INTERFERON ALFA-2A AS COMPARED WITH CONVENTIONAL CHEMOTHERAPY FOR THETREATMENT OF CHRONIC MYELOID LEUKEMIA

Background. In view of studies showing that interferon alfa was effect ive treatment for chronic myeloid leukemia and that it prolonged survi val, we organized a prospective, controlled comparative study of this treatment. Methods. We compared recombinant interferon alfa-2a with co nventional chemotherapy (hydroxyurea or busulfan) in a trial designed to have a power of 80 percent to detect a difference of 20 percent in median survival between the group given interferon and the group given conventional chemotherapy. Between 1986 and 1988, 322 patients with p reviously untreated or minimally treated Philadelphia chromosome-posit ive chronic myeloid leukemia were randomly assigned to treatment with either interferon alfa-2a (218 patients) or conventional chemotherapy (104 patients). Results. The rate of karyotypic response (defined as > 33 percent of metaphases negative for the Philadelphia chromosome) was 30 percent in the interferon groupand 5 percent in the conventional-c hemotherapy group (P<0.001). The time to progression from the chronic phase of leukemia to an accelerated or a blastic phase was longer in t he interferon group than in the conventional-chemotherapy group (media n, >72 vs. 45 months; P<0.001), as was survival (median, 72 vs. 52 mon ths; 6-year survival, 50 percent vs. 29 percent; P = 0.002 for both co mparisons). There was one treatment-related death in each group. Treat ment was discontinued because of side effects (mainly influenza-like, gastrointestinal, or neurologic symptoms) in 35 patients given interfe ron alfa-2a (16 percent). The cost of interferon treatment was 200 tim es that of the conventional treatment. Conclusions. During long-term t reatment of Philadelphia chromosome-positive chronic myeloid leukemia, interferon alfa-2a induced more karyotypic responses than conventiona l chemotherapy, delayed disease progression longer, and prolonged over all survival more.