BACKGROUND Prostate cancer is the most common malignancy in American men, and as many as 70% of those initially treated for localized disease will ultimately progress and be considered candidates to receive therapy for metastatic cancer [Fuks et al.: Int J Radiat Oncol Bio Phys 21:537-547, 1991; Chodak et al.: N Engl J Med 330:246-248, 1994]. Although most will respond initially to hormone manipulation, essentially all will fail and require additional therapy. No standard chemotherapy approach has been shown to prolong survival significantly, and new agents are desperately needed. Topotecan is a new topoisomerase-1 inhibitor whose early investigation suggested possible activity in hormone-refractory prostate cancer. METHODS In this phase II trial, patients having failed one or two prior androgen ablative therapies were treated with 21-day continuous intravenous infusions of topotecan at a dose of 0.5 mg/m(2) per day every 28 days. RESULTS Twenty-six eligible patients were entered on the study. There were no confirmed tumor responses. Median survival was 9 months. The most common toxicities were hematologic, with 8 of 24 assessable patients experiencing grade 4 toxicity. CONCLUSIONS Topotecan infusions at this dose are ineffective in the management of hormone-refractory prostate cancer.