Phase II study of estramustine, oral etoposide, and vinorelbine in hormone-refractory prostate cancer

Hormone-refractory prostate cancer is characterized by a low response rate following second-line therapy. Encouraging results have been reported in Phase II studies with estramustine associated with vinblastine or etoposide. Vinorelbine is a new semisynthetic vinca alkaloid that has demonstrated activity in prostate cancer. We therefore evaluated the activity of the following schedule: estramustine, 400 mg/m² orally days 1-42; etoposide, 50 mg/m² orally days 1-14; and 28-42; vinorelbine, 20 mg/m² days 1, 8, 28, and 35; cycles being repeated every 8 weeks. Twenty-five patients have been included and are assessable for response and side effects. Patient characteristics were as follows: median age, 71 years (range 55-81); ECOG performance status 0-2; nonosseous disease, 3 cases; bone metastases, 23 cases. Sixty-two cycles have been delivered. Two patients with measurable disease and six patients with bone disease had a partial remission for an overall response rate of 32% (95% confidence interval 15-53%). Seven patients had stabilization of disease and 10 had progression of disease. Median duration of response was 3 months (range 2-5). Prostate-specific antigen in 14 patients (56%) decreased from baseline by at least 50%. Toxicity was manageable. Neutropenia was mild, with only three cases of grade Ill-IV toxicity. Two patients had severe anemia. The results of this study indicate that the schedule is active and well tolerated in hormone-refractory prostate cancer patients.