Eli Lilly (NYSE:LLY) just unveiled new data showing that one of its diabetes drugs -- Tradjenta -- doesn't increase the risk of cardiovascular events, including heart attack and stroke. The results could help Tradjenta capture a greater share of the multibillion-dollar DPP-4 class of diabetes drugs, so let's learn more about it.

A little background

In healthy people, the body's pancreas produces insulin that stores or converts glucose, a simple sugar found in carbohydrates and produced in the liver, into energy. In type 1 diabetes, damage to insulin-producing cells in the pancreas prevents insulin production, and in type 2 diabetes, obesity and smoking contribute to patients developing a resistance to insulin, which makes it harder for insulin to control blood sugar levels. If left untreated, too much glucose in the blood can result in nerve damage, kidney damage, and life-threatening cardiovascular disease. 

To keep this from happening, patients may use a variety of treatments, including insulin injections and drugs that can increase insulin production or reduce glucose levels, including dipeptidyl peptidase-4 (DPP-4) inhibitors such as Tradjenta, which Eli Lilly comarkets with Boehringer Ingelheim.

DPP-4 is an enzyme that's tasked with destroying gastronintestinal hormones called incretins. In healthy people, the job of incretins is to decrease the natural production of glucose by the liver, while also signaling the pancreas to produce more insulin. Therefore, interfering with DPP-4's ability to break down incretins in type 2 patients reduces blood sugar levels in two ways -- by tamping down glucose production and boosting insulin production.

New data could help Tradjenta compete

Tradjenta has been on the market since 2011. However, it wasn't the first DPP-4 to reach the market, and it's not the only DPP-4 drug that doctors can prescribe currently.

Merck & Co.'s (NYSE:MRK) Januvia, which got the nod in 2006, holds the distinction of being the first DPP-4 inhibitor to win Food and Drug Administration (FDA) approval. The second DPP-4 to get an OK was Onglyza in 2009, the third was Tradjenta, and the fourth to secure a green light was Nesina in 2013. 

The ability of DPP-4 inhibitors to lower blood sugar levels has turned them into a blockbuster class of medicine, but Tradjenta's sales significantly trail that of the class leader, Januvia. In 2017, Boehringer Ingelheim reported Tradjenta global sales of about $1.5 billion at current exchange rates, while Merck & Co. has reported Januvia sales of $5.9 billion. Onglyza's sales were $611 million, and Nesina's sales were less than $50 million (at current exchange rates) in 2017.

Merck & Co.'s Januvia success has been helped by heart failure risks that have been observed in cardiovascular safety studies for Onglyza and Nesina. All three drugs carry warnings of heart failure risk on their labels. However, the absence of an increase in heart failure risk in Januvia's cardiovascular safety trial probably gives it an edge with prescribers over those other drugs.

Januvia's advantage over Tradjenta is likely to disappear, though, following the release of results from Tradjenta's cardiovascular safety study this week showing that Tradjenta doesn't increase the risk of cardiovascular events, either.

Impact on investors

Tradjenta's trial included more patients with kidney disease than studies evaluating cardiovascular safety for competing DPP-4s, so it will be interesting to see how doctors perceive this trial data relative to Januvia's data. It's possible they conclude the two are on equal footing or that Tradjenta's evidence is more compelling for patients with kidney disease. If it's the latter, then it could be important because many diabetics also end up with kidney disease.

A second safety trial for Tradjenta is expected to wrap up this year, so data from that trial could influence opinions on Tradjenta relative to Januvia, too. Regardless, this safety data is good news for Eli Lilly because at a minimum, it levels the playing field with Januvia, and that could be enough to allow Tradjenta to chip away at more of Januvia's sales lead.