¹First Department of Surgery, University of Yamanashi, 1110 Shimokato, Chuo-city, Yamanashi 409-3898, Japan

Correspondence: Dr K Kono, E-mail: kojikono@yamanashi.ac.jp

Revised 16 April 2007; Accepted 20 June 2007; Published online 10 July 2007.

Abstract

We previously reported that oesophageal squamous cell carcinoma (SCC) had a relatively high incidence of EGFR and HER-2 overexpression. Thus, anti-HER family targeting may become a promising approach to treat oesophageal SCC. In the present study, we investigated (a) the distribution of EGFR and HER-2 expression in oesophageal SCC (n=66) detected by immunohistochemistry and (b) cetuximab- and/or trastuzumab-mediated biological activity (antiproliferative effect by the MTT assay, apoptosis-inducing activity by the annexin V/propidium iodide assay, and antibody-dependent cellular cytotoxicity (ADCC) by the ⁵¹Cr-release assay) against oesophageal SCC cell lines with various levels of EGFR and HER-2. Twelve of the 66 patients (18%) showed both EGFR- and HER-2 expression. Out of both EGFR- and HER-2-positive cases, nine cases (75%) showed EGFR and HER-2 expression in individually distinct regions. Furthermore, the combination of cetuximab and trastuzumab could induce synergistic antiproliferative effects and additional ADCC activities against not all, but several oesophageal SCC cell lines with EGFR and HER-2 expression. The combination of cetuximab and trastuzumab may be useful in the treatment of oesophageal SCC with EGFR and HER-2 expression.