The FDA approved Glivec in May of 2001 after 11 weeks of consideration -- the fastest review in the administration's history -- setting the stage for its use on patients with advanced stage Philadelphia-chromosome-positive chronic myeloid leukemia. The treatment has been successful enough that doctors are continuing to recommend the treatment, even in the face of this recent study.
The study reported 10 people had died from congestive heart failure while on Glivec, without any other medical reason being found for the condition, and laboratory mice treated with Glivec developed heart pathology, according to the journal Nature Ivied.
Analyses of the hearts of both humans and mice treated with Glivec imply that the drug may be toxic to cardiac cells. The drug, set to pioneer "targeted therapies," was originally thought to only target the Ab1-Bcr fusion protein, the causal agent in chronic myelogenous leukaemia, but this was before scientists realized Ab1 helps maintain cardiac cell health.
"In addition to being very relevant to patients on Glivec, this raises concerns that with a host of these types of drugs in development that target tyrosine kinases, there may be more such 'surprises,'" said researcher Thomas Force of the Jefferson Medical College in Philadelphia. Nevertheless, Force thinks the drug should be kept on the market and "should not be limited to a subset of patients."
"We are trying to alert cancer specialists that this is a problem that needs to be watched for," he said.
The benefit/risk ratio for Glivec is positive, according to the drug's marketer Novartis, which notes more than 100,000 patients currently take Glivec, and a clinical trial of more than 200,000 patient years has shown related heart failures are "extremely rare."
Researchers have said that more studies are needed to determine the magnitude of risk in taking Glivec, and all patients undergoing the treatment should be monitored for signs of heart failure.
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