Amplification of the mdr1-gene is uncommon in recurrent ovarian carcinomas

Ovarian carcinomas are known to rapidly develop drug resistance against che motherapeutic agents. This phenomenon is often associated with the expressi on of p170-glycoprotein. A high rate of transcription of the corresponding mdr1-gene in resistant tumors is reported. Amplification of the mdr1-gene h as been observed in tumor cell lines exposed to cytotoxic drugs; however, s ignificant information is lacking as to whether this holds true in clinical carcinomas. To fill this gap, we investigated the rate of gene amplificati on of the mdr1-gene in 63 recurrent ovarian carcinomas and we determined th e resistance pattern of these cells using an ex vivo assay. The tumors show ed varying ex vivo resistance patterns which did not correlate to clinical parameters. Amplification of the mdr1-gene was not observed in any of the c ancer specimens. Therefore, we conclude that mdr1-gene amplification is not a common pathway for the development of chemoresistance in clinical ovaria n carcinomas. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.