Tirzepatide Achieved Greater Weight Reduction than Placebo in Patients with Obesity

New data suggest tirzepatide achieved superior weight loss than placebo in adults with obesity or overweight at 72 weeks of treatment in the SURMOUNT-1 clinical trial, with individuals losing up to 22.2% of their body weight (52 lb.).

The topline results on the novel once-weekly glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist were reported by Eli Lilly and Company.

“Tirzepatide delivered impressive body weight reductions in SURMOUNT-1, which could represent an important step forward for helping the patient and physician partnership treat this complex disease,” said Louis J. Aronne, MD, director of the Comprehensive Weight Control Center and Sanford I. Weill Professor of Metabolic Research at Weill Cornell Medicine in a statement.

The trial 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. It enrolled a total of 2,539 participants.

Data show 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 ≥5% compared to placebo for both estimands.

For the efficacy estimand, individuals 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% 5lb. or 2 kg).

Furthermore, the findings showed 89% (5 mg) and 96% (10 mg and 15 mg) of people taking tirzepatide achieved ≥5% body weight reduction 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. The mean baseline body weight of individuals was 231 lb.

Regarding the treatment regimen estimand, findings showed the average body weight reductions were 15.0% (5 mg), 19.5% (10 mg), 20.9% (15 mg), and 3.1% (placebo). Further, the percentage of individuals achieving body weight reductions of ≥5% were reported as 85% (5mg), 89% (10 mg), 91% (15mg), and 35% (placebo).

The data additionally show the percentage of patients achieving body weight reductions of ≥20%: 30% (5 mg, not controlled for type 1 error), 50% (10 mg), 57% (15 mg), and 3.1% (placebo).

Moreover, the overall safety and tolerability of the study agent was found similar to other incretin-based therapies approved for obesity treatment.

For individuals treated with tirzepatide (5 mg, 10 mg and 15 mg, respectively), nausea (24.6%, 33.3%, 31.0%), diarrhea (18.7%, 21.2%, 23.0%), vomiting (8.3%, 10.7%, 12.2%) and constipation (16.8%, 17.1%, 11.7%) were more frequently experienced, compared to placebo.

Treatment discontinuation rates due to adverse events were 4.3% (5 mg), 7.1% (10 mg), 6.2% (15 mg), and 2.6% (placebo).

Patients who had prediabetes at study commencement would remain enrolled in SURMOUNT-1 for an additional 104 weeks of treatment to evaluate the impact of the study agent on body weight and progression to type 2 diabetes at 3 years of treatment.

“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," said Jeff Emmick, MD, PhD, vice president, product development, Lilly in an accompanying statement.

Lilly has noted it will continue to evaluate findings from the SURMOUNT-1 trial and additional studies are ongoing for tirzepatide as a potential treatment for patients with obesity or overweight.