Novo Nordisk sues Eli Lilly over GLP-1 drug ads

Novo Nordisk has sued Eli Lilly, accusing its biggest GLP-1 rival of running ads that mislead patients about weight-loss and diabetes drug comparisons. For investors, the case adds a legal fight to one of pharma’s most closely watched growth markets, where Novo is trying to win back share from Lilly.

GLP-1 medicines are treatments used for obesity and diabetes, and both companies have built major franchises around them. Novo sells Wegovy for obesity and Ozempic for diabetes, while Lilly sells Zepbound for obesity and Mounjaro for diabetes.

Novo filed the lawsuit Tuesday in the U.S. District Court for the District of New Jersey. The company says Lilly’s national advertising compares the strongest doses of Lilly’s drugs against lower doses of Novo’s products, while leaving out newer data on higher-dose versions of Novo’s medicines.

Novo is asking the court to permanently block the disputed ads and require Lilly to run corrective advertising. The company is also seeking monetary damages, though the amount was not disclosed.

Lilly did not immediately respond to a request for comment.

The fight over what patients see in ads

Novo’s complaint targets Lilly campaigns running on television and social media. Novo says those ads rely on older clinical trials that do not include Wegovy’s newer 7.2-milligram dose, which the Food and Drug Administration approved in March.

According to Novo, that higher-dose Wegovy produced average weight loss of about 19%. Novo says a more recent study showed patients on the 7.2-milligram dose lost 47 pounds on average, which it describes in the lawsuit as “clinically consistent” with results for Zepbound in Lilly’s latest rigorous trial.

One Lilly TV ad cited in the lawsuit compares Zepbound with Wegovy and says patients using Lilly’s drug lose 50 pounds on average, compared with 33 pounds for patients taking the 2.4-milligram dose of Wegovy. Novo says that comparison is based on a prior head-to-head trial that tested Zepbound’s highest doses against Wegovy’s 1.7- and 2.4-milligram doses.

Novo argues the ad does not clearly tell viewers that a higher-dose Wegovy is now available. The company says Lilly mentions that product in a small footnote, but calls the disclosure confusing and inadequate because it does not explain the newer dose’s stronger performance versus lower-dose Wegovy.

John Kuckelman, Novo’s group general counsel, said Monday that Lilly’s campaign leaves consumers with the impression that Lilly’s medicines are superior to Novo’s, and that Novo believes the message is inaccurate. He said Novo sent Lilly a cease-and-desist request in April and sued after Lilly declined to remove or correct certain ads.

Novo says no direct trial supports Lilly’s current comparison

The lawsuit says no head-to-head clinical trial has compared the highest currently available doses of Wegovy and Zepbound. On that basis, Novo argues Lilly lacks support for advertising claims that its drugs are more effective.

Novo brought federal and state unfair competition and false advertising claims, including claims under the Lanham Act, a federal law companies can use to challenge allegedly misleading commercial advertising.

The complaint also says the challenged Zepbound TV spot has generated more than 700 million impressions since it began airing around late April, which Novo points to as evidence of the scale of the alleged competitive harm.

Novo also claims Lilly uses a similar approach when advertising Mounjaro against Ozempic, saying Lilly leaves out newer data tied to a higher dose of Novo’s diabetes drug that was approved more than four years ago.

The lawsuit comes as Novo works to counter Lilly’s gains in GLP-1 drugs through a new obesity pill, price cuts and high-dose Wegovy. Lilly’s Zepbound and Mounjaro have gained favor with many providers and patients in recent years because of their strong efficacy, according to Novo’s complaint and comments from Kuckelman.

This story draws on original reporting from CNBC.