The first phase II study of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) in breast cancer was completed at M.D. Anderson Cancer Center, and included 25 patients with metastatic breast cancer who had been previously treated with one chemotherapy regimen. Fourteen of these patients achieved a major objective response; the median response duration was 9 months, and the median survival time, 20 months. Additional trials showed that paclitaxel maintained its antitumor efficacy in patients with two and three prior chemotherapy regimens, including patients with anthracycline-resistant breast cancer. Combination therapy with doxorubicin showed that this combination was effective, although with the long infusion duration used for both agents, sequence-dependent toxic interactions were encountered. In combination with vinorelbine, dose-limiting toxicity included neutropenic fever and neuropathy. High-dose single-agent paclitaxel is currently being explored in the management of inflammatory breast cancer and as part of neoadjuvant chemotherapy for stages II and III operable disease.