Low protein expression of MET in ER-positive and HER2-positive breast cancer.

AIM

The mesenchymal-epithelial transition factor (MET) is a receptor tyrosine kinase that plays a key role in cell survival, growth, angiogenesis and metastasis. Because its expression is frequently altered in tumors, MET is currently under investigation as a potential target for anticancer therapy. The purpose of the present study was to determine the prognostic value of tumor MET expression levels in patients with estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-positive breast cancer, in order to strengthen the rationale for targeted therapy using MET inhibitors in this breast cancer subpopulation.

MATERIALS AND METHODS

We determined the expression of MET in formalin-fixed paraffin-embedded surgical specimens of ER- and HER2-positive breast cancer by immunohistochemistry.

RESULTS

Comparisons of MET expression with clinical parameters, including survival of the patients, were performed with MET expression as a dichotomized variable classified as high or low. Out of 78 tumors, 3 (3.8%) showed high MET expression. The analysis examining the association between MET and survival did not yield any statistically significant result regarding overall survival or disease-free survival.

CONCLUSION

ER- and HER2-positive breast carcinomas do not exhibit high MET expression. This null finding, the first to be reported in the literature, is of great importance, since it indicates that this sub-group population is not proper candidate for clinical trials with MET inhibitors.