LOS ANGELES — Researchers at the University of California Los Angeles said they have found a possible link between two new drugs for Type 2 diabetes and cancers of the pancreas and thyroid, according to a new study published in the journal Gastroenterology.
The researchers, at UCLA's Larry L. Hillblom Islet Research Center, examined incidents reported in the Food and Drug Administration's adverse event database between 2004 and 2009 among patients using Byetta (exenatide), made by Eli Lilly and Amylin Pharmaceuticals, and Merck's Januvia (sitagliptin).
"We undertook these studies because several studies in animal models by several investigators had suggested that this form of therapy may have unintended actions to promote growth of the ducts in the pancreatic gland that convey digestive juices from the pancreas to the gut," study co-author and Hillblom Center director Peter Butler said. "This is a concern if it happens in humans since it might be expected to increase the risk for pancreatitis and pancreatic cancer. While the FDA database has limitations, it does have advantages in being very large, openly accessible and independent from companies that market the drugs."
Both drugs work by stimulating the hormone glucagon-like peptide 1, or GLP-1. Previous research in rats has shown that enhancing the actions of GLP-1 may increase the rate of formation of cells that line the pancreatic ducts, which could lead to pancreatitis.
Comparing Januvia and Byetta with four others that constituted a control group, the researchers found a six-fold increase in the odds ratio for reported cases of pancreatitis, as well as a nearly threefold increase in the risk of pancreatic cancer. In addition, they found a statistically significant increase in the risk of thyroid cancer among patients taking Byetta, but not among those taking Januvia.