Two phase 3 tirzepatide studies announced in adults with obesity or overweight with weight-related comorbidities, excluding type 2 diabetes. SURMOUNT-3 and SURMOUNT-4 met all primary and key secondary objectives.
SURMOUNT-3 (NCT04657016) was a multi-center, randomized, double-blind, parallel, placebo-controlled trial comparing the efficacy and safety of tirzepatide to placebo for 72 weeks after a 12-week intensive lifestyle intervention lead-in period in adults with obesity or overweight with weight-related comorbidities, excluding type 2 diabetes. The trial enrolled 806 participants across the U.S., Argentina, Brazil and Puerto Rico to a lead-in period with intensive lifestyle intervention. After 12 weeks, 579 participants achieved at least 5% body weight reduction and were randomized in a 1:1 ratio to receive tirzepatide or placebo. The co-primary objectives of the study were to demonstrate that tirzepatide is superior in percentage change in body weight from randomization and percentage of participants achieving ≥5% body weight reduction from randomization at 72 weeks compared to placebo.
SURMOUNT-4 (NCT04660643) was a multi-center, randomized, double-blind, parallel, placebo-controlled trial comparing the efficacy and safety of tirzepatide to placebo in adults with obesity or overweight with weight-related comorbidities, excluding type 2 diabetes. The trial had two periods: a 36-week open-label lead-in period in which all participants took tirzepatide, and a subsequent 52-week double-blind treatment period in which participants were randomized to either continue on tirzepatide or switch to placebo. The trial enrolled 783 participants across the U.S., Argentina, Brazil, Puerto Rico and Taiwan into the open-label lead-in period and 670 participants were randomized in a 1:1 ratio in the 52-week double-blind treatment period to receive tirzepatide or placebo. The primary objective of the study was to demonstrate that tirzepatide is superior in percentage change in body weight from randomization at 88 weeks compared to placebo.
While SURMOUNT-1 and SURMOUNT-2 had fixed weekly tirzepatide doses, participants in SURMOUNT-3 and SURMOUNT-4 utilized a maximum tolerated dose of 10 mg or 15 mg once-weekly. The starting dose of 2.5 mg tirzepatide was increased by 2.5 mg every four weeks until maximum tolerated dose was achieved. Participants who tolerated 15 mg continued on 15 mg as their maximum tolerated dose. Participants who tolerated 10 mg but did not tolerate 15 mg continued on 10 mg as their maximum tolerated dose.
The SURMOUNT phase 3 global clinical development program for tirzepatide in chronic weight management began in late 2019 and has enrolled more than 5,000 people with obesity or overweight across six registration studies, four of which are global studies. The primary period of SURMOUNT-1 was completed in 2022 and SURMOUNT-2 was completed in the first half of 2023.
About tirzepatide
Tirzepatide is a once-weekly GIP (glucose-dependent insulinotropic polypeptide) receptor and GLP-1 (glucagon-like peptide-1) receptor agonist. Tirzepatide is a single molecule that activates the body’s receptors for GIP and GLP-1, which are natural incretin hormones. Both GIP and GLP-1 receptors are found in areas of the human brain important for appetite regulation. Tirzepatide was approved as Mounjaro® (tirzepatide) by the FDA on May 13, 2022.
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