Study Sees No Evidence Linking Diabetes Drugs With Pancreatic Cancer
But FDA assessment calls for further look at injectable type-2 treatments
WEDNESDAY, Feb. 26, 2014 (HealthDay News) -- There's no firm evidence that the type 2 diabetes medications known as incretin-based drugs cause pancreatitis or pancreatic cancer, U.S. and European health officials say.
But it's too early to say there's definitely no link between the injectable drugs and pancreatitis or pancreatic cancer, according to the safety assessment by the U.S. Food and Drug Administration (FDA) and its counterpart overseas, the European Medicines Agency (EMA).
"Both agencies agree that assertions concerning a causal association between incretin-based drugs and pancreatitis or pancreatic cancer, as expressed recently in the scientific literature and in the media, are inconsistent with the current data," states the report in the Feb. 27 issue of the New England Journal of Medicine. "The FDA and the EMA have not reached a final conclusion at this time regarding such a causal relationship."
Incretin-based drugs are among the newest medications available to treat type 2 diabetes, a chronic condition characterized by high levels of sugar in the blood. Nearly 26 million people in the United States and 33 million in the European Union have diabetes, and type 2 is by far the most common type.
There are two types of incretin-based medications: GLP-1 agonists and DPP-4 inhibitors.
Examples of GLP-1 agonists include exenatide (Byetta) and liraglutide (Victoza). Exenatide, the first incretin-based drug approved by the FDA, was approved in 2005.
Examples of DPP-4 inhibitors include sitagliptin (Januvia) and saxagliptin (Onglyza). Sitagliptin was the first DPP-4 inhibitor approved by the FDA, receiving consent in 2006.
GLP-1 agonists slow stomach emptying and increase insulin secretion, which help keep blood sugar lower. They also suppress secretion of a hormone that raises blood sugar levels.
DPP-4 inhibitors slow the absorption of carbohydrates through the stomach, help increase insulin levels and suppress the blood-sugar elevating hormone, said Dr. Robert Ratner, chief scientific and medical officer at the American Diabetes Association.
One of the challenges in diabetes control is keeping blood sugar levels low while avoiding hypoglycemia, or dangerously low blood sugar. "The clinical data suggests these are very [effective] drugs that don't cause hypoglycemia," said Ratner.
Also, unlike some diabetes drugs that promote harmful weight gain, GLP-1 agonists cause weight loss, while DPP-4 inhibitors are weight neutral. Weight loss often improves diabetes.
After the drugs received approval, the FDA and EMA received reports of pancreatitis (inflammation of the pancreas) and pancreatic cancer in people taking the drugs.
"There was a disproportionate reporting of these adverse events detected," said the lead author of the safety assessment, Dr. Amy Egan, deputy director for safety in the FDA's division of metabolism and endocrinology products.
However, the risks of pancreatitis and pancreatic cancer are already elevated in people with type 2 diabetes, said Egan. In addition, because they can aid weight loss, GLP-1 agonists are often prescribed to heavier people. Obesity is also a known risk factor for pancreatitis disease, Egan noted.
Because these and other factors can confound findings of an association in people taking the drugs, the FDA and EMA conducted extensive reviews of the available data from animals. The FDA reviewed 250 toxicology studies conducted in nearly 18,000 healthy animals. The EMA conducted a similar review. Neither agency found an increased risk of pancreatitis related to incretin-based drugs.
And neither agency found any drug-induced pancreatic tumors in rats and mice treated for two years (their adult life span) with the drugs.
Both agencies also reviewed data from hundreds of trials in humans and found no convincing link. Two large clinical trials are currently underway, and experts hope they will provide a more definitive answer.
So what's a person taking these medications supposed to do in the meantime?
"In June, the American Diabetes Association, the European Association for the Study of Diabetes and the International Diabetes Federation released a statement recommending that no patient should discontinue their medication without consulting their doctor first. And patients taking these medications should be informed of all the possible risks and benefits so they can make the best decision for themselves," said Ratner.
The FDA and EMA have further validated that position, Ratner said. "We need to continue to be vigilant, but as of now, there doesn't seem to be any reason to change our approach," he noted.
The FDA concluded that the current labeling for these drugs contains the necessary information and isn't recommending any labeling changes at this point.
Learn more about incretin-based medications from the University of California, San Francisco.