Breakthrough Cancer Drug Gleevec Gets Heart Precaution

FDA move on drug label unlikely to dim enthusiasm for the medication, experts say

FRIDAY, Oct. 20, 2006 (HealthDay News) -- The breakthrough cancer drug Gleevec will now carry a new "precaution" on its label about possible severe congestive heart failure that might result from its use.

The announcement came Thursday from the U.S. Food and Drug Administration, the same day the drug's maker, Novartis, issued a letter to health-care professionals.

The labeling revision is unlikely to diminish Gleevec's wonder-drug status, experts said.

"You have to remember that people take this drug for what is usually otherwise a fatal condition," said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. "Clearly, the benefits of Gleevec for the particular disease it treats far outweigh the risks. What this basically means is that patients have to watch more carefully and be aware of the symptoms, but this does not rise to the level where one would say we should take the drug off the market."

In fact, Lichtenfeld pointed out, the FDA has asked only for a precaution, which is less severe than a warning when it comes to drug labels.

Gleevec (generic name imatinib) is approved to treat chronic myelogenous leukemia -- CML -- and gastrointestinal stromal tumors.

On the same day the FDA was strenghtening the wording on Gleevec's label, Novartis issued a statement saying the FDA had approved the expanded use of Gleevec for the treatment of five rare, life-threatening disorders. This brings the number of diseases that Gleevec is approved to treat to seven, the company said in a news release.

Gleevec may now also be prescribed to treat the solid tumor cancer dermatofibrosarcoma protuberans, as well as four blood diseases: relapsed/refractory Philadelphia chromosome-positive acute lymphoblastic leukemia; myelodysplastic/myeloproliferative diseases; hypereosinophilic syndrome/chronic eosinophilic leukemia; and aggressive systemic mastocytosis, the company said.

The findings of a study reported at this year's meeting of the American Society of Clinical Oncology reported that overall survival for people with CML who took Gleevec for five years was 89 percent -- and 95 percent if only deaths related to CML were considered. At the same time, 93 percent of the cases still had not progressed from the chronic to the "blast crisis" -- or acute phase -- of the illness.

The label move comes four months after an article in the journal Nature Medicine reported that Gleevec might be toxic to the heart and lead to heart failure. The small study detailed how Gleevec inadvertently targets a protein maintaining cells that contract the heart muscle and help to force blood through the body. This means that other drugs in the same class, tyrosine kinase inhibitors, may also damage the heart, Lichtenfeld explained.

"The reality is that they, too, because of the particular way Gleevec causes heart failure problems, are suspect," he said.

The study followed up on 10 patients who developed severe heart failure after taking Gleevec. Those cases were first reported in 2004 by researchers at the University of Texas M.D. Anderson Cancer Center, in Houston.

According to a letter issued by Novartis and directed to health-care professionals, most of the affected patients had preexisting conditions such as high blood pressure, diabetes and coronary artery disease.

"The incidence of congestive failure is very small, and many of the patients had other illnesses," Lichtenfeld confirmed.

The letter maintained that "cardiac events remain uncommon," although "severe congestive heart failure and left ventricular dysfunction have occasionally been reported."

Patients with known cardiac disease or risk factors for cardiac failure should be monitored carefully, Novartis stated.

"The only thing this changes is the discussion that you have with the patient when you're talking about starting the medication, and it might also change how you monitor the patient," said Dr. Jonathan Goldberg, a hematology oncologist at Northern Westchester Hospital in Mt. Kisco, N.Y. "This medicine works so well for patients with CML that, even though there might be this small risk of heart failure, the benefits still greatly outweigh that risk."

Another expert agreed.

"The perception of CML has changed very dramatically in the eyes of the patient and in the eyes of the public," said Dr. Michael Deininger, an assistant professor at the Center for Hematologic Malignancies at Oregon Health & Science University. "What used to be a deadly disease is now perceived as a chronic ailment and people sometimes forget that if we don't treat CML, you're going to die from it. Even if there was a significant incidence of heart failure, on balance, weighing the advantages and disadvantages, there would still be a huge, huge advantage for Gleevec."

The Nature Medicine study also had some limitations, Deininger pointed out. There were no strong comparisons of heart function pre- and post-treatment. "The study is a little weak, to put it lightly, in terms of describing the patients," he said.

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