Phase II study of mifepristone (RU486) in refractory ovarian cancer

A phase II study of Mifepristone (RU486) was conducted in patients with ovarian cancer whose tumors were resistant to cisplatin and paclitaxel, alone or in combination.

Forty-four patients were accrued into this study. All had ovarian cancer that had become resistant to cisplatin and paclitaxel. Patients received Mifepristone 200 mg orally on a daily basis. Patients were followed by tumor size or CA-125 levels when there was no measurable disease. A dose reduction of Mifepristone was to occur in the event of grade 3/4 hematologic, GI, or liver toxicity, creatinine >2.5%, and grade 4 peripheral neuropathy.

Thirty-four patients were evaluable for response. Nine (26.5%) of these patients had a response to Mifepristone. Three(9%) patients had a complete response, and six (17.5%), a partial response. The response of one patient in each group was measured by CA-125 levels while the remainder had measurable disease. The response lasted 1 to 4 months in all but one patient. One patient continues to respond after more than 3 years. The major toxic effect was a rash and this was the major reason patients were removed from the study.

Mifepristone has activity against ovarian cancer resistant to cisplatin and paclitaxel. The drug is well tolerated. Further studies need to be performed when this drug becomes more widely available in the United States.