Study Shows the Drug Is a Successful Therapy for Chronic Myelogenous Leukemia
By Salynn Boyles
WebMD Health News
Reviewed by Laura J. Martin, MD
March 22, 2011 -- When Jerry Mayfield was diagnosed with leukemia in 1999 his doctors gave him about three years to live. Twelve years later, Mayfield says he feels just fine.
What makes his survival story so remarkable is that it is not remarkable at all.
Now new research confirms that the drug has transformed a previously fatal leukemia into a manageable chronic disease for many patients who take it.
Life Expectancy Improves
CML patients taking Gleevec (imatinib) were followed for up to eight years. In order to be enrolled in the study, patients needed to be incomplete remission after two years of starting the drug, and the study confirmed that they could expect to live as long as people without cancer.
Gleevec and two second-generation CML drugs that came after it are success stories in targeted cancer therapy.
Before Gleevec's introduction a decade ago, fewer than half of patients with CML survived for more than seven years and the main drug treatment -- interferon -- left most people feeling miserable with fatigue and persistent flu-like symptoms.
Most patients who take Gleevec respond well to treatment and the new research confirmed that serious side effects are uncommon.
"This is the first study to show that a cancer that cannot be cured by surgery can be controlled to the point that patients have a normal life expectancy," study researcher Carlo Gambacorti-Passerini, MD, of Italy's University of Milano Bicocca tells WebMD. "This is quite remarkable."
Checking for Adverse Events
The 832 patients in the study were followed for an average of about five years.
Twenty deaths occurred during follow-up, for a death rate of 4.8%. This was similar to the death rate that would be expected among people of the same age in the general population, Gambacorti-Passerini says.
Serious adverse events, including cardiovascular and digestive system problems, were reported in 139 patients, but only 27 cases were considered possibly related to Gleevec treatment.
The research was funded by Italy's drug safety agency and it included patients treated in academic and research centers and community-based hospitals.
The study is published online in the Journal of the National Cancer Institute.
Why Does Gleevec Work So Well?
While other targeted drug treatments are being used for other cancers, they have not proven to be game changers like Gleevec and two other targeted CML drugs: Tasigna (nilotinib) and Sprycel (dasatinib).
Johns Hopkins University associate professor of oncology B. Douglas Smith, MD, says this is not surprising.
"CML is a pretty simple cancer and we know a lot about it," he tells WebMD.
Patients with CML have a specific genetic abnormality that causes the disease. Gleevec and the other targeted treatments work by blocking the cancer-promoting enzyme created by this abnormality.
"Most cancers have multiple genetic hits, so it is not surprising that a single drug targeting one thing would not be as effective," he says.
In an editorial published with the study, Smith writes that confirming the long-term safety and effectiveness of targeted drug treatments for CML should spur research to find a cure for the disease.
Patients must stay on the targeted drugs for the rest of their lives and treatment with Gleevec can cost anywhere from $30,000 to $100,000 a year.
"We now know that patients do very well on these drugs, so we need to build on this success and look for ways to add to these therapies to achieve a cure," he says.
Gina Russo, of the Leukemia Lymphoma Society, says she is optimistic that targeted treatments will prove useful for more and more cancers.
"This is a model for the treatment of other blood cancers and solid tumors," she tells WebMD.
While Jerry Mayfield believes he would not be alive without Gleevec, he is among the minority of patients to develop resistance to the drug.
After about three years on the targeted therapy it stopped working for him. He joined an experimental trial for the now-approved second-generation drug Sprycel in 2004 and is now responding well to the third-generation experimental drug ponatinib, being developed by ARIAD Pharmaceuticals of Cambridge, Mass.
Now age 62, Mayfield is retired, living in Bloomington, Ill.
"I've certainly been at the right place at the right time and with a little luck and a little research and a little persistence, I'm still here and I'm still kicking," he says.
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