Treatment of chronic myeloid leukemia with interferon alpha (Roferon): results of the Israeli Study Group on CML.

Thirty patients with chronic myeloid leukemia from 11 Israeli medical centers entered this study. Their ages ranged from 16-65 (median 41) and time from diagnosis to treatment was 1-16 months (median 4 months). After cytoreductive therapy with hydroxyurea (22 patients) or busulphan (8 patients), patients received 9 million units/day of recombinant interferon alpha-2 alpha (Roferon A) subcutaneously. Side effects included arthralgia or low back pain in 7 patients, thrombocytopenia in 9, weight loss in four, neurologic disturbances in 4 and leukopenia in 3 cases. Seventeen patients achieved complete hematologic remission (CHR) and 6 partial hematologic remission (PHR). Six patients achieved major cytogenetic response, 4 of them lost all Ph1 chromosome positive cells and 4 had minimal cytogenetic response. Frequency of relapse was high: 8 patients with CHR and 6 with PHR relapsed, but patients with major cytogenetic response did not relapse. Patients who had received prior therapy with busulphan had a higher remission rate but a lower quality of cytogenetic response. Escalation of Roferon to 12 million units per day in relapsing or nonresponding patients induced PHR in 2/7. Neutralizing anti-interferon antibodies occurred in 7 relapsing or nonresponding patients. The cytoreductive induction with hydroxyurea enhanced the hematologic remissions to a median of 6 weeks. Further studies should define the role of combination therapy in order to improve response and prevent relapses.