Treatment with imatinib results in good overall survival (OS) in patients with chronic myeloid leukemia (CML), approaching a normal life expectancy, according to the long-term follow-up of the CML-IV study. Survival outcomes did not differ based on imatinib dose or other therapy included, or on the speed of response to treatment, and was instead influenced by disease biology and demographics.
The CML-IV study began in 2002, and was designed to determine whether treatment with imatinib could be optimized, and to confirm results of earlier studies. The 10-year survival analysis was presented by Ruediger Hehlmann, MD, of the University of Heidelberg in Germany, at the European Hematology Association 22nd Congress in Madrid (abstract S424).
Between 2002 and 2012, the trial enrolled 1,551 newly diagnosed CML patients in the chronic phase; of those, 1,536 were evaluable for this analysis. They were randomized into 5 study groups: 400 patients received imatinib 400 mg; 430 patients received imatinib plus interferon; 420 patients received imatinib 800 mg; and in 2 pilot groups that were discontinued, 158 received imatinib plus cytarabine and 128 received imatinib following interferon failure. Patients had a median age of 53 years, and 61% were male.
After a median observation period of 9.5 years, the 10-year OS rate for all patients in the study was 82%. The 10-year progression-free survival rate was 80%.
Though the time to response was faster with imatinib 800 mg, the 10-year OS rates did not differ significantly between the treatment groups. With imatinib 400 mg, the 10-year OS rate was 80%; with imatinib 800 mg, it was 79%. For the imatinib plus interferon, imatinib plus cytarabine, and imatinib after interferon failure groups, the 10-year OS rates were 84%, 84%, and 79%, respectively.
A multivariate analysis showed that no form of treatment optimization influenced survival outcomes. The analysis found that CML risk group, presence of comorbidities, certain chromosomal aberrations, smoking, and type of treatment center (academic vs other types) did, however, play a role in survival. Patients who reached response milestones at 3, 6, and 12 months had better survival, but this did not vary by treatment group.
Previous research has shown that other nontreatment-related factors can also influence survival in CML patients. For example, a study published in May showed that uninsured patients and Medicaid patients fare significantly worse than those with Medicare or private insurance.
In this study, the authors concluded that imatinib 400 mg provides a close-to-normal life expectancy. “Outcome of CML is currently more determined by disease biology and demographics than by treatment optimization,” they concluded.