Targeted treatment of hypereosinophilic syndromes and chronic eosinophilic leukemias with imatinib mesylate

Cytogenetic and molecular aspects of Philadelphia negative chronic myeloproliferative disorders: clinical implications

Chronic myeloproliferative disorders (CMPD) are clonal disorders of the hematopoietic stem cell. The myeloid lineage shows increased proliferation with effective maturation, while peripheral leukocytosis, thrombocytosis or elevated red blood cell mass are found. In Philadelphia negative CMPD recurrent cytogenetic abnormalities occur, but no specific abnormality has been defined to date. The spectrum of cytogenetic aberrations is heterogeneous ranging from numerical gains and losses to structural changes including unbalanced translocations. The most common chromosomal abnormalities are 20q-, 13q-, 12p-, +8, +9, partial duplication of 1q, balanced translocations involving 8p11 and gains in 9p. Cytogenetic analysis of CMPD by conventional or molecular techniques has an important role in establishing the diagnosis of a malignant disease, adding also more information for disease outcome. Molecular studies may detect the possible role of candidate genes implicated in the neoplastic process, addressing new molecular target therapies. FIP1L1/PDGFRalpha rearrangements, as well as alterations of PDGFRbeta or FGFR1 gene have been found to be associated with specific types of CMPD. Recently, a novel somatic mutation, JAK2V617F, has been reported in most of the polycthemia vera (PV) patients, as well as in a lower percentage in essential thrombocythemia (ET) or idiopathic myelofibrosis (IMF) patients. This finding represents the most important advance in understanding of the molecular mechanisms underlined the pathogenesis of CMPD, contributing to the classification and management of patients.

Inhibition of SCF attenuates peribronchial remodeling in chronic cockroach allergen-induced asthma

The progression and severity of chronic asthma likely depends upon the intensity of the damage and remodeling of the tissue. We have developed a chronic model of allergic asthma using multiple cockroach allergen challenges. Using this clinically relevant allergen we have established significant peribronchial fibrosis and mucus overproduction. These remodeling events are accompanied by intense peribronchial inflammation, including lymphocytes and eosinophils. A cytokine that has been identified as having a prominent role in short-term allergic events, stem cell factor (SCF), appears to have a significant role in this late-stage process. Using our polyclonal antibody specific for SCF administered into the airways of mice during the final allergen challenges, we find a significant effect on the chronic peribronchial allergen-induced fibrotic remodeling. This was characterized by reduced inflammation, especially eosinophils, as well as reduced hydroxyproline levels in anti-SCF compared to control antibody-treated animals. In addition, when we examined chemokines associated with the chronic disease and neutralized SCF in vivo we observed a corresponding decrease in CCL6 and CCL17. Using an inhibitor, imatinib mesylate, that blocks SCF/c-kit-associated RTK, we find similar results as with anti-SCF for attenuating AHR and fibrotic changes, suggesting that a potential clinical treatment for chronic asthma already exists related to this pathway. These results further support the potential use of SCF/c-kit inhibition for targeting chronic severe asthmatic responses.

Hypereosinophile Dermatitis

BACKGROUND

The idiopathic hypereosinophilic syndrome is a rare systemic disease characterized by blood and tissue eosinophilia of unknown etiology, in which multiple organs may be affected. In hypereosinophilic dermatitis the only affected organ besides the blood is the skin.

PATIENTS

We present a series of seven patients with hypereosinophilic dermatitis who were treated in our hospital between 2002 and 2003.

RESULTS

All patients initially showed characteristic, therapy-resistant, polymorphic skin lesions, presenting with a combination of erythematous, pruritic and urticarial papules and plaques. All had blood eosinophilia without evidence of allergic, parasitic or other causes. The histology showed tissue eosinophilia only in half of the cases; the other histological findings were non-specific. We observed a good response to therapy with systemic corticosteroids, dapsone and light therapy, applied as UVA-1 irradiation or as shower photochemotherapy.

CONCLUSIONS

The diagnosis "hypereosinophilic dermatitis" should be based primarily on the characteristic clinical picture together with "idiopathic" peripheral eosinophilia, whereas the histological findings are not always indicative. Because of the multiplicity of possible differential diagnoses and the often non-revealing histology, we assume that the diagnosis "hypereosinophilic dermatitis" is often overlooked.

Manifestations cardiaques du syndrome hyperéosinophilique essentiel

BACKGROUND

The aim of our study is to describe the more common cardiac manifestations of idiopathic hypereosinophilic syndrome representing the major cause of mortality.

MAIN POINTS

Current therapy consists of corticosteroid, hydroxyurea and interferon alpha. Recent publications confirm the activity of imatinib mesylate, a selective tyrosine kinase inhibitor, in patients with idiopathic hypereosinophilic syndrome. In cases with marked valvular compromise or with endomyocardial thrombosis or fibrosis, cardiac surgery can provide substantial benefits.

PERSPECTIVES

A better understanding of the pathophysiology of this syndrome could lead to the development of new therapeutic agents.

Conventional cytogenetics of myeloproliferative diseases other than CML contribute valid information

In chronic myeloproliferative disorders other than CML (CMPD) recurrent cytogenetic abnormalities occur, but specific patterns of chromosomal aberrations in the specific entities have so far not been detected. Thus, the value of conventional cytogenetics in the routine diagnostic setting of CMPD remains to be clarified. We performed a cytogenetic study on 409 patients with different CMPD [polycythemia vera, essential thrombocytosis (ET), idiopathic osteomyelofibrosis, chronic myelomonocytic leukemia (proliferative subtype), idiopathic hypereosinophilic syndrome (HES), myeloproliferative syndrome (unclassifiable)] and on 102 patients with suspected CMPD. Cytogenetic abnormalities occurred in different frequencies ranging from 3 to 40% depending on the subtype, and showed some specific differences with respect to their type. The highest frequency and the most complex pattern of clonal aberrations were observed in idiopathic osteomyelofibrosis. However, clonal aberrations were also found in 10% of patients with suspected CMPD establishing the diagnosis of a malignant disease. In conclusion, cytogenetics are essential in the routine diagnostic setting of CMPD or cases suspicious for CMPD. In ET and in HES the aberration rate was only 3 and 7%, respectively. Thus, cytogenetics can be omitted. However, in some of these cases molecular procedures should be integrated into the routine diagnostic process.

Treatment of cockroach allergen asthma model with imatinib attenuates airway responses

In the present study it was determined whether a pharmacologic approach to blocking receptor tyrosine kinase-mediated activation during allergic airway responses could be beneficial. To examine these responses, allergic mice were given a single oral dose of imatinib at clinically relevant concentrations, ranging from 0.05 to 50 mg/kg, by oral gavages just before allergen challenge. The reduction in the allergen-induced responses was significant and centered on reducing overall inflammation as well as pulmonary cytokine levels. In particular, the treatment of the mice with imatinib significantly attenuated airway hyperreactivity and peribronchial eosinophil accumulation, and significantly reduced Th2 cytokines, interleukin-4 and interleukin-13. In addition, chemokines previously associated with allergen-induced pulmonary disease, CCL2, CCL5, and CCL6, were significantly reduced in the lungs of the imatinib-treated animals. Together these data demonstrate that the pharmacologic inhibitor imatinib may provide a clinically attractive therapy for allergic, asthmatic responses.