Recombinant beta‐serine‐interferon in hairy cell leukemia compared prospectively with results with recombinant alpha‐interferon

Ten patients with hairy cell leukemia (HCL) requiring therapy were treated with recombinant beta‐serineinterferon (rIFN‐βser) (90 × 106 units [U] subcutaneously three times a week). Eight patients were evaluable for response and nine for toxicity. Five patients (63%) showed normalization of peripheral blood counts, and an additional two patients (25%) showed improvement in at least one hematologic variable. Persistent hairy cells were detected in the bone marrow of all patients at the completion of therapy. All patients experienced influenza‐like symptoms which were not dose limiting and which resolved with continued therapy. Erythema and induration at interferon injection sites developed in five patients (56%); one required dose reduction and another was removed from the study for this reason. Data from matched historical controls treated with recombinant alpha‐interferon are presented for comparison. We conclude that rIFN‐βser has activity in HCL.