Possible Link Indicated Between Two Diabetes Drugs and Pancreatic Cancer

According to a recent study by UCLA researchers, two drugs which treat type 2 diabetes could lead to a substantially increased risk of pancreatitis and pancreatic cancer; one drug may even be linked to a further increased risk of thyroid cancer.

The two drugs—sitagliptin and exenatide—are known to increase of the gut hormone glucagon-like peptide 1 (GLP-1) which has been shown to successfully decrease blood sugar in diabetic individuals. This ability to increase GLP-1, however, is the possible link to pancreatitis in patients who take these medications.

A previous study (published in 2009) was performed on rats by researchers from the UCLA Hillblom Center, and it indicated that this connection may be due to a rise in the rate of formation of cells which border the pancreatic ducts.

Co-author of this current study, Peter Butler, director of the Hillblom Center, reported that he and his fellow researchers "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 (tubes) in the pancreatic gland that convey digestive juices from the pancreas to the gut.”

"This is a concern if it happens in humans since it might be expected to increase the risk for pancreatitis and pancreatic cancer,” continued Butler.

The researchers assessed databases from the US Food and Drug Administration (FDA) for reports of adverse events from patients using sitagliptin and exenatide between the years of 2004 and 2009.

Upon examination of these records, the researchers discovered a six-fold increase in the odds ratio for reported cases of pancreatitis with patients taking these drugs, in comparison with four separate control diabetes treatments.

Further, patients who were prescribed the two drugs were more likely to suffer from pancreatic cancer than patients who were treated with the other therapies.

The researchers also discovered, in comparison to other therapies, a 2.9-fold and 2.7-fold increased rate of pancreatic cancer in patients using exenatide and sitagliptin, respectively.

An interesting find, they added, was a statistically noteworthy boost in the risk of thyroid cancer in patients who took exenatide, but not among patients on sitagliptin.

There was no other link found between the two drugs and any other forms of cancer.

These findings are very significant, but the researchers acknowledged that assessing the database used in this study was not the same thing as studying living participants. They stated that the FDA's database "is not the ideal mechanism to compare adverse event rates between drugs.”

"Randomized, controlled clinical trials remain the gold standard for such assessment," wrote the researchers.

Still, Butler said that “while the FDA database has limitations, it does have advantages in being very large, openly accessible and independent from companies that market the drugs.”

"Taken together,” continued Butler, “the animal studies and the FDA database analysis suggest that further work needs to be undertaken to at least rule out that this now widely available new drug class for diabetes does not increase the risk of pancreatic cancer."

The study is published in the journal Gastroenterology.