Paclitaxel, estramustine, and etoposide in the treatment of hormone-refractory prostate cancer.

We previously developed a novel and effective therapy for hormone-refractory prostate cancer using the agents estramustine and etoposide. Although neither of these agents alone is effective in the treatment of advanced, hormone-refractory prostate cancer, we predicted their activity when used in combination based on preclinical assays, and then demonstrated their effectiveness in a phase I-II clinical trial, where they were shown to produce a 50% complete and partial response rate in patients with bidimensionally measurable disease. In preclinical studies, we had demonstrated that estramustine and etoposide interact with the nuclear matrix, which is the site of DNA replication. Expanding these investigations, we determined that paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), a microtubule inhibitor, interacts with estramustine and etoposide, and the combination of these three agents had significant preclinical activity against androgen-independent prostate cancer cells. These studies led us to conduct a phase II clinical trial of paclitaxel, estramustine, and etoposide in patients with hormone-refractory prostate cancer. Preliminary results demonstrate that this is an active regimen, with 57% of patients demonstrating a response to therapy as measured by a decrease in pretreatment prostate-specific antigen levels of greater than 50%.