found, the term hypereosinophilia of undetermined significance is introduced. The proposed novel criteria, definitions, and terminologies should assist in daily practice, as well as in the preparation and conduct of clinical trials.

Multi-system mitochondrial disorder with recurrent steroid-responsive eosinophilia

Though mitochondrial disorders due to a respiratory chain defect may manifest with haematological abnormalities such as anaemia, neutropenia, or thrombocytopenia, recurrent steroid-responsive eosinophilia has not been reported as a manifestation of a mitochondrial disorder. In a polymorbid 65-year old female recurrent erythema, asthma, chronic bronchitis, gastritis with eosinophilic granuloma, recurrent episodes of hypereosinophilia, and polyarthralgia suggested Churg–Strauss syndrome, which was excluded upon absence of eosinophilic vasculitis on any of the biopsies. However, corticosteroids were effective for hypereosinophilia. In addition to the hypereosinophilic syndrome a mitochondrial disorder with multi-system affection was diagnosed upon the clinical presentation and a muscle biopsy indicative of a mitochondrial disorder. Hypereosinophilia was interpreted as a manifestation of the mitochondrial disorder after exclusion of various differentials. Mitochondrial disease may go along with marked eosinophilia mimicking Churg–Strauss syndrome. Steroids may be useful to resolve episodic eosinophilia but may be ineffective for other features of mitochondrial disorders.

BCR-ABL-negative chronic myeloid leukemia

Constitutive activation of protein tyrosine kinases plays a central role in the pathogenesis of myeloproliferative disorders, including BCR-ABL-negative chronic myeloid leukemia. Current research is focused on elucidating the full spectrum of causative mutations in this rare, heterogeneous disease. Activated tyrosine kinases are excellent targets for signal transduction therapy, and an accurate diagnosis including morphology, karyotyping, and molecular genetics will become increasingly important to direct individualized treatment. In addition, new molecular findings need to be incorporated into disease classification systems.

[Incidence and causes of hypereosinophilia (corrected) in the patients of a university hospital]

BACKGROUND

Eosinophilia may be associated with various primary and reactive conditions. The incidence and the causes of eosinophilia might have been changed according to the changes in the incidence of diseases such as cancer, chronic degenerative diseases, etc. We have conducted a retrospective study to investigate the incidence and causes of eosinophilia.

METHODS

Eosinophilia and hypereosinophilia were defined when absolute eosinophil count was greater than 500/microL and 1,500/microL, respectively. Patient's clinical records were reviewed to find out the underlying clinical conditions responsible for causes of hypereosinophilia. Conventional chromosomal analysis, reverse transcriptase PCR and FISH for gene rearrangement were performed to check the presence of clonal eosinophilia.

RESULTS

Out of 41,137 patients who had a hematology profile performed, 5,019 (12.2%) and 373 patients (0.9%) were found to have eosinophilia and hypereosinophilia, respectively. Among patients with hypereosinophilia, 227 patients (60.9%) had identifiable and/or possible causes. The major causes of hypereosinophilia were malignancy (35.2%), allergy and skin diseases (18.1%), infectious diseases (15.4%), hepatobiliary diseases (7.5%), bone marrow clonal diseases (6.6%) and parasite infections (6.6%). We also found a rare case of FIP1L1-PDGFRalpha positive chronic eosinophilic leukemia combined with light chain multiple myeloma.

CONCLUSIONS

We found a difference in the distribution of causes of hypereosinophilia in comparison with previous Korean studies, and the most common cause of hypereosinophilia in the current study was malignancy. A rare case of clonal eosinophilia (chronic eosinophilic leukemia) associated with multiple myeloma was confirmed using molecular studies.

Case 32. Eosinophilia: Reactive or neoplastic?

A diagnosis of eosinophilic leukemia was suspected in a patient who presented with eosinophilia and a mild macrocytic anemia and was found to have trisomy 8. Further tests and the subsequent clinical course permitted an accurate diagnosis.

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.

8p11 myeloproliferative syndrome preceded by t(8;9)(p11;q33), CEP110/FGFR1 fusion transcript: morphologic, molecular, and cytogenetic characterization of myeloid neoplasms associated with eosinophilia and FGFR1 abnormality

We report a rare case of t(8;9)(p11;q33) in a patient with 8p11 myeloproliferative syndrome (EMS) that was preceded by centrosomal protein 110kDa (CEP110; previously CEP1)/fibroblast growth factor receptor 1 (FGFR1) fusion transcript. A 36-year-old man was brought to Severance Hospital with a nasopharyngeal mass and eosinophilia. Biopsy of the left tonsil and nasopharynx revealed diffuse infiltration of atypical lymphoid cells, and he was diagnosed with precursor T-cell lymphoma with hypereosinophilic syndrome. Two months later, chromosome study revealed a 46,XY,t(8;9)(p11;q33) karyotype, and the CEP110/FGFR1 fusion transcript was detected by reverse transcription-polymerase chain reaction (RT-PCR) in both this and the previous bone marrow specimen. Timely molecular and cytogenetic tests are of value for diagnosis and treatment of the newly classified "myeloid neoplasms associated with clonal eosinophilic disorders" (according to 2008 World Health Organization criteria).

Oral mucosa lesions in hypereosinophilic syndrome--an update

Hypereosinophilic syndrome (HES) is a rare disorder characterized by persistent and marked eosinophilia. Some HES forms have a poor prognosis, either because of end-organ damage (particularly endomyocardial fibrosis), or because of associated myeloid leukemia or malignant T-cell lymphoma. Oral mucosa ulcerations can be early clinical signs in severe forms. They are discrete, round or oval, sometimes confluent ulcers or erosions, located on non-keratinized, unattached oral mucosa. In the last 15 years a better understanding of eosinophil biology has led to a new clinical classification of HES. The lymphocytic form is characterized by T-lymphocyte clonality, IL-5 production, and a possible progression to T-cell lymphoma. Oral lesions are more frequently associated with the myeloproliferative form, characterized by an increased risk of developing myeloid malignancies and a good response to a recent anti-tyrosine kinase therapy (imatinib mesylate). The target of imatinib is a novel kinase resulting from an 800-kb deletion on chromosome 4. Recently, the resulting FIP1L1-PDGFRalpha fusion gene was characterized as a marker of response to imatinib. Exclusion of other erosive ulcerative oral disease and early recognition of HES in patients with oral ulcerations, and precise characterization of the lymphocytic or myeloproliferative form are therefore important to rapidly initiate an effective therapy.

Synchronous FIP1L1-PDGFRA-positive chronic eosinophilic leukemia and T-cell lymphoblastic lymphoma: a bilineal clonal malignancy

Several reports of successful empirical treatment of idiopathic hypereosinophilic syndrome with imatinib led to the recent identification of the FIP1L1-PDGFRA fusion gene rearrangement, which characterizes a distinctive group of chronic eosinophilic leukemias. This fusion gene can be detected in eosinophils, neutrophils, mast cells, T cells, B cells and monocytes in FIP1L1-PDGFRA-positive hypereosinophilic patients suggesting a multilineage involvement. Furthermore, the same FIP1L1-PDGFRA rearrangement was identified in patients with hypereosinophilia and atypical mast cell proliferations, raising the question of a disease with two concomitant lines of differentiation. In addition, a recent report noted two cases with the association of FIP1L1-PDGFRA-positive chronic eosinophilic leukemia and T-cell lymphoblastic lymphoma (T-LBL). We report here the only third case of synchronous chronic eosinophilic leukemia and T-LBL, both associated with a FIP1L1-PDGFRA fusion transcript, confirming the occurrence of such disease and suggesting a clonal proliferation with two lines of differentiation probably arising from a primitive multipotent medullary stem cell.

Imatinib mesylate in the treatment of hematologic malignancies

The treatment of hematologic malignancies has been based for many years on chemotherapy and possibly, for the more aggressive forms, stem cell transplantation. In 2001, the signal transduction inhibitor 571 (STI571, imatinib mesylate) was reported to have striking effects in chronic myeloid leukaemia patients. Since then, imatinib became the first molecular-targeted agent approved for the treatment of human cancer and was later on demonstrated to be effective in other malignancies, such as Philadelphia positive acute lymphoid leukemia, hypereosinophilic syndromes, gastrointestinal stromal tumours and more recently, systemic mastocytosis and other myeloprolipherative disease-carrying platelet-derived growth factor receptor abnormalities. In this article, the authors review the evidence which led to imatinib approval in the treatment of several of the above mentioned diseases.

Fatal Loeffler's endocarditis due to hypereosinophilic syndrome

Hypereosinophilic syndrome (HES) is a rare disorder that can manifest in various organ systems. We report the case of a 54-year-old woman with a remote history of seizure disorder who presented with early signs of right-sided heart failure. Laboratory studies showed significant eosinophilia (8 x 10(9) l(-1)). Computed tomography showed heterogeneity of the liver, mild ascites, moderate pleural effusion, multiple small pulmonary emboli, and a large right ventricular mass. Cardiac magnetic resonance imaging demonstrated that the right ventricular mass was due to thrombus and extensive endomyocardial fibrosis, consistent with Loeffler's endocarditis. Bone marrow biopsy showed marked eosinophilia but no abnormal myeloid maturation or a lymphoproliferative disorder; flow cytometry showed no clonality. Extensive infectious, immunologic, and toxicological studies were negative. Despite resolution of peripheral eosinophilia with medical management, including corticosteroids and cytotoxic agents, anticoagulation for pulmonary emboli and ventricular thrombus, and conventional treatment for heart failure, she developed worsening anasarca and died from ventricular fibrillation within 4 weeks of presentation. Autopsy confirmed the diagnosis. Loeffler's endocarditis, usually a late manifestation of HES, is characterized by fibrous thickening of the endocardium, leading to apical obliteration and restrictive cardiomyopathy, resulting in heart failure, thromboembolic events, or atrial fibrillation. HES is a potentially fatal disease with less than 50% reported 10-year survival. This case presentation is unusual in its rapidly progressive course leading to sudden death.

The Gain-of-Function JAK2 V617F Mutation Shifts the Phenotype of Essential Thrombocythemia and Chronic Idiopathic Myelofibrosis to More "Erythremic" and Less "Thrombocythemic": A Molecular, Histologic, and Clinical Study

We investigated the prevalence of the JAK2 V617F gain-of-function mutation in patients with Philadelphia chromosome-negative chronic myeloproliferative disorders (Ph- MPD) and explored the links between JAK2 mutational status and the clinicopathologic picture of essential thrombocythemia (ET), chronic idiopathic myelofibrosis (CIMF), and polycythemia vera (PV). Allele-specific polymerase chain reaction results for 59 ET, 18 CIMF, and 9 PV cases were compared with values for clinical variables at presentation and last follow-up and with the diagnostic trephine bone marrow biopsy pictures. JAK2 V617F was found in 38 (64%) of ET cases, 7 (39%) of CIMF cases, and 9 (100%) of PV cases. The ET patients with the mutant JAK2 showed significantly higher (although not overtly polycythemic) red blood cell parameter values, lower platelet counts, and higher white blood cell counts. Similar trends were found in CIMF. Megakaryocyte clustering was much less pronounced in the CIMF cases with mutant JAK2, with an analogous trend occurring in the ET cases. Bone marrow cellularity values and the numbers of CD34+ and CD117+ blasts in the ET and CIMF groups did not differ. Fibrosis was slightly less marked in the ET cases with mutant JAK2. The mutation did not significantly influence the clinical course during the follow-up in either disease in the short term (median follow-up, 22 months). The JAK2 V617F mutation is prevalent in all Ph- MPD and may skew their presenting phenotype, including bone marrow histology, toward a more "erythremic" and less "thrombocythemic" phenotype.

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.

The novel tyrosine kinase inhibitor EXEL-0862 induces apoptosis in human FIP1L1-PDGFR-α-expressing cells through caspase-3-mediated cleavage of Mcl-1

The FIP1-like-1 (FIP1L1)-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFR-alpha) fusion kinase causes hypereosinophilic syndrome (HES) in a defined subset of patients. Imatinib mesylate is a potent inhibitor of ABL but also of PDGFR-alpha, and has been associated with durable hematologic responses in patients with HES. However, development of mutations in the tyrosine kinase domain may hamper the activity of tyrosine kinase inhibitors (TKIs), which suggests that novel agents are warranted to prevent or overcome resistance. We evaluated the efficacy of the novel TKI EXEL-0862 in FIP1L1-PDGFR-alpha-expressing cell lines and in cells from a patient with HES harboring the FIP1L1-PDGFR-alpha gene. EXEL-0862 inhibited the proliferation of EOL-1 and imatinib-resistant T674I FIP1L1-PDGFR-alpha-expressing cells and resulted in potent inhibition of the phosphorylation of PDGFR-alpha and downstream proteins STAT3 and Erk1/2, both in vitro and ex vivo. Moreover, EXEL-0862 induced apoptotic death in EOL-1 cells and imatinib-resistant T674I FIP1L1-PDGFR-alpha-expressing cells, and resulted in significant downregulation of the antiapoptotic protein Mcl-1 through a caspase-dependent mechanism. Our data establish EXEL-0862 as a solid candidate for the targeted treatment of patients with FIP1L1-PDGFR-alpha-positive HES.

Eosinophilia in systemic mastocytosis: clinical and molecular correlates and prognostic significance

BACKGROUND

In a group of patients with systemic mastocytosis (SM), marked and sustained eosinophilia is detectable (SM-eo).

OBJECTIVE

Although the molecular defect has been defined in some cases, little is known about the impact and clinical correlates of eosinophilia.

METHODS

In a cohort of 63 patients with SM, we identified 9 with permanent eosinophilia (>1500/microL). According to the World Health Organization classification, 2 had indolent SM, 1 had smoldering SM, 2 had SM with associated chronic eosinophilic leukemia (SM-CEL), and 4 had aggressive SM.

RESULTS

SM-eo was found to be associated with a significantly reduced probability of overall and event-free survival compared with SM without eosinophilia (P < .05). In the 2 patients with SM-CEL, a CHIC2 deletion was found. By contrast, no KIT mutation at codon 816 was detectable in these patients. In the other patients with SM-eo, KIT D816V was demonstrable. The 2 patients with SM-CEL had cardiomyopathy, whereas other organ systems remained largely unaffected. By contrast, in all other patients with SM-eo, organopathy, if recorded, affected the bone marrow, liver, or/and skeletal system, but not the heart, even when eosinophilia persisted for many years.

CONCLUSIONS

The biochemical basis of eosinophilia in SM is variable and predictive for the type of organopathy.

CLINICAL IMPLICATIONS

In SM eosinophilia is of prognostic significance but is not a final diagnosis and is not invariably associated with cardiomyopathy. The latter might be restricted to cases with an associated primary eosinophilic disorder (SM-CEL).

A critical appraisal of conventional and investigational drug therapy in patients with hypereosinophilic syndrome and clonal eosinophilia

Hypereosinophilic syndrome (HES) is a rare disorder characterized by persistent and marked eosinophilia, leading to end-organ damage. Over the last decade, great progress has been made in unraveling the molecular basis of HES that has resulted in the characterization of specific genetic alterations linked to clonal eosinophilia. The most frequently encountered genetic aberrancy is the cryptic FIP1-like 1/platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA) fusion transcript, which results in an eosinophilic, myeloproliferative disorder. In addition, in a subset of patients with HES, a population of aberrant T cells that secretes interleukin-5 can be identified, indicating the existence of lymphocyte-mediated hypereosinophilia. These new insights have led to both a genetically based (re)classification of eosinophilic blood disorders and to effective therapies with targeted agents, such as small-molecule tyrosine kinase inhibitors (eg, imatinib, nilotinib, PKC412) and, more recently, monoclonal antibodies (eg, mepolizumab, alemtuzumab). These targeted therapies hold great promise for improving the clinical outcomes of patients with HES and clonal eosinophilia, and they have exhibited relatively safe toxicity profiles.

Molecular diagnosis of mast cell disorders: a paper from the 2005 William Beaumont Hospital Symposium on Molecular Pathology

Mastocytosis is a disease characterized by pathological mast cell accumulation and activation in tissues. Most patients with mastocytosis exhibit the D816V point mutation in the tyrosine kinase domain of the transmembrane receptor protein Kit, leading to its constitutive activation in bone marrow or lesional skin tissue. Detection of a codon 816 c-kit mutation is included as a minor diagnostic criterion in the World Health Organization's diagnostic criteria for systemic mastocytosis. Determining mutational status of the c-kit gene also has pharmacogenomic implications in patients considered for investigational mast cell cytoreductive therapies. This article reviews diagnostic and therapeutic implications of c-kit mutations as well as other less common molecular abnormalities observed in mast cell disease.

Eosinophilic disorders: molecular pathogenesis, new classification, and modern therapy

Before the 1990s, lack of evidence for a reactive cause of hypereosinophilia or chronic eosinophilic leukemia (e.g. presence of a clonal cytogenetic abnormality or increased blood or bone marrow blasts) resulted in diagnosticians characterizing such nebulous cases as 'idiopathic hypereosinophilic syndrome (HES)'. However, over the last decade, significant advances in our understanding of the molecular pathophysiology of eosinophilic disorders have shifted an increasing proportion of cases from this idiopathic HES 'pool' to genetically defined eosinophilic diseases with recurrent molecular abnormalities. The majority of these genetic lesions result in constitutively activated fusion tyrosine kinases, the phenotypic consequence of which is an eosinophilia-associated myeloid disorder. Most notable among these is the recent discovery of the cryptic FIP1L1-PDGFRA gene fusion in karyotypically normal patients with systemic mast cell disease with eosinophilia or idiopathic HES, redefining these diseases as clonal eosinophilias. Rearrangements involving PDGFRA and PDGFRB in eosinophilic chronic myeloproliferative disorders, and of fibroblast growth factor receptor 1 (FGFR1) in the 8p11 stem cell myeloproliferative syndrome constitute additional examples of specific genetic alterations linked to clonal eosinophilia. The identification of populations of aberrant T-lymphocytes secreting eosinophilopoietic cytokines such as interleukin-5 establish a pathophysiologic basis for cases of lymphocyte-mediated hypereosinophilia. This recent revival in understanding the biologic basis of eosinophilic disorders has permitted more genetic specificity in the classification of these diseases, and has translated into successful therapeutic approaches with targeted agents such as imatinib mesylate and recombinant anti-IL-5 antibody.

Identification of a novel imatinib responsive KIF5B-PDGFRA fusion gene following screening for PDGFRA overexpression in patients with hypereosinophilia

Idiopathic hypereosinophilic syndrome (IHES) is a disease that is difficult to classify, and diagnosis is one of exclusion. The identification of a cytogenetically invisible interstitial deletion resulting in the fusion of FIP1-Like-1 (FIP1L1) to platelet-derived growth factor receptor alpha (PDGFRA) has enabled many IHES cases to be reclassified as chronic eosinophilic leukemia. As it is likely that PDGFRA may fuse to other partner genes, we established a reverse transcriptase-PCR test to detect specific overexpression of the PDGFRA kinase domain as an indicator of the presence of a fusion gene. Overexpression was detected in 12/12 FIP1L1-PDGFRA-positive patients, plus 9/217 (4%) patients with hypereosinophilia who had tested negative for FIP1L1-PDGFRA. One of the positive cases was investigated in detail and found to have a complex karyotype involving chromosomes 3, 4 and 10. Amplification of the genomic breakpoint by bubble PCR revealed a novel fusion between KIF5B at 10p11 and PDGFRA at 4q12. Imatinib, a known inhibitor of PDGFRalpha, produced a complete cytogenetic response and disappearance of the KIF5B-PDGFRA fusion by PCR, from both genomic DNA and mRNA. This study demonstrates the utility of screening for PDGFRA kinase domain overexpression in patients with IHES and has identified a third PDGFRA fusion partner in chronic myeloproliferative disorders.

Systemic mastocytosis (SM) associated with chronic eosinophilic leukemia (SM-CEL): Detection of FIP1L1/PDGFRα, classification by WHO criteria, and response to therapy with imatinib

Based on generally accepted criteria and the WHO-classification, a subset of patients with systemic mastocytosis (SM) have (or develop) an associated clonal hematologic non-mast cell lineage disease (SM-AHNMD). We describe a case of SM with coexisting chronic eosinophilic leukemia (SM-CEL). The patient, a 51-year-old male, was first seen in 1992 with small-sized infiltrates of spindle-shaped mast cells in his marrow, and marked eosinophilia. Retrospectively, a CHIC2 deletion and the FIP1L1/PDGFRalpha fusion gene-product were demonstrable by FISH analysis and RT-PCR, respectively. SM-associated organopathy or mediator-related symptoms were not recorded. However, the patient developed cardiomyopathy. Therapy with interferon-alpha, hydroxyurea, and corticosteroids were without effects. By contrast, therapy with imatinib was followed by a fast and sustained response with complete and stable regression of eosinophilia, drop in eosinophil cationic protein, and decrease of serum tryptase to normal levels. This case provides further evidence for the potential of co-existence of SM with a primary eosinophilic disorder (CEL) defined by the FIP1L1/PDGFRalpha fusion gene. Because of the availability of a superior targeted drug (imatinib), it is of importance to screen for FIP1L1/PDGFRalpha in suspected CEL with or without co-existing SM.

Churg-Strauss syndrome in children: a clinical and pathologic review

Churg-Strauss syndrome is a vasculitis accompanied by asthma and eosinophilia. It is generally considered a disease of adults; occurrence in children has been reported infrequently. Here we report 2 pediatric patients with Churg-Strauss syndrome manifesting with prominent pulmonary involvement. One, a 16-year-old with a previous history of asthma, presented with pleuritic chest pain and a peripheral pulmonary nodule complicated by an eosinophilic pleural effusion. The other patient presented at age 6 with cough, weight loss, and radiographic infiltrates. Lung biopsies revealed elements characteristic of Churg-Strauss syndrome, including eosinophilic microabscesses and vasculitis. Three- and 5-year follow-up showed continued symptoms in both patients despite medical therapy. Both patients illustrate many of the typical features of Churg-Strauss syndrome. We report these cases to expand the scant knowledge about Churg-Strauss syndrome in pediatric patients and to heighten awareness that this serious disease may affect the pediatric population. The relevant literature on Churg-Strauss syndrome, with specific reference to childhood cases, is reviewed.

Bullous pemphigoid associated with hypereosinophilic syndrome: simultaneous response to imatinib

Hypereosinophilic syndrome is a myeloproliferative disorder defined by unexplained, persistent hypereosinophilia with cutaneous or systemic involvement. We describe a patient with coexistence of hypereosinophilic syndrome and bullous pemphigoid. Treatment with the novel tyrosine kinase inhibitor imatinib mesylate resulted in durable remission of hypereosinophilia and skin lesions.

FIP1L1-PDGFRA in eosinophilic disorders: Prevalence in routine clinical practice, long-term experience with imatinib therapy, and a critical review of the literature

We previously studied clinico-pathologic features of 89 consecutive adult patients with moderate-to-severe eosinophilia, and reported a FIP1L1-PDGFRA prevalence of 12%. In that series, all 11 FIP1L1-PDGFRA+ patients receiving imatinib achieved a complete response. We now extend our observations through a study of 741 unselected patients with eosinophilia for FIP1L1-PDGFRA, and present longer term follow up data for the imatinib-treated cohort. We also include data for three previously unreported FIP1L1-PDGFRA+ patients. Among the 741 requests, only 21 (3%) were found to carry the FIP1L1-PDGFRA mutation. While all 14 FIP1L1-PDGFRA+ patients receiving imatinib achieved a complete response, the 4 patients who attempted to discontinue imatinib all relapsed. We also find that it is possible to maintain patients in clinical remission with an empirically derived schedule of low-dose (50-100 mg), intermittent (once daily to once weekly) imatinib. Lastly, we present a comprehensive review of the literature pertaining to FIP1L1-PDGFRA in order to address several key aspects of this mutation from a clinical standpoint.

Eosinophilia: secondary, clonal and idiopathic

Blood eosinophilia signifies either a cytokine-mediated reactive phenomenon (secondary) or an integral phenotype of an underlying haematological neoplasm (primary). Secondary eosinophilia is usually associated with parasitosis in Third World countries and allergic conditions in the West. Primary eosinophilia is operationally classified as being clonal or idiopathic, depending on the respective presence or absence of a molecular, cytogenetic or histological evidence for a myeloid malignancy. The current communication features a comprehensive clinical summary of both secondary and primary eosinophilic disorders with emphasis on recent developments in molecular pathogenesis and treatment.

Eosinophilia, myositis, and myasthenia gravis associated with a thymoma

Hypereosinophilia has been associated with a wide variety of systemic disorders, including myositis. Myositis develops in a minority of patients with myasthenia gravis associated with a thymoma. We present a patient who developed a life-threatening myopathy in which testing demonstrated the concurrence of hypereosinophilia, myositis, and myasthenia gravis associated with thymoma. Thymoma-associated T-cell abnormalities may well have contributed to this rare association. This case underscores the need to reevaluate constantly the presumed cause of clinical complaints, as more than one cause may be present.