Recombinant alpha-2 interferon in the treatment of hairy cell leukemia.

We treated 14 patients with hairy cell leukemia, 13 of whom had progressive disease, with recombinant alpha-2 interferon administered sc at 2 X 10(6) units/m2, three times per week. Thirteen patients were evaluable for response. All evaluable patients responded within 6-8 weeks. After a minimal treatment duration of 6 months and a maximal of 12 months, three patients have achieved complete response and ten have achieved partial response. With a median treatment duration of 10 months, the responding patients' hematologic parameters are continuing to improve, and no responding patients have relapsed. This outpatient self-administered regimen is well-tolerated, with mild fever, myalgias, and headache usually resolving within 2 months. Although the optimal regimen and the mechanism of action are unknown, recombinant alpha-2 interferon may be the treatment of choice for patients whose disease progresses after splenectomy or who are not surgical candidates.