Phase-I study of continuous infusion cyclophosphamide for protracted durations: a preliminary report

The continuous infusion of cyclophosphamide with an ambulatory infusion pump was employed in 13 patients to establish the optimal daily dose rate for permitting prolonged treatment intervals. Four dose rates were studied: 25, 50, 75, and 100 mg/M2 X day and the median duration of therapy was 39, 13, 20, and 28 days, respectively, with a range of 10-50 days. Dose-limiting toxicity was observed in 4 of 13 patients manifested exclusively as thrombocytopenia. No other drug-related untoward effects were observed and no therapeutic effects were noted. The cumulative cyclophosphamide dose for 3 weeks of continuous infusion is comparable to that achieved by bolus schedules. Drug toxicity, however, is substantially altered with the infusion schedule. For good-risk patients, the recommended daily infusion rate for cyclophosphamide is 100 mg/M2 X day.