STI571 ProspectIve RandomIzed Trial: SPIRIT (SPIRIT)

Imatinib at 400 mg daily has emerged as the preferred therapy for newly diagnosed CML patients who do not undergo allogeneic stem cell transplant.

A phase III randomized study, comparing imatinib at 400 mg per day to interferon plus cytarabine in newly diagnosed chronic phase CML patients enrolled 1106 patients from June 2000 to January 2001. 553 patients were randomized to each treatment. For comparative purposes, at 6 months, 75% of patients randomized to imatinib obtained a major cytogenetic response with 51% complete responses. Despite these impressive results, only a minority of patients treated with imatinib in this study achieved a molecular remission. When analyzed by log reduction in Bcr-Abl transcript levels using quantitative RT-PCR, 39% of patients achieved a 3-log reduction in Bcr-Abl levels, but only 13% and 3% achieved a 4- and 5-log reduction, respectively.2 To improve upon these results, various groups have tried higher doses of imatinib, and combinations of imatinib with interferon alpha or cytarabine. Each of these studies has used cytogenetic responses as the major endpoint.

Each of these therapies has increased toxicity as compared to 400 mg of imatinib alone and the rates of molecular remissions have not been reported.

Thus the purpose of this study is to first determine whether higher doses of imatinib or combining Imatinib with interferon or Ara-C would result in higher rates of molecular responses and if so, in better survival.