The study, presented at the annual meeting of the American Society of Hematology (ASH), suggests that patients should routinely receive the higher dose regimen if additional studies continue to show such a dramatic benefit for patients.
"This is a relatively small study, but there is no question that patients who used higher doses of Gleevec clearly showed improvement compared with patients who used a standard dose," says Jorge Cortes, M.D., deputy chair in the Department of Leukemia. "We feel so comfortable with what we are finding that patients being treated at M. D. Anderson already are being given the higher dose therapy."
The study is the first to look at use of high-dose Gleevec in patients with newly diagnosed, early stage CML. Initial dose-escalating studies conducted with CML patients who had failed traditional interferon treatment suggested that patients treated with higher doses of the drug did well, even though a 400-milligram dose was "arbitrarily" selected as the standard, Cortes says.
The researchers compared results of two ongoing consecutive trials being conducted at M. D. Anderson, one using standard dose Gleevec, and the other testing the higher dose in newly diagnosed patients. They found that 18 months after treatment, 28 percent of 114 patients treated with 800 milligrams of Gleevec a day (using two 400 mg pills) had no molecular evidence of disease, compared with 7 percent of 50 patients who used the 400 mg daily dose.
The benefit increased over time. After 24 months, 48 percent of patients using two daily pills had no evidence of disease, compared to 17 percent of patients treated with one pill a day. Now 30 months into the studies, data are still being gathered.
In the group receiving the standard dose, four patients have progressed to advanced disease, but no patients using the higher dose have progressed, Cortes says.
Cortes notes that while some patients on higher doses had lower blood cell counts initially, there is no significant difference in drug tolerance between the two groups. "Overall, higher doses of the drug are very well tolerated," he says.
Contact: Julie A. Penne, 713-792-0655; jpenne@mdanderson.org
Laura Sussman, 713-792-0655; lsussman@mdanderson.org