Extreme drug resistance assay and response to chemotherapy in patients with primary peritoneal carcinoma

Background and Objectives: The extreme drug resistance (EDR) assay is an in vitro chemoresistance assay performed on tumor samples grown in culture an d is claimed to predict drugs unlikely to produce response. its clinical va lue in patients with epithelial ovarian cancer (EOC) has recently been ques tioned. The aim of this study is to describe EDR assay results and response s to chemotherapy among women with primary peritoneal adenocarcinoma (PPA) and to compare them with those of women with EOC. Methods: Fresh tumor specimens from 20 consecutive women with PPA were test ed for EDR to the following drugs: cisplatin, carboplatin, paclitaxel, doxo rubicin, cyclophosphamide, ifosfamide, etoposide, hexamethylmelamine, and t opotecan. They were then treated with cisplatin-based combination chemother apy. The results of the EDR assay and response to chemotherapy were compare d with those among women with EOC. Results: Then was no significant difference in the incidence of EDR to cisp latin, carboplatin, paclitaxel, doxorubicin, cyclophosphamide, ifosfamide, etoposide, hexamethylmelamine, and topotecan among patients with PPA and th ose with EOC. The response rate of PPA patients to chemotherapy was 80.0% a nd unrelated to EDR to the individual drugs used in combination chemotherap y. Conclusions: The EDR profile and response to cisplatin-based chemotherapy a mong women with PPA were similar to those among women with EOC. These findi ngs support treating both conditions similarly. EDR to individual drugs doe s not preclude response to combination chemotherapy. (C) 2000 Wiley-Liss, I nc.