Low-dose interferon alfa-2b in the treatment of hairy cell leukemia.

Twenty-two patients with hairy cell leukemia were treated with low-dose interferon alfa-2b (0.2 X 10(6) U/m2 given three times weekly) for 6-12 months. The overall response rate was 54%, with only 18% complete plus partial responses. The therapy had to be terminated early in five of these patients because their progressive disease led to severe cytopenia. Although the toxic effects with this regimen were minimal, the significantly lower response rate and the poorer quality of the responses prohibit its use as initial therapy in hairy cell leukemia.