Topline results from the SURMOUNT-5 trial found Eli Lilly’s tirzepatide led to far greater weight loss than Novo Nordisk’s semaglutide, giving Lilly a boost in the race to become America’s go-to GLP-1.
- Semaglutide and tirzepatide both originally received FDA approval for treating adults with T2D, with those approvals later extending to weight loss management.
- Both drugs mimic the GLP-1 hormone, but tirzepatide also mimics another metabolic hormone called GIP.
Over SURMOUNT-5’s 72 week duration, 751 participants across the U.S. and Puerto Rico were randomized to receive the maximum tolerated dose of tirzepatide (10 mg or 15 mg) or semaglutide (1.7 mg or 2.4 mg).
- Tirzepatide led to an average weight loss of 20.2%, well above semaglutide’s 13.7%.
- All patients were either obese or overweight with at least one of the following comorbidities: hypertension, dyslipidemia, obstructive sleep apnea, or CVD.
Tirzepatide also beat out semaglutide in all of the study’s secondary endpoints. Most notably, far more tirzepatide patients achieved 25% body weight reduction than those taking semaglutide (31.6% vs. 16.1%).
These results add to a mounting body of evidence that favors tirzepatide’s GLP-1/GIP targeting mechanism over semaglutide.
- The previous SURMOUNT 3 and 4 trials showed long-term tirzepatide use allows overweight people to shed a massive 26% of their weight, significantly more than semaglutide’s 10.9% to 14.9% reductions.
Despite tizepatide’s apparent advantages, semaglutide still has a sizable sales lead over tirzepatide ($6.8B vs. $4.4B in Q3), due in part to its first-mover status.
The Takeaway
While semaglutide might have been the initial GLP-1 frontrunner, the growing evidence of tirzepatide’s clinical superiority could make it the standard of care for obesity, and potentially the array of other cardiometabolic conditions that GLP-1s have been shown to treat.
