The battle between the world’s two biggest obesity-drug makers has moved from the marketplace to a U.S. courtroom.
Novo Nordisk has sued Eli Lilly, accusing its rival of running misleading advertisements that suggest Lilly’s weight-loss medicines deliver better results than Novo’s products.
The lawsuit, filed in a federal court in New Jersey, targets advertising campaigns for Lilly’s Zepbound weight-loss drug and Mounjaro, which is used to treat type 2 diabetes. Novo claims the advertisements violate federal and state laws governing false advertising and unfair competition.
At the heart of the dispute is how the companies’ medicines were compared.
Novo alleges that Lilly’s advertisements matched the highest approved doses of Zepbound and Mounjaro against lower doses of Novo’s Wegovy and Ozempic, while failing to account for Wegovy’s recently approved 7.2-milligram dose.
The Danish pharmaceutical company argues that the comparisons give consumers a distorted picture of the drugs’ effectiveness by relying on older clinical data.
Lilly, however, has rejected the allegations and said its advertisements are supported by scientific evidence, particularly the results of its SURMOUNT-5 clinical trial. The study compared patients taking 10 mg or 15 mg of Zepbound with patients using 1.7 mg or 2.4 mg of Wegovy.
The U.S. Food and Drug Administration later approved the higher 7.2 mg Wegovy dose.
Lilly said Novo was attempting to prevent the company from publicising the results of a legitimate clinical trial and vowed to fight the lawsuit.
The legal clash comes as the two companies battle for control of the rapidly expanding U.S. obesity-drug market, which analysts expect could surpass $100 billion by the end of the decade.
Novo Nordisk initially led the market with Wegovy, but Lilly’s Zepbound later overtook it. Novo has since sought to regain momentum, including with the launch of an oral version of Wegovy that has attracted strong demand despite Lilly introducing its own competing pill.
Novo is asking the court to order Lilly to pull the disputed advertisements and launch a corrective campaign. The company also plans to seek a preliminary injunction if the ads are not withdrawn voluntarily.
In addition, Novo is seeking financial damages, including profits it says Lilly earned as a result of the advertising campaign.
The Danish drugmaker claims it warned Lilly about the advertisements in April, after the approval of the higher-dose Wegovy. According to Novo, Lilly responded by adding a disclaimer that Novo’s general counsel described as insufficient.
Novo also says the scale of the campaign has been enormous, claiming the advertisements have been shown to consumers more than 700 million times since changes were made following its warning.
The company argues that Lilly’s advertisements present a comparison of roughly 50 pounds of average weight loss for Zepbound against around 33 pounds for Wegovy. Novo says separate studies of the highest approved doses show a much narrower gap, with average weight loss of about 48 pounds for Zepbound and 47 pounds for Wegovy.
The lawsuit adds another front to an already intense commercial rivalry between the two pharmaceutical giants, with both companies fighting not only for prescriptions but also for control over how consumers view the science behind their competing treatments.
