The scene at the European Association for the Study of Diabetes being held in Lisbon this week has included a heated debate over the extent to which a particular type of diabetes medicine called GLP-1 therapies can increase the risk of pancreatic and thyroid cancer. These include Byetta, which is sold by Eli Lilly and its partner, Amylin Pharmaceuticals, and Victoza, which is marketed by Novo Nordisk.
The issue has actually been percolating for more than a year (read here), although a review published two months ago in Gastroenterology that reviewed the FDA database of side effects showed patients taking Byetta had a much larger chance of developing pancreatitis, which can increase the risk of tumors (read the abstract). The drugmakers maintain their meds are safe.
And so there was a debate among researchers in attendance, including Peter Butler of the University of California at Los Angeles, who was one of the authors of the Gasterenterology study. One of his opponents was Michael Nauck, head of the Diabeteszentrum Bad Lauterberg in Germany, who told Bloomberg News that "the bulk of findings tends to speak against such an association. There is no general agreement.”
In fact, he believes the FDA database not only fails to establish a link to thyroid and pancreatic cancer, but may instead show the drugs could protect against other forms of cancer, such as prostate tumors. "Looking at same database and using very, very similar methods, I find evidence that some forms of cancer are reduced."
Similarly, Matteo Monami, a physician at the University of Florence and Carreggi Teaching Hospital in Italy, told Bloomberg that the Gasteroenterology study is “erroneous analysis” and its results “are really not reliable at all." He presented a study showing no increase in cancer or pancreatitis for so-called dipeptidyl peptidase-4 inhibitors such as Januvia. However, what was not made clear is that both Nauck and Monami have ties to the drugmakers that sell the GLP-1 treatments. For instance, Nauck has worked as a consultant to both Lilly and Novo Nordisk, and also received clinical research grants from both drugmakers (look here). And Monami has received speaking fees from Lilly (see this).
Of course, it does not automatically follow that one or both researchers is biased due to their relationships with either drugmaker. Just the same, such ties would have been helpful to know, given that they were rather outspoken in defending the medications at an important meeting where the scientific community gathers to absorb and ponder research that is used to influence medical practice.