Survival benefit with imatinib mesylate versus interferon-alpha-based regimens in newly diagnosed chronic-phase chronic myelogenous leukemia.
A survival benefit for imatinib mesylate versus interferon-alpha therapy could not be demonstrated in the randomized study in newly diagnosed Philadelphia chromosome (Ph)-positive chronic-phase chronic myelogenous leukemia (CML) due to the high rate of crossover (90%) from interferon-alpha to imatinib mesylate within a year of study entry. We compared survival in 279 patients with newly diagnosed CML treated with imatinib mesylate at our institution (2000-2004) to 650 patients treated with interferon-alpha (1982-1997). The complete cytogenetic response rates were 87% with imatinib mesylate and 28% with interferon-alpha (P < .001). The estimated 3-year survival rates were 96% with imatinib mesylate and 81% with interferon-alpha (P < .01). Survival rates with imatinib mesylate were significantly better than with interferon-alpha within each of the CML prognostic risks groups. By multivariate analysis, imatinib mesylate therapy was identified as an independent favorable prognostic factor, after accounting for the impact of pretreatment factors (hazard ratio, 0.44; P < .01). By landmark analysis at 12 months, survival within each cytogenetic response category was similar with imatinib mesylate or interferon-alpha, suggesting that the survival benefit of imatinib mesylate (versus interferon-alpha in newly diagnosed CML) is through improving cytogenetic response.