Low Dose Interferon Alfa-2B for the Induction of Remission of Hairy Cell Leukemia: A Multi-institutional Study of 49 Patients.

This multicenter study reports on 49 patients with hairy cell leukemia (HCL) who were treated subcutaneously with alfa-2b interferon (Intron A, Schering Corporation, Kenilworth, N.J.), three times a week at a reduced dosage of 200,000 units/m(2), one-tenth the dose of the standard 2 million units/m(2). The response rate (normalized blood counts) was 22% (11 of 49); an additional 12 patients had a minor response for an overall response rate of 47% (23 of 49). When response was assessed by prior IFN therapy, no significant difference was noted. Five of 21 (24%) with no prior IFN and 6 of 28 (21%) with prior IFN therapy achieved at least a normalization of blood counts (p = 0.07). The response rate with low-dose interferon is inferior to that with standard dose interferon and should not be used for remission induction, but should be evaluated for its role in long-term maintenance of response.