Another measure of successful treatment is the number of patients with complete molecular response, occurring when the levels of BCR-ABL are so low that they are undetectable using a highly sensitive method called polymerase chain reaction. In past studies, patients who had undetectable levels of BCR-ABL after treatment have not relapsed after long-term follow up. In high-dose therapy patients, the incidence of complete molecular response was 28 percent compared to only seven percent of patients taking the standard dosage of imatinib.
"The high rates of complete cytogenetic and molecular response that we've seen in this study are unprecedented. If such responses have similar long-term significance as seen in previous studies, this translates into a major improvement in the prognosis of patients with CML," states Hagop Kantarjian, M.D., chairman of the Department of Leukemia at M. D. Anderson Cancer Center and the lead author of the study.
Researchers found that the high dosage of imatinib was generally well tolerated, with a similar rate of side effects as standard dose imatinib. To reduce more severe side effects, the dosage of imatinib was lowered to 600 mg or 400 mg daily for some patients, though a majority remained at the target dosage.
The disease did not transform beyond the chronic phrase in any of the study patients, and 98 percent had a complete hematologic response, meaning the number of white blood cells was no longer out of control and the signs and symptoms of leukemia were gone.
The results of the study indicate that patients in the early stage of this cancer may benefit from higher doses of the drug imatinib in their initial treatment to safely and effe
Contact: Aislinn Raedy
American Society of Hematology