New Study Underscores Increased Dangers of Certain Diabetes Treatments

The brilliantly designed and carried out study by Drs. Alexandra Butler and Peter Butler of the University of California-Los Angeles (UCLA), and their colleagues at UCLA and the University of Florida, published today online in the journal "Diabetes," provides evidence of increased precancerous changes such as dysplasia in the pancreata (pancreases) of diabetic patients using GLP-1-mimicking (incretin) diabetes drugs such as Byetta (exenatide), Victoza (liraglutide) and Januvia (sitagliptin), compared to pancreata from diabetics not using these drugs or those from non-diabetics.

These findings are in accord with the rapidly increasing number of reports to the U.S. Food and Drug Administration (FDA) of pancreatic cancer in patients using these drugs compared with diabetics using other drugs for diabetes.

In the two and a half years between January 1, 2010, and June 30, 2012, according to IMS prescribing data from the U.S., more than 35 million prescriptions were filled for one of the most commonly prescribed diabetes drugs, glipizide. The sum of prescriptions for the three most commonly prescribed incretin drugs, Byetta, Victoza and Januvia, during this same time interval was 33 million prescriptions.

We looked at reports in the FDA's electronic adverse reaction database (AERS) of pancreatic tumors, almost all being cancer of the pancreas, in patients in whom these three drugs were listed as the primary suspect drug for the tumors. There were a total of 292 reports of pancreatic tumors between January 1, 2010, and June 30, 2012, for these three incretin drugs, but only one report for glipizide, an older diabetes drug not in this family. For some of the drugs, especially Victoza, these reports came from other countries as well as the U.S.

For a large number of these reports, incidents to the FDA in 2010 or 2011, we examined the full MedWatch forms containing details of each reported cancer case, which we obtained by a Freedom of Information request to the FDA. In the vast majority of these cases, the narrative for each case did not list any other possible causes of pancreatic cancers such as a history of heavy alcohol intake or smoking.

During the last six months for which AERS data are available, there was a substantial increase in reports of pancreatic cancer for these three drugs, out of proportion to the increase in U.S. prescribing for the drugs during that interval.

Although we have previously petitioned the FDA to ban Victoza (liraglutide) because of concerns about pancreatic disease and thyroid cancer, it is clear that all of the drugs in this family are associated with an increased risk of pancreatic cancer and it is likely that they will all have to be removed from the market. The idea of putting a warning label about pancreatic cancer on drugs that have no unique benefit for diabetics but which have increasing evidence of the risk for pancreatic cancer--instead of banning the drugs altogether--would be an extraordinarily reckless approach for the FDA to initiate.