Novo Nordisk, the maker of Ozempic, is suing Eli Lilly over advertisements comparing some of their biggest-selling drugs.
The ads compare Lilly’s Zepbound with Novo’s Wegovy, and Novo argues they give consumers a misleading picture of how the blockbuster weight-loss drugs stack up.
At the center of the dispute is Lilly’s claim that patients taking Zepbound lost substantially more weight than those taking Wegovy in a direct clinical trial.
Lilly says the comparison is based on a head-to-head clinical trial, which it calls the gold standard for comparing medicines.
Novo says the problem is that the trial did not test a newer, higher dose of Wegovy that is now available to patients.
That disagreement has opened a new legal front in the fierce competition between the two drugmakers in the booming obesity and diabetes market.
Novo Nordisk challenges Lilly’s Zepbound advertising
Novo Nordisk filed a lawsuit on July 21 in U.S. District Court for the District of New Jersey, accusing Lilly of false and misleading advertising involving Zepbound and its diabetes drug Mounjaro.
Novo alleges Lilly’s national advertising campaigns make its medicines appear significantly more effective than competing Novo drugs by relying on clinical trials that did not test doses of Wegovy and Ozempic that are now available.
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One of the Zepbound campaigns cited in the complaint reviewed by TheStreet prominently compares the average weight loss of roughly 50 pounds for patients taking Zepbound with about 33 pounds for patients taking Wegovy.
Those figures come from Lilly’s SURMOUNT-5 trial, which directly compared tirzepatide, the active ingredient in Zepbound, with semaglutide, the active ingredient in Wegovy.
According to the court complaint, participants receiving Zepbound at 10 milligrams or 15 milligrams lost an average of 20.2% of their body weight, compared with 13.7% for participants receiving Wegovy at 1.7 milligrams or 2.4 milligrams.
Novo does not dispute that those were the trial’s results.
Instead, it argues that continuing to use those results in broad comparisons became misleading after a higher 7.2-milligram dose of Wegovy became available.
SURMOUNT-5 did not test that dose.
“As new and more effective treatment options become available, people deserve accurate information that reflects the latest scientific evidence and helps them make informed care decisions,” said John Kuckelman, Senior Vice President and Group General Counsel at Novo Nordisk, in a statement to TheStreet.
“Healthcare companies have a responsibility to keep their public claims accurate and current — ineffective, fine-print disclaimers do not fix the misleading impression created by major national campaigns.”
Eli Lilly stands behind Zepbound comparison
Lilly strongly disputes Novo’s allegations and says its advertising is supported by a randomized clinical trial directly comparing the medicines.
“The gold standard for comparing medicines is a robustly designed, well-conducted head-to-head clinical trial — like SURMOUNT-5, which remains the only head-to-head, randomized clinical trial directly comparing tirzepatide and semaglutide in weight management,” a Lilly spokesperson told TheStreet.
“Rather than compete on the merits of its products, Novo is asking a court to stop Lilly from communicating the results of that trial.”
Lilly said it stands behind its advertising.
“It is truthful, it is transparent, and it is grounded in the most direct scientific evidence available — exactly what patients deserve,” the spokesperson said.
“We will continue to focus on the science and defend against this lawsuit vigorously.”
The competing arguments expose the central issue in the case.
Lilly is relying on a trial that directly tested Zepbound against Wegovy.
Novo argues that the comparison no longer fairly represents the products available today because Wegovy now has a higher approved dose that was never included in that trial.
No head-to-head trial cited in the complaint has directly compared Zepbound with Wegovy at the newer 7.2-milligram dose.
Novo points to newer Wegovy data
Novo argues in its complaint that results from a separate clinical trial of higher-dose Wegovy undermine the impression created by Lilly’s advertising.
According to the lawsuit, Novo’s STEP UP trial found that participants receiving Wegovy 7.2 milligrams achieved an average weight loss of 18.8%, or approximately 47 pounds.
Novo compares that result with a separate Lilly trial, SURMOUNT-1, in which participants receiving Zepbound at 15 milligrams achieved average weight loss of 20.9%, or approximately 48 pounds.
The two medicines were not tested against each other in those trials.
Novo nevertheless argues that the separate results show substantially closer weight loss than the 50-pound-versus-33-pound comparison highlighted in Lilly’s advertising.
The company’s complaint argues that Lilly should conduct a new direct clinical trial comparing the currently available doses before making broad claims about product superiority.
Lawsuit also targets Mounjaro and Ozempic advertising
Novo’s lawsuit extends beyond weight-loss drugs.
The company is also challenging Lilly’s advertising, which compares Mounjaro, its tirzepatide medicine for type 2 diabetes, with Novo’s Ozempic.
Lilly advertising cited in the lawsuit compares a 2.3% reduction in A1C with Mounjaro at 15 milligrams to a 1.9% reduction with Ozempic at 1 milligram.
Novo argues that the comparison is outdated because Ozempic is also available at a higher 2-milligram dose.
The SURPASS-2 trial underlying the comparison tested Mounjaro against Ozempic at 1 milligram and did not include the higher Ozempic dose, according to the complaint.
Novo alleges that disclaimers acknowledging the limitations of the comparisons are not enough to correct the broader impression created by the advertising.
Lilly says its advertising is truthful and transparent.
Novo seeks to stop Lilly ads
Novo is asking the court to stop Lilly from continuing the comparative advertising and is seeking damages and other relief.
The lawsuit alleges the campaigns could influence which drugs patients ask their healthcare providers about and divert demand from Novo’s medicines to Lilly’s competing products.
Novo says Lilly’s Zepbound campaign has reached a particularly large audience.
According to the complaint, a revised Zepbound television commercial that began airing in late April had generated more than 700 million impressions.
The dispute comes as Novo Nordisk and Eli Lilly battle for position in one of the pharmaceutical industry’s fastest-growing markets.
And the lawsuit adds a new question, not simply which drug works better, but what evidence a company needs before it can tell millions of consumers what its drug does.
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