[Phase I clinical study of SH L573 (fludarabine phosphate) in patients with chronic lymphocytic leukemia and adult T-cell leukemia/lymphoma].

We have conducted a phase I clinical study of fludarabine phosphate, a new purine nucleoside derivative, in patients with chronic lymphocytic leukemia and adult T-cell leukemia/lymphoma. The patients were given intravenous administration at a dose of 15 mg/m2/day followed by 20 mg/m2/day and 25 mg/m2/day, each dose given consecutively for 5 days. The dose limiting factors were thrombocytopenia and neutropenia. The thrombocyte count and neutrocyte count dropped to their lowest value in week 1 to 2 after administration, but the changes were reversible, and these counts recovered in most patients. The maximum tolerated dose of the study drug was 25 mg/m2/day, and it was decided to administer 20 mg/m2/day as the recommended dose for the subsequent phase II clinical study.