Ten patients with hairy cell leukemia (HCL) requiring therapy were treated with recombinant beta-serineinterferon (rIFN-Bser) (90 X lo6 units [Ul 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-Bser has activity in HCL.
Cancer 64:409-413, 1989.
AIRY CELL LEUKEMIA (HCL) is a lymphoproliferative H disorder characterized by pancytopenia, splenomegaly, circulating lymphocytes containing the tartrateresistant isoenzyme of acid phosphatase (TRAP), and infiltrated bone marrow that is difficult to aspirate.' Until recently, splenectomy was the only effective treatment for HCL patients requiring therapy.' Currently, alphai n t e r f e r ~n ~-~ and pentostatin' have shown efficacy in improving hematologic variables in patients with HCL.
Alpha-interferons and beta-interferons are type I interferons, sharing approximately 40% amino acid homology and acting on cells through a common receptor. In vitro, both alpha-interferons and beta-interferons inhibit proliferation by hairy cells stimulated by B-cell growth factor.* We report the results of a Phase I1 trial of recombinant beta-serine-interferon (rIFN-pser) in patients with HCL requiring interferon therapy.
Due to emerging data at the time this trial was initiated suggesting that alpha-interferon represented the treatment