A Prospective Randomized Study of Alpha-2b Interferon plus Hydroxyurea or Cytarabine for Patients with Early Chronic Phase Chronic Myelogenous Leukemia: The International Oncology Study Group CML1 Study

A prospective randomized international study of 143 patients showed no apparent early survival advantage conferred by combining cytarabine, rather than hydroxyurea, with INF as first-line CML therapy. Combinations of alpha-interferon (INF) and chemotherapeutic agents are currently first-line therapy for the majority of patients with chronic myeloid leukemia (CML). The International Oncology Study Group conducted a prospective randomized study comparing INF combined with hydroxyurea or cytarabine. The primary study aim was to compare the survival durations in these patient cohorts. Patients with early chronic phase CML were randomized to receive INF 5 million units (Mu) given five times per week subcutaneously plus hydroxyurea or cytarabine as required to achieve a complete hematologic response and to maintain a WBC count between 2x10(9)/L and 10x10(9)/L and a platelet count between 75x10(9)/L and 100x10(9)/L. Therapy continued as tolerated unless progressive or blast phase disease occurred. At 36 months, the actuarial survival rate was equivalent in both groups: HI group (79 patients) survival was 85% (95% CI, 68-100%), as compared to 95% (95% CI, 79-100%) in the CI group (64 patients). In conclusion if seems that there is no apparent early survival advantage conferred by combining cytarabine, rather than hydroxyurea, with INF as first-line CML therapy.