Rat studies suggest Victoza could spur rare thyroid tumor, but experts say effects in humans are unclear
THURSDAY, Feb. 18 (HealthDay News) -- The U.S. Food and Drug Administration is defending its decision in late January to approve a new diabetes drug, Victoza (liraglutide), even though animal studies suggest it might increase the risk for a rare thyroid cancer.
Victoza, among a class of medicines called glucagon-like peptide-1 (GLP-1) receptor agonists, is meant to be used along with diet and exercise to control blood sugar by helping the pancreas make more insulin after a person eats.
FDA officials explained the agency's stance on the drug in a Perspective article published online Feb. 17 in the New England Journal of Medicine.
"The relevance of the animal findings to people is unknown," said FDA spokeswoman Dr. Karen Mahoney. "The type of tumor of concern in people is medullary thyroid cancer, which is a very rare tumor that one cannot expect to be detected in a clinical trial."
No one treated with Victoza in the clinical trial that led to the drug's approval developed this type of cancer, she noted.
However, studies in rats showed that some animals treated with Victoza did develop thyroid tumors. "Some of these tumors were cancerous," Mahoney said. "In rats, cancers were also observed in untreated animals."
The cancer finding in treated rats, compared with the untreated group, was not considered significantly different, statistically, except among male rats that received an eight-fold higher drug exposure than what humans would receive at even the maximum proposed dose, Mahoney said.
"The life span of the animals in these two studies was not affected by liraglutide treatment," she added.
The drug also carries a slight increased risk of pancreatitis, which is not uncommon in diabetics. A common side effect of Victoza is nausea and vomiting, which can
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