EGFR Expression and Gene Copy Number in Malignant Pleural Mesothelioma in Turkey

Abstract

Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor prognosis. Standart chemotherapy regimens still remain palliative. There is urgent need for novel therapy options such as targeted therapies in order to improve the outcome of the patients. Epidermal growth factor receptor (EGFR) is a common target for cancer chemotherapy. There is relatively less data in the literature regarding EGFR expression status in MPMs. In this study we analysed EGFR expression immunohistochemically in 21 Turkish MPM cases. As gene amplificaiton is one of the mechanism responsible from receptor overexpression, we also studied EGFR gene copy number by fluorescent in situ hybridization (FISH) method. We found EGFR overexpression in 16/19 (84.2%) cases. EGFR overexpression was seen in all epithelial and most (66,6%) biphasic tumor types. There was, however, no association between EGFR expression and survival. Although we did not find gene amplification, we detected gene copy number increase (e.g., high polysomy) in two cases (9,5%). Gene copy number increase seems to be responsible from EGFR overexpression in only a small percentage of MPM cases. Further studies investigating other potential factors which might be associated with EGFR expression are needed, and more clinical trials are required to evaluate whether MPM patients are candidates for EGFR targeting therapies.