CORRELATION BETWEEN EXTREME DRUG-RESISTANCE ASSAY AND RESPONSE TO PRIMARY PACLITAXEL AND CISPLATIN IN PATIENTS WITH EPITHELIAL OVARIAN-CANCER

Objective. The extreme drug resistance (EDR) assay has been correlated with failure of response to chemotherapy in greater than 99% of patie nts. The goal of this study is to correlate the results of the EDR ass ay to response to first-line paclitaxel/cisplatin among patients with epithelial ovarian cancer. Methods. Seventy-five of 100 patients with epithelial ovarian cancer for whom EDR assay war, performed were treat ed with weekly induction cisplatin (1 mg/kg body wt) x 4, followed by monthly paclitaxel (135 mg/m(2)) and cisplatin (75 mg/m(2)) x 6 and we re evaluable for correlation of response to chemotherapy and EDR assay . Specimens for EDR assay were obtained at primary surgery and the EDR assay was performed by Oncotech, Inc. Response to chemotherapy was co rrelated to EDR assay results regarding paclitaxel and cisplatin. Resu lts, Among 75 evaluable patients, the prevalence of EDR to paclitaxel was 20.0% (n = 15) and to cisplatin it was 2.7% (n = 2). Only 1 patien t (1.3%) exhibited EDR to both paclitaxel and cisplatin. Surgical asse ssment of response was performed in 42 patients; 33 patients were clin ically evaluable. The overall response rate was 85.3%. The overall res ponse rate for patients whose tumors demonstrated no EDR to either pac litaxel or cisplatin did not differ significantly from that for patien ts whose tumors demonstrated EDR to at least one of these two drugs (8 6.4% versus 81.3%, respectively, P = 0.692), Similarly, the complete s urgical response rate for both groups did not differ significantly (25 .4% versus 12.5%, respectively, P = 0.34). A single patient whose tumo r exhibited EDR to both paclitaxel and cisplatin had tumor progression . The sensitivity, specificity, positive predictive value, and negativ e predictive value of the EDR assay were 79.6, 27.0, 86.0, and 19.0%, respectively, Conclusions. EDR to paclitaxel does not preclude respons e to the combination of paclitaxel and cisplatin as primary therapy fo r patients with epithelial ovarian cancer. The role of the EDR assay i n the primary management of patients with epithelial ovarian cancer re mains to be determined. (C) 1998 Academic Press.