- The Washington Times - Sunday, July 23, 2006

ASSOCIATED PRESS

A successful cancer-fighting drug also may damage the heart, although a researcher says leukemia patients who need Gleevec should not abandon it.

Although it effectively treats cancer, Gleevec can lead to heart failure in some patients, said Dr. Thomas Force, who teaches medicine at Jefferson Medical College of Thomas Jefferson University in Philadelphia.

His study, published yesterday in the online edition of the journal Nature Medicine, was prompted by reports that 10 patients taking Gleevec for chronic myelogenous leukemia developed severe congestive heart failure.

Gleevec, sold under the name Glivec in some countries, had worldwide sales of $1.2 billion in the first six months of this year, according to the manufacturer, Novartis Pharmaceuticals Corp.

“Gleevec is a wonderful drug, and patients with these diseases need to be on it. It’s a lifesaving drug for sure,” Dr. Force said.

“This is not a Vioxx situation,” he added, referring to Merck & Co. Inc.’s painkiller that was pulled from the market because of heart side effects.

Dr. Force said he is trying to call attention to the fact that Gleevec and other similar drugs in development could have significant effects on the heart, and that doctors need to be aware of this and watch for symptoms.

Novartis said that the data was limited and that further research was needed to better the relationship between the drug and side effects.

The company said the prescribing information with the drug includes data on heart problems. In addition, the drug maker said clinical trials and postmarketing safety data have shown that the incidence of heart failures among people taking the drug is “extremely rare.”

Novartis said Dr. Force’s work does not change “the positive benefit/risk ratio of Glivec for thousands of patients being treated for cancer and other life-threatening diseases.”

Dr. Force said the 10 patients with heart failure were taking Gleevec at the University of Texas’ M.D. Anderson Cancer Center in Houston and had no heart problems before going on the drug.

He said doctors took base line measures of the patients’ left ventricular heart function and determined that heart failure developed in these patients two months to 14 months after they began taking Gleevec.

Gleevec targets three proteins, including one called ABL.

In chronic myelogenous leukemia, genes known as ABL and BCR become fused and produce a hybrid BCR-ABL enzyme that is always active. The overactive BCR-ABL, in turn, drives the excessive proliferation of white blood cells that is the hallmark of leukemia.

Using viruses that were produced for normal ABL and a Gleevec-resistant mutant in laboratory studies and in mice, the researchers found that Gleevec inhibited the normal enzyme but not the mutant, and the mutant ABL “rescued” heart cells from the toxic effects of Gleevec.

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