Eli Lilly has unveiled promising data from its Phase IIIb SURMOUNT-5 study, showing that its weight loss treatment, Zepbound (tirzepatide), outperforms Novo Nordisk’s Wegovy (semaglutide) in terms of weight reduction.
At the 72-week mark, Zepbound patients lost an average of 22.8 kg (50.3 lbs), compared to 15.0 kg (33.1 lbs) for those on Wegovy. The study demonstrated a 47% greater relative weight loss with Zepbound, with an average weight reduction of 20.2%, compared to 13.7% for Wegovy.
The study also highlighted Zepbound’s superiority in secondary endpoints. Specifically, 31.6% of patients taking Zepbound lost at least 25% of their body weight, while only 16.1% of Wegovy patients achieved this milestone.
Lilly’s senior vice president of global medical affairs, Leonard Glass, expressed excitement over the results, emphasizing that the study will help guide patients and healthcare providers in making informed treatment choices. “Zepbound is in a class of its own as the only FDA-approved dual GIP and GLP-1 receptor agonist obesity medication,” Glass noted.
However, analysts showed a more reserved response. Truist Securities’ Srikripa Devarakonda stated in an investor note that while the data confirms tirzepatide’s competitive edge over semaglutide, the results were in line with prior expectations and would only lead to a marginal increase in Lilly’s share value. Devarakonda also highlighted that upcoming trials, such as the CagriSema study by Novo Nordisk, and the FDA’s decision on tirzepatide’s shortage status, would likely be the next major catalysts for the weight-loss sector.
Similarly, BMO Capital Markets’ Evan David Seigerman noted that the results were largely anticipated, providing formal confirmation of Zepbound’s advantage in efficacy. Seigerman also suggested that the study’s results could allow Lilly to claim a superiority label for tirzepatide in future marketing.
This data aligns with previous findings supporting tirzepatide’s stronger efficacy. A July 2024 study published in JAMA Internal Medicine found that patients on tirzepatide were significantly more likely to achieve weight loss compared to those on semaglutide, with a nearly 7% advantage at the 12-month mark. In addition, a November 2023 analysis by Truveta Research found that patients on Lilly’s diabetes drug, Mounjaro (tirzepatide), experienced more rapid weight loss than those on Novo’s Ozempic (semaglutide). After three months, Mounjaro patients had lost 5.9% of body fat, compared to 3.6% in the Ozempic group. After one year, Mounjaro patients had reduced their body weight by 15.2%, while Ozempic patients had lost 7.9%.
The results of SURMOUNT-5 give Lilly a significant boost in its competition with Novo Nordisk, which has dominated the obesity market, primarily driven by its first-to-market advantage with Ozempic, approved in 2017. Lilly’s Mounjaro was approved by the FDA in 2022. Despite this, Novo’s sales of Ozempic and Wegovy exceeded analyst expectations in the third quarter, while Lilly’s Mounjaro and Zepbound fell short of projections.
SURMOUNT-5 provides further evidence that tirzepatide could help Lilly close the gap with Novo in the growing obesity treatment market, especially with data confirming its superiority in weight loss compared to Wegovy.
