Adapted from the NCI Cancer Bulletin.
In an international study, the risk of death for chronic myelogenous leukemia (CML) patients treated with imatinib (Gleevec) who had been in remission for at least 2 years was not different from that of the general population. The Imatinib Long-Term (Side) Effects (ILTE) study, led by Dr. Carlo Gambacorti-Passerini from the University of Milano-Bicocca in Italy, is the first independent assessment of imatinib’s long-term effects. The results were published online March 21, 2011 in the Journal of the National Cancer Institute.
The researchers enrolled 832 patients from 27 hospitals on five continents who were in remission after taking the drug for 2 years. The patients were followed for a median of almost 4 years from enrollment, corresponding to almost 6 years from the start of imatinib treatment. Only 27 patients experienced a major side effect associated with the drug during follow-up. More than half of patients experienced at least one mild side effect that affected quality of life, of which 68 percent were possibly or likely related to the drug. However, only 2.3 percent of patients discontinued treatment due to side effects.
At 6 years from the start of treatment, 95 percent of patients remained in remission. Of 20 observed deaths, only six were related to CML progression. “A comparison of the observed mortality rate in CML patients with the rate in the general Italian population showed no excess mortality,” the authors wrote.
The excellent survival of the patients in this study “speaks to both the astounding effect [imatinib] has had on the clinical course of this disease and its negligible effect on the development of treatment-related malignancies,” commented Dr. B. Douglas Smith of the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center in an accompanying editorial.
Dr. Smith noted that a large number of the patients (478) had received imatinib as second-line therapy, and 90 percent of those patients had previously received treatment with interferon. Further analysis of the data would be helpful to determine whether interferon played a role in the observed long-term remissions, suggested Dr. Smith.