The largest study to evaluate the oral therapy imatinib (Glivec/STI571) in patients with chronic myeloid leukaemia (CML) reported a survival rate of nearly 90% after 5 years of treatment.

Five-year follow-up data from the International Randomized Interferon versus STI571 (IRIS) trial were presented at the American Society of Clinical Oncology annual meeting. IRIS enrolled 1,106 newly-diagnosed Philadelphia chromosome-positive CML patients. Of the 553 patients randomized to imatinib rather than standard therapy, 69% remain on imatinib and, of those, overall survival is 89% and disease-specific survival is 95% after 5 years.

“This trend, if it holds, coupled with the low risk of relapse, means that the possibility of long-term survival with CML is increasingly likely,” said Brian Druker, the lead author of the study at Oregon Health and Science University (http://www.reuters.com, 3 June 2006).

Furthermore, data from the study also showed that the percentage of patients with a complete cytogenetic response actually increased from 69% to 87% between the first and fifth years of treatment. “Very few oncology medicines offer patients the opportunity to achieve better outcomes the longer they take the therapy,” said David Epstein, of Novartis Oncology (http://www.novartis.com, 3 June 2006).

Although imatinib has been heralded as a 'life saver' by patients (http://news.bbc.co.uk, 6 June 2006), Druker, who helped develop imatinib, pointed out that even imatinib has its limits and is not a cure for CML. Over the 5 years of treatment in IRIS, approximately 18% of imatinib-treated patients experienced some form of disease progression, and 5% discontinued therapy because of adverse effects. “People have to remain on therapy and remain on it for the long term,” said Druker (http://www.medpagetoday.com, 5 June 2006).