Tirzepatide  achieved superior weight loss compared to placebo at 72 weeks of treatment in topline results from Eli Lilly and Company’s SURMOUNT-1 clinical trial, with participants losing up to 22.5% (52 lb. or 24 kg) of their body weight for the efficacy estimandi.

Obesity is a complex disease involving an excessive amount of body fat. Obesity isn’t just a cosmetic concern. It’s a medical problem that increases the risk of other diseases and health problems, such as heart disease, diabetes, high blood pressure and certain cancers.

This study enrolled 2,539 participants and was the first phase 3 global registration trial evaluating the efficacy and safety of tirzepatide in adults with obesity, or overweight with at least one comorbidity, who do not have diabetes. Tirzepatide met both co-primary endpoints of superior mean percent change in body weight from baseline and greater percentage of participants achieving body weight reductions of at least 5% compared to placebo for both estimandsii. The study also achieved all key secondary endpoints at 72 weeks.

For the efficacy estimand, participants taking tirzepatide achieved average weight reductions of 16.0% (35 lb. or 16 kg on 5 mg), 21.4% (49 lb. or 22 kg on 10 mg) and 22.5% (52 lb. or 24 kg on 15 mg), compared to placebo (2.4%, 5 lb. or 2 kg). Additionally, 89% (5 mg) and 96% (10 mg and 15 mg) of people taking tirzepatide achieved at least 5% body weight reductions compared to 28% of those taking placebo.

In a key secondary endpoint, 55% (10 mg) and 63% (15 mg) of people taking tirzepatide achieved at least 20% body weight reductions compared to 1.3% of those taking placebo. In an additional secondary endpoint not controlled for type 1 error, 32% of participants taking tirzepatide 5 mg achieved at least 20% body weight reductions. The mean baseline body weight of participants was 231 lb. (105 kg).

Jeff Emmick, MD, Ph.D., vice president, product development, Lilly, said:

Tirzepatide is the first investigational medicine to deliver more than 20 percent weight loss on average in a phase 3 study, reinforcing our confidence in its potential to help people living with obesity.

Tirzepatide is a novel investigational once-weekly GIP (glucose-dependent insulinotropic polypeptide) receptor and GLP-1 (glucagon-like peptide-1) receptor agonist, representing a new class of medicines being studied for the treatment of obesity. Tirzepatide is a single peptide that activates the body’s receptors for GIP and GLP-1, two natural incretin hormones.

Lilly will continue to evaluate the SURMOUNT-1 results, which will be presented at an upcoming medical meeting and submitted to a peer-reviewed journal. Additional studies are ongoing for tirzepatide as a potential treatment for obesity or overweight.