AbstractSeventeen patients with metastatic breast cancer who had failed prior chemotherapy were treated with intravenous AZQ at a dose of 15-20 mg/m2weekly for four consecutive weeks followed by a two-week rest period. No responses were observed. Myelosuppression was the dose-limiting toxicity. One patient experienced massive liver infarction possibly related to AZQ. Our data suggest that this agent at the schedule and dosage used is of no benefit in pretreated breast cancer patients.