Novo Nordisk has accused rival Eli Lilly of running ad campaigns containing “deliberately false” messages that mislead the public about the comparative efficacy of GLP-1 medicines.
In a lawsuit filed Tuesday in New Jersey, the Danish drugmaker said the “false and misleading advertising is causing irreparable harm to Novo Nordisk and to the patients Lilly deceives.” Novo wants the court to order Lilly to stop making the contested claims and to “conduct a corrective advertising campaign” to tell consumers that earlier ads “conveyed a deceptive comparison” of the companies’ medicines.
The case centers on the doses of Novo drugs that Lilly studied in clinical trials and used as comparators in its ads. Novo cited a Lilly TV ad to support its argument. A voiceover and on-screen text stated that, on average, people on Lilly’s Zepbound lost 50 pounds, compared to 33 pounds on Novo’s Wegovy.
The Wegovy data cover patients who received a 2.4-mg dose. Novo won FDA approval for a 7.2-mg dose, which helped patients lose 47 pounds, in March. Lilly’s ad features text at the bottom of the screen stating that the 7.2-mg dose wasn’t tested in the study comparing Zepbound to Wegovy but has since been approved. The ad’s disclaimer failed to appease Novo.
“That footnote is ambiguous, confusing, virtually illegible and wholly inadequate,” Novo said. “Among other flaws, it does nothing to communicate that the new, higher dose of Wegovy is substantially more effective than the doses included in the study, and therefore the ad’s message claiming dramatic superiority of Zepbound is not supportable.”
A Lilly spokesperson defended the company's ads, telling Fierce Pharma via email that the data come from a gold-standard study that is "the only head-to-head, randomized clinical trial directly comparing tirzepatide and semaglutide in weight management." Lilly hit back at Novo.
"Rather than compete on the merits of its products, Novo is asking a court to stop Lilly from communicating the results of that trial," the spokesperson said. "We stand firmly behind our advertising. It is truthful, it is transparent and it is grounded in the most direct scientific evidence available—exactly what patients deserve. We will continue to focus on the science and defend against this lawsuit vigorously.”
Novo also attacked Lilly’s comparisons of Mounjaro and Ozempic, the brand names for the companies’ GLP-1 medicines in diabetes. The lawsuit notes a national TV ad that presented data from a study that compared Mounjaro 15 mg to Ozempic 1 mg. Like in obesity, Novo won approval for a higher dose of Ozempic—2-mg—after the study. Lilly noted the availability of the 2-mg dose in a footnote to its ad.
The lawsuit seeks to turn the “scale and reach” of Lilly’s campaign against the U.S. company. Since April 27, Lilly’s revised Zepbound TV ad has received more than 700 million impressions, Novo said. The breadth of the campaign means the messages reach a large audience, and the competitive harm to Novo “is amplified with each day Lilly’s false and misleading advertising continues to run,” the lawsuit claimed.
Communicating the messages across major broadcast and cable networks and through sponsored social media advertising on TikTok and Facebook is particularly harmful because consumers rely on ads to form their understanding of medicines, Novo said. The drugmaker claimed that: “Lilly’s strategy is to deprive consumers of their right to accurate, up-to-date and complete information.”
The lawsuit starts a new, more combative phase of Novo and Lilly’s battle for the GLP-1 market. While Novo had a first-mover advantage, Lilly is now the market leader. Mounjaro sales hit (PDF) $8.7 billion in the first quarter, compared to (PDF) 27.8 billion Danish krone ($4.2 billion) for Ozempic. Zepbound outsold Wegovy over the same period.
Editor's note: This story has been updated with a statement from Eli Lilly.