Treatment with low dose human recombinant interferon-alpha-2-ARG induces complete remission in patients with hairy cell leukemia.

Five cases with advanced hairy cell leukemia refractory to treatment with splenectomy and chemotherapy as well as one patient presenting with a stage-A response to splenectomy were treated with rhu-IFN-α2-arg. 5 × 106 were administered intramuscularly every day. Both patients, with advanced disease resistant to conventional therapy and treated for six or more months with rhu-IFN-α2-arg, achieved complete clinical remissions. Three further cases treated for less than half a year and also with advanced disease achieved partial remission states with marked reduction of circulating hairy cells and with recovery of normal hemopoiesis. Minimal residual disease in the remaining patient during a three-month period of treatment did not respond. Side effects of rhu-IFN-α2 low dose therapy were minimal in 5 cases and comprised a severe leukopenia reversible after dose reduction in one patient.