Additional Her 2/neu gene copies in patients with Sézary syndrome

BackgroundHer 2/neu gene amplification has been reported in several types of cancer. Monoclonal antibodies against the Her 2/neu receptor are used as a treatment in e.g. metastatic breast cancer.AimThe aim of this study was to determine the frequency of additional Her 2/neu gene copies in relations to the number of chromosome 17 centromeres of patients with Sézary syndrome.MethodsFluorescence in situ hybridization (FISH) with probes specific for the Her 2/neu gene locus and the centromere of chromosome 17 was performed on nuclei from peripheral blood cells of 9 patients with Sézary syndrome. For analysis of Her 2/neu protein expression immunostaining was performed. In addition, FISH was used to analyze distribution of typical lymphocytes on cryo-cut sections of affected skin of two patients.Results7/9 cases showed additional Her 2/neu gene copies in relation to the number of chromosome 17 centromeres. 4/5 cases with additional Her 2/neu gene copies in which immunostaining was performed expressed Her 2/neu protein. On cryo-cut sections atypical lymphocytes with additional Her 2/neu gene copies were detected in the dermis as well as in the epidermis of affected skin.DiscussionThese data suggest that Her 2/neu might be involved in the pathogenesis of Sézary syndrome and that Her 2/neu might be a promising target for antitumor therapy in a subgroup of patients.