In 1999, the medical world learned that a new drug, imatinib, sold as Gleevec, was remarkably effective at treating patients with chronic myelogenous leukemia, or CML. But at that time doctors didn't know if the drug would help people with this disease live longer.

Now researchers from M.D. Anderson Cancer Center in Houston report that Gleevec does prolong the lives of people with CML. Their study appeared in the journal Cancer (Vol. 98, No: 12: 2636-2642).

CML Fatal Within a Few Years

The word "chronic" in the name of this disease is deceptive. At one time, half of people with chronic myelogenous leukemia died within 3 to 4 years of diagnosis. Treatment with interferon, introduced in the 1980s, prolonged survival to about 7 years. But injections of interferon carry major side effects, and 7 years is a short time for a disease where one-third of patients are younger than 55.

The only "curative" treatment was stem cell transplantation using blood-forming cells from a donor. Although it was often effective, this very toxic therapy led to immediate death in at least 10% of patients, as well as many long-term serious side effects. Moreover, only patients younger than 50 were eligible for treatment.

To learn whether Gleevec would prolong life better than did interferon, the M.D. Anderson researchers compared 187 CML patients given imatinib with 650 similar patients who received interferon. The interferon patients were treated in the 1980s and early- to mid-1990s, while the Gleevec patients began receiving their treatment in the late 1990s.

Gleevec Better Than Interferon

After 3 years of treatment, around 98% of patients treated with Gleevec were still alive. Comparatively, only 80%-85% of interferon patients treated in the past had survived 3 years.

The Gleevec patients also reported feeling better, probably because they didn't suffer side effects of interferon, such as severe fatigue and depression. In an earlier study of interferon compared to Gleevec, most patients eventually refused interferon treatment so they could switch to the Gleevec.

The medical world generally frowns on historical studies like this one. Factors other than the new drug could have led to the better survival. For example, people in the more recent group might have lived longer because of better supportive care, such as newer antibiotics and better understanding of the disease.

But supportive care hasn't improved that much in the past decade or two. And because Gleevec is so effective and the alternate therapy so toxic, the M.D. Anderson researchers make the point that it is highly unlikely that the "gold standard" study, a head-to-head comparison of the two, could ever be done.

The researchers conclude, "The results of the current study indicate that imatinib (Gleevec) has a significant survival benefit versus the historical data with interferon and, therefore, has favorably changed the prognosis for patients with chronic myelogenous leukemia."

For additional information, please contact:
Keith Muhleman, CR&T.
Phone: 212-288-6604
Fax: 212-288-7704 or 212-746-8246
e-mail: kmuhleman@crt.org