Expression of gamma-glutamyl transpeptidase in stage III and IV ovarian surface epithelial carcinomas does not alter response to primary cisplatin-based chemotherapy.

Abstract

Gamma-glutamyl transpeptidase activity has been shown to be essential for the nephrotoxicity of cisplatin. The purpose of this study was to determine whether expression of gamma-glutamyl transpeptidase in ovarian carcinomas is necessary for the antitumor effect of cisplatin. Tumor tissue from 18 patients with stage III or IV ovarian serous papillary carcinoma or poorly differentiated adenocarcinoma was analyzed for expression of gamma-glutamyl transpeptidase by histochemical or immunohistochemical staining. Response to cisplatin-based combination chemotherapy was evaluated on the basis of clinical response, progression-free interval, and survival. Gamma-glutamyl transpeptidase expression in the tumors ranged from 0% to 100% of the tumor cells gamma-glutamyl transpeptidase positive. Patient survival ranged from 15 months to 9 years. Twelve of the 18 patients had a complete response to the initial course of cisplatin-based combination chemotherapy. There was no statistically significant correlation between either response or time to relapse and gamma-glutamyl transpeptidase expression. However, there was a correlation between high levels of gamma-glutamyl transpeptidase in the tumor and acute ototoxicity in patients treated with cisplatin. Expression of high levels of gamma-glutamyl transpeptidase in the tumor was also found to be associated with shorter patient survival, suggesting that gamma-glutamyl transpeptidase might have a role in resistance to drugs used in second- and third-line therapy. Expression of gamma-glutamyl transpeptidase in ovarian serous papillary or poorly differentiated adenocarcinomas is not necessary for the antitumor activity of cisplatin. A correlation was found between high levels of gamma-glutamyl transpeptidase in the tumor and both increased ototoxicity from cisplatin and decreased patient survival. These data suggest that administering an inhibitor of gamma-glutamyl transpeptidase activity to block the nephrotoxicity of cisplatin would not interfere with its therapeutic effect.