Low-dose cladribine for symptomatic hairy cell leukaemia.

Cladribine is an effective therapy for hairy cell leukaemia (HCL), but the standard regime is frequently complicated by neutropenic fever and prolonged T-cell depression. We studied 102 patients with active HCL following treatment with various doses of cladribine given for 7 d. Two patients received 1 mg cladribine/m2/d without toxicity or effect. Eight subsequent patients received 2 mg cladribine/m2/d, and normalized cytopenia as quickly as 94 control patients receiving a standard dose (3.4 mg/m2 or 0.085 mg/kg), with significantly less lymphopenia and a similar complete remission rate.