Recombinant gamma-interferon has activity in chronic myeloid leukemia.

We demonstrated the clinical effectiveness of recombinant interferon-gamma (rIFN gamma) (Biogen) in 18 patients with Philadelphia-positive chronic myeloid leukemia. Sequential cytogenetic studies and molecular analyses of the breakpoint cluster region and for immunoglobulin and T cell rearrangements were performed every 3-4 months. In 13 patients who received treatment for a minimum of 3 months, the majority were treated with 1.5 mg/m2, t.i.w., i.v. Nonhematologic effects--particularly chills, rigors, myalgia, fatigue, headaches, and nausea--were significant. Complete or partial hematologic responses were observed in six patients, two of whom had approximately 20% normal metaphases after an average of 74 weeks of treatment. However, reversion to 100% Ph+ cells occurred 30 weeks later. In these two patients, in whom normal metaphases were found, no changes were observed in the presence of rearrangements of the breakpoint cluster region. In addition, the marrows remained hypercellular, and the leukocyte alkaline phosphatase score and B12 levels remained abnormal. No immunoglobulin or T cell beta-chain gene rearrangements were found. These data indicate the clinical effectiveness of rIFN gamma in some patients with chronic myeloid leukemia, although the fundamental nature of the disease is unaltered by this form of treatment.