In view of the bone marrow toxicity seen with topotecan and the poor patient acceptance of a five day schedule, there has been interest in the development of an effective alternate treatment regimen using topotecan. Results from preclinical studies suggest that repeated administration of topotecan is necessary for its activity. A phase I study evaluating the safety and efficacy of weekly bolus topotecan as a second line agent in relapsed ovarian cancer resulted in a maximum tolerated dose of 5 mg/m2.