Despite other drugs in the same class being linked to thyroid cancer, Onglyza still yields ample sales for its manufacturer AstraZeneca.

Onglyza is AstraZeneca’s brand name for a relatively new diabetes medication known generically as saxagliptin.

It was first approved for sale in the United States in 2009. Since it works by increasing the level of insulin in the blood, Onglyza is approved to treat type-2 diabetes but not type-1.

The same active ingredient is also used in the drug Kombiglyze XR, a combination of saxagliptin and the older diabetes medication metformin.

Saxagliptin is part of a class of medications known as incretin mimetics. These medications imitate the action of incretins, the hormones that the body releases after eating a meal to stimulate the release of insulin. By increasing the level of insulin in the blood, incretin mimetics lower the level of sugar in the blood.

At the same time, incretin mimetics also inhibit the liver from releasing more glucose into the blood by suppressing production of the hormone glucagon. Suppression of glucagon may account for as much as 50 percent of the effect of incretins.

Incretin mimetics can offer at least one advantage over the naturally-occurring hormones they mimic. These hormones tend to be readily broken down in the body by an enzyme known as DPP-4.

Some incretin mimetics are made to function like incretin hormones without being broken down by DPP-4. Others are designed to work by inhibiting the action of DPP-4, leaving more naturally-occurring incretins in the blood.

Onglyza and Thyroid Cancer

Unfortunately, other diabetes medications in the same class as Onglyza have been associated with thyroid cancer. In 2009, the FDA released a Risk Evaluation and Mitigation Strategy for another incretin mimetic known as Byetta, in part “to explore a potential signal of a serious risk of thyroid cancer.”

Another incretin mimetic named Victoza was the subject of a June 2011 FDA safety alert, warning doctors and patients that the medication had been linked to the development of thyroid tumors in rats and mice.

More recently, in a review published in the Journal of Environmental Science and Health Part C Environmental Carcinogenesis & Ecotoxicology Reviews in 2015, researchers reviewed available literature addressing the link between incretin mimetics and different types of cancer.

In reports made to the FDA’s Adverse Events Reporting System, the researchers found “significantly higher risk of thyroid cancer” associated with a subset of incretin mimetics known as GLP-1R agonists.

Despite the potential risks, Onglyza has been popular as a diabetes medication. Unlike other diabetes medications, Onglyza helps control blood sugar levels without promoting weight gain. In fact, many users of incretin mimetic diabetes medications have reported actually losing weight while using these drugs.

Onglyza’s popularity has translated to ample sales for manufacturer AstraZeneca. Sales of Onglyza reached as high as $820 million in 2014. By 2018, at least one projection predicts Onglyza sales could exceed $2.4 billion.

Incretin mimetics like Onglyza are a relatively new group of drugs, and their side effects are still being investigated. In addition to thyroid cancer, some of these drugs have also been linked to conditions like pancreatitis, pancreatic cancer, and heart failure.