Side Effects of Saxenda, Victoza May Increase Colon Cancer Risks: Study

The findings of a new study suggest that a class of diabetes and weight loss drugs, which includes Victoza, Byetta and Saxenda, may increase the risk of colon cancer. In addition, the cancer risks may be heightened among patients who have undergone bariatric surgery, the researchers warn. 

Canadian researchers report that a class of drugs known as glucagon-like peptide-1 (GLP-1) receptor agonists may increase cell division in the gut, increasing the risks of colon cancer. The findings indicate that GLP-1 receptors play a key role in mucosal expansion in the small bowel (SB) and colon.

The study was published by the medical journal Cell Metabolism on March 3, involving tests on mice, and comes amid increasing concerns over the side effects of Victoza and Byetta. A new weight loss drug, Saxenda, which also uses the same active ingredient as Victoza, may also carry the same side effects.

“Although pharmacological administration of GLP-1R agonists increased the mass of SB epithelium, mechanisms connecting GLP-1R activation to intestinal growth were not identified,” the researchers noted.

The researchers raised concerns about the use of weight loss drugs like Saxenda in combination with bariatric surgery.

“Although weight loss and bariatric surgery are generally associated with reduced rates of cancer, increased rates of colorectal cell proliferation and crypt fission have been detected in rectal mucosal biopsies from obese subjects as long as 3 years after bariatric surgery. Furthermore, a large nationwide retrospective cohort study of 15,905 obese subjects treated with bariatric surgery revealed a significantly increased incidence of colorectal cancer, relative to obese control subjects,” the researchers noted. “Moreover, the incidence rate for development of colorectal cancer progressively increased with length of time after bariatric surgery. However, the importance and mechanistic underpinning of these findings remains unclear and will require additional investigation.”

Byetta and Victoza Health Concerns

Byetta and Victoza are injectable drugs that are part of a wider class of diabetes medications known as incretin mimetics, which also includes the blockbuster drugs Januvia and Janumet, which are oral medications. The drugs work by mimicking the incretin hormones the body usually produces to naturally stimulate the release of insulin in response to a meal.

Byetta (exenatide) was the first member of the incretin mimetic class approved by the FDA, introduced by Amylin Pharmaceuticals in 2005 as a twice daily injection. Victoza (liraglutide) is a similar injectable diabetes drug introduced by Novo Nordisk in 2010 as a longer-acting daily injection.

Side effects of Byetta and other incretin mimetics have previously been linked to a risk of severe pancreatitis, which some reports suggest may lead to the development of pancreatic cancer for some users.

In the federal court system, nearly 600 Byetta lawsuits, Victoza lawsuits, Januvia lawsuits and Janumet lawsuits are filed on behalf of individuals nationwide diagnosed with pancreatic cancer after using the medications are consolidated as part of an incretin mimetic diabetes drug litigation, which is centralized for pretrial proceedings before U.S. District Judge Anthony Battaglia in the Southern District of California as part of an MDL, or multidistrict litigation.

As part of the coordinated pretrial proceedings before Judge Battaglia, it is expected that a series of early trial dates will be scheduled in the MDL involving each of the different medications, to help gauge how juries may respond to certain evidence and testimony that is likely to be repeated throughout the litigation. While the outcomes are not binding in other cases, it may help the parties reach additional agreements to settle Byetta and Victoza cases.