Zepbound tops Wegovy in first head-to-head weight-loss trial

Eli Lilly is playing catch-up to Novo Nordisk in the fast-growing obesity therapy sector, but has new data that could tip the balance in its favour.

The results of the first head-to-head trial of Lilly's dual GLP-1/GIP agonist Zepbound (tirzepatide) and Novo Nordisk's GLP-1 agonist Wegovy (semaglutide) have shown experimentally what has been speculated via indirect comparisons for some time – Zepbound is better at helping patients shed weight.

In fact, it is 47% better, according to just-released top-line data from the SURMOUNT-5 trial, which showed that patients treated with the maximum tolerated dose of tirzepatide achieved a 20.2% reduction in weight at 72 weeks, compared to 13.7% with the maximum tolerated dose of semaglutide.

In a key secondary endpoint, 31.6% of people taking tirzepatide achieved at least 25% body weight loss compared to 16.1% of those receiving semaglutide, according to Lilly, which said it plans to present the data in full at a medical meeting next year.

The trial involved 751 patients with obesity or who were overweight with at least one comorbidity, such as high blood pressure, elevated cholesterol, obstructive sleep apnoea, or cardiovascular disease, but who did not have diabetes. Safety data was in line with expectations, with both drugs causing mild to moderate gastrointestinal symptoms.

"These new head-to-head clinical trial results underscore that tirzepatide, with a 6.5 percentage point greater weight reduction, provides a clinically meaningful difference in weight loss compared to semaglutide," said Dr Kunal Gulati, head of cardiometabolic medical affairs at Lilly Northern Europe.

"Tirzepatide is the only approved dual GIP and GLP-1 receptor agonist for weight management and this evidence will be important for healthcare professionals in making informed decisions in the treatment of obesity," he added.

The results could help Lilly gain ground on Novo Nordisk in the obesity market, which is currently dominated by first-to-market Wegovy and Zepbound. In the third quarter, Novo Nordisk reported Wegovy sales grew 79% to almost $2.5 billion, while Lilly booked $1.26 billion from Zepbound, around $500 million lower than analyst forecasts.

Both drugs have been held back by shortages in supply, which have started to be resolved thanks to multibillion-dollar investments in manufacturing capacity at both companies.

GlobalData recently predicted that Zepbound sales will top $25 billion by 2030, ahead of Wegovy with $19.4 billion, while the versions of the drug to treat diabetes – Mounjaro and Ozempic – will bring in $32.4 billion and 23.4 billion, respectively.

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