Efficacy and safety of imatinib in patients with chronic myeloid leukemia and complete or near-complete cytogenetic response to interferon-α

✍ Scribed by Susan Branford; Timothy Hughes; Alvin Milner; Rachel Koelmeyer; Anthony Schwarer; Chris Arthur; Robin Filshie; Susan Moreton; Kevin Lynch; Kerry Taylor

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 201 KB
• Volume: 110
• Category: Article
• ISSN: 0008-543X
• DOI: 10.1002/cncr.22842

✦ Synopsis

Abstract

BACKGROUND.

Interferon‐alpha (IFN‐α) 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‐α‐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.

METHODS.

A total of 23 patients treated for a median of 4.5 years with IFN‐α (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‐α 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.

RESULTS.

Every patient who had not achieved an MMR while receiving IFN‐α (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‐α (n = 7 patients) maintained an MMR while receiving imatinib. No patients discontinued imatinib due to toxicity, but 1 patient withdrew consent.

CONCLUSIONS.

These data suggest that switching IFN‐α‐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. Cancer 2007. © 2007 American Cancer Society.