Cytarabine added to interferon improves the cost-effectiveness of initial therapy for patients with early chronic phase chronic myelogenous leukemia

The French Chronic Myeloid Leukemia Study Group prospective randomized study results indicate that the addition of cytarabine to alpha interferon (IFN-α) increases the rate of major cytogenetic response and prolongs survival in patients with early chronic phase chronic myelogenous leukemia (CML). The French group study design permitted a single crossover to include or discontinue cytarabine or interferon. Endpoints were overall survival, complete hematologic remission (CHR) at six months, and major cytogenetic response at 12 months. We modified a published Markov model that compared IFN-α alone to IFN-α plus cytarabine and included the possibility of crossover as in the French study. The model permits allogeneic and autologous stem cell transplantation (SCT), and follows cytogenetic response and acceleration of CML through death. Treatment response, toxicity, and survival are drawn from the French Chronic Myeloid Leukemia Study Group population of 810 patients on an intention-to-treat model. Survivals are extended to 62 months based on currently available follow-up. Costs from a United States oncology specialty institution, and state utilities from previous research and a quality-adjusted Time Without Symptoms or Toxicity analysis of the subject study were discounted at 3% per annum. At the median cohort age of 50, cytarabine offers 21 months of added median survival to IFN-α, which itself is superior to conventional chemotherapy by 21 months. Cost-effectiveness estimates for cytarabine added to IFN-α range from $7,000 per quality-adjusted life year (QALY) to $35,000 per QALY, under all plausible assumptions superior to IFN-α alone. The model is sensitive to the quality of life on therapy, as well as to remission rate with additive cytarabine, although the cost-effectiveness calculations are robust over the entire range of clinical assumptions. Based on data from the French study, cytarabine added to IFN-α substantially improves the cost-effectiveness of initial therapy for early chronic phase CML.