Reworked Gleevec curbs heart-related complication
By Will Dunham
WASHINGTON (Reuters) - A redesigned version of Novartis AG's cancer drug Gleevec may avoid a rare heart-related side effect while more specifically targeting a type of stomach cancer, researchers said on Monday.
The researchers said their work was important in showing that extremely minor changes can be engineered into drugs to eliminate potentially dangerous side effects while leaving them effective against disease.
Known generically as imatinib and also sold as Glivec, the once-a-day pill is the Swiss drug maker's second-biggest seller, with sales of $2.6 billion last year.
Gleevec, which has been on the market since 2001, is used to treat some forms of leukemia, cancer that arises in the white blood cells, and other cancers of the blood cells. Gleevec is also used to treat a rare type of stomach cancer called gastrointestinal stromal tumor, or GIST.
Researchers at Rice University in Houston and University of Texas M.D. Anderson Cancer Center said they re-engineered the drug to curb a life-threatening side effect in which the drug can be toxic to the heart and potentially cause heart failure.
The re-engineered version appears to be just as effective as Gleevec in treating GIST while posing a significantly lower risk of heart failure, they said.
As the researchers expected, the re-engineered version does not work against leukemia, they reported in the Journal of Clinical Investigation.
Ariel Fernandez, a Rice bioengineering professor who worked on the research with M.D. Anderson's Gabriel Lopez-Berestein and others, said the redesigned drug is the same as Gleevec except that four atoms -- a carbon and three hydrogen atoms -- have been added at a key point.
"The interest of this goes way beyond this particular drug and this particular side effect. The idea is we could demonstrate for the first time that you can take a drug with side effects and re-engineer it to curb those side effects," Fernandez said in a telephone interview.
"Side effects are the graveyard of most drug-discovery endeavors. So once a drug is shown to have side effects or potentially could have side effects, the drug company doesn't want to have anything to do with it," Fernandez added.
Novartis had no role in the research, Fernandez said.
The researchers said they tested the redesigned drug in mice, in human cancer cells in laboratory dishes and in computer models.
The precise incidence of heart failure in patients taking Gleevec is not known but is thought to be low, the researchers said. A look at leukemia patients taking Gleevec at M.D. Anderson indicated that about 2 percent experienced symptoms that might have been linked to heart failure, they said.
The American Cancer Society said gastrointestinal stromal tumors are not common, but the precise number of people diagnosed with GIST each year is not known. It cited estimates of 4,500 to 6,000 cases each year in the United States.
The tumors most often occur in the stomach, but also may occur in the small intestine and elsewhere in the gastrointestinal tract, the American Cancer Society said.
(Editing by Maggie Fox and Cynthia Osterman)