• Susan Branford, Timothy Hughes, Alvin Milner, Rachel Koelmeyer, Anthony Schwarer, Chris Arthur, Robin Filshie, Susan Moreton, Kevin Lynch, and Kerry Taylor.
• Division of Molecular Pathology, Institute of Medical and Veterinary Science, Adelaide, SA, Australia. susan.branford@imvs.sa.gov.au
• Cancer. 2007 Aug 15; 110 (4): 801-8.

BackgroundInterferon-alpha (IFN-alpha) confers a survival advantage for the minority of patients with chronic myeloid leukemia (CML) who achieve a complete cytogenetic response. The question of whether IFN-alpha-responsive patients can experience further improvements with imatinib has not been answered. Imatinib offers clear quality of life advantages. Furthermore, patients who achieve a major molecular response (MMR) while receiving imatinib are likely to remain progression free.MethodsA total of 23 patients treated for a median of 4.5 years with IFN-alpha (range, 1.6-14.3 years) who had achieved a complete (Philadelphia chromosome [Ph] negative, n = 15 patients) or near-complete (1-10% Ph, n = 8 patients) cytogenetic response were studied. The primary objective was to determine whether ceasing therapy with IFN-alpha and switching to 12 months of imatinib treatment at a dose of 400 mg/day could improve the molecular response as assessed by real-time quantitative polymerase chain reaction of BCR-ABL transcript levels. Safety was also assessed.ResultsEvery patient who had not achieved an MMR while receiving IFN-alpha (n = 16 patients) achieved an MMR after a median of 3 months of imatinib treatment. Significant BCR-ABL reductions (median, 63-fold; range, 18-425-fold) occurred in 15 of these patients. Every patient who had already achieved an MMR while receiving IFN-alpha (n = 7 patients) maintained an MMR while receiving imatinib. No patients discontinued imatinib due to toxicity, but 1 patient withdrew consent.ConclusionsThese data suggest that switching IFN-alpha-responsive patients to imatinib leads to a rapid improvement in achieving an MMR, a response with established prognostic value, and is well tolerated. The study should help patients and their physicians make evidence-based decisions regarding the potential benefits and risks of switching to imatinib.

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