Manufacturers of a class of type 2 diabetes drugs known as incretin mimetics may be covering up data that suggests the medication may cause pancreatic cancer, a British Medical Journal/Channel 4 investigation reveals.
This year alone three different studies have questioned the safety of the drugs. First, in February, researchers at Johns Hopkins University found that patients taking the incretin mimetics Januvia (sitagliptin) and Byetta (exenatide), also known as GLP-1 drugs, were twice as likely to be hospitalized for acute pancreatitis than patients who took other classes of medication.
In April, an analysis of Food and Drug Administration (FDA) data revealed an increasing number of pancreatitis, pancreatic cancer and thyroid cancer among patients taking five different incretin mimetics drugs.
The third study, conducted by Peter Butler, chief of the division of endocrinology at the University of California, Los Angeles, involved the pancreases of people who had died of a non-pancreas-related disease. Butler found that the pancreases of those who had taken incretin mimetics were more likely to have precancerous abnormalities than those from diabetics who took other classes of type 2 diabetes medications.
Butler said he was prompted to do the study based on his own research five years earlier when he and UCLA colleagues discovered that rats who were treated with sitagliptin (Januvia) developed enlarged pancreases and cellular changes in their pancreas that could likely lead to cancer.
Makers of incretin mimetics are quick to punch holes in the data, claiming that the data does not confirm a casual relationship between Byetta and Januvia and pancreatitis or pancreatic cancer. However, investigators say they have reviewed thousands of pages of regulatory documents and found even more unpublished data revealing proliferative or inflammatory pancreatic effects.
They also found that, despite the published reports that show a safety issue with the drugs, the drug companies have yet to conduct critical safety studies. Further, access to raw data that would have helped resolve concerns about the drugs’ safety has been denied.
“All drug licensing is about balancing benefits and risks,” states British Medical Journal editor-in-chief Dr. Fiona Godlee in a press release that accompanies the investigative report. “But instead of engaging in open debate about legitimate and important scientific questions, the manufacturers have been unwilling to share their data … (and) patients and doctors have not been kept properly informed about the uncertainties surrounding these drugs.”