ATLANTA—Six-year results of the IRIS trial confirm imatinib(Drug information on imatinib) (Gleevec) as the standard first-line therapy for chronic myelogenous leukemia, Andreas Hochhaus, MD, professor of internal medicine, the University of Heidelberg, Mannheim, Germany, said at ASH 2007 (abstract 25).

Overall survival at 6 years for patients receiving imatinib therapy was 88%. Dr. Hochhaus noted that if only CML-related deaths were taken into account, the estimated overall survival rate with imatinib was 95%.

"If this survival trend continues, many patients with CML may approach normal life expectancy with continued Gleevec treatment," said Brian Druker, MD, director of the of the Oregon Health & Science University Cancer Institute.

IRIS, launched in 2000, compared standard treatment with interferon-alfa plus cytarabine(Drug information on cytarabine) against imatinib in 1,106 patients with newly diagnosed Ph+ CML. Eventually, 66% of controls crossed over to imatinib, while only 2% on imatinib crossed over to interferon-alfa plus cytarabine. After 6 years, 181 patients had discontinued study treatment.

Event-free survival

At 6 years, event-free survival (EFS) for the imatinib patients was 83%, and progression-free survival—survival without CML progression to accelerated or blast phase—was 93%.

Dr. Hochhaus pointed out that annual event rates—ie, loss of complete hematologic or major cytogenetic response, progression, or death—have declined over the course of imatinib treatment, from a high of 7.5% in the second year of treatment to 0.8% in the 5th year and 0.4% in the 6th year.

Annual event rates for those achieving complete cytogenetic response (CCyR) declined from 5.4% in the 1st year to 0.3% in the 4th year, with no conversions to accelerated phase/blast crisis after the 3rd year.