Combined interferon alfa-2a and cytosine arabinoside as first-line treatment for chronic myeloid leukemia.

Thirty patients with chronic myeloid leukemia in chronic phase and less than 1 year from diagnosis were treated with a combination of interferon alfa-2a (IFN) 9 million units daily continuously and intermittent low-dose cytosine arabinoside (Ara-C) 20 mg/m2 daily for 21 days every 42 days. The leukemia was controlled initially with hydroxyurea prior to commencing IFN and Ara-C. The treatment was continued for at least 12 months after which time nonresponders were withdrawn from the trial and responders continued on IFN alone. The median duration of follow-up is 14 months (range 10-53 months). Hematological response was assessed by clinical and laboratory parameters and cytogenetic response was assessed by regular bone marrow chromosome analysis. A complete hematological response occurred in 28/30 patients (93%). A complete cytogenetic response (no detectable Philadelphia chromosome-positive metaphases) was present on at least one occasion in 9/30 (30%), a partial cytogenetic response (between 1 and 34% Philadelphia chromosome-positive metaphases) in 7/30 (23%) and a minor response in 4/30 (13%), giving an overall cytogenetic response rate of 67%. Significant side effects included mucositis, nausea, cytopenia and depression. Side effects could be managed by dose reduction or temporary cessation and were tolerable in most patients, but in 1 patient this led to withdrawal from the trial due to severe depression. Two patients have transformed, 1 to acute lymphoblastic leukemia and 1 to accelerated phase. Two patients have died after exiting the study, both from complications of allogeneic bone marrow transplantation. In conclusion, these results are superior to the results using IFN alone and indicate the need for a randomized study.