Eli Lilly announces SURMOUNT-3, SURMOUNT-4 trials met all primary endpoints

Eli Lilly announced results of two phase 3 tirzepatide studies 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 for tirzepatide compared to placebo. Across SURMOUNT-3 and SURMOUNT-4, participants on tirzepatide following intensive lifestyle intervention or with continued tirzepatide treatment, achieved up to 26.6% mean weight loss, for the efficacy estimandi. The overall safety profile of tirzepatide in both studies was similar to previously reported SURMOUNT and SURPASS trials and to that of incretin-based therapies approved for the treatment of obesity and overweight. The most commonly reported adverse events in both trials were gastrointestinal-related and generally mild to moderate in severity. SURMOUNT-3 evaluated the efficacy and safety of tirzepatide compared to placebo for 72 weeks after a 12-week intensive lifestyle intervention lead-in period that included a low-calorie diet, exercise and weekly counseling sessions. The trial randomized adults with obesity or overweight who had at least 5% body weight reduction by the end of the 12-week lead-in period to placebo or tirzepatide. At study entry, the mean body weight was 241.4 lb. At the end of the 12-week lead-in period, participants achieved 6.9% mean weight loss. Tirzepatide met both co-primary endpoints demonstrating superiority to placebo during the 72-week double-blind treatment period. For the efficacy estimand, those taking tirzepatide, on average, lost an additional 21.1% of their body weight from randomization, a co-primary endpoint, compared to those taking placebo who experienced mean weight regain of 3.3% over 72 weeks, for a placebo-adjusted net weight change of -24.5%. In addition, 94.4% of those taking tirzepatide achieved an additional =5% body weight reduction from randomization, the other co-primary endpoint, compared to 10.7% in the placebo group over 72 weeks. In a secondary endpoint, participants receiving tirzepatide had a total mean weight reduction of 26.6% from study entry after 12 weeks of intensive lifestyle intervention followed by 72 weeks of tirzepatide treatment. For the treatment-regimen estimandii, those taking tirzepatide, on average, lost an additional 18.4% of their body weight from randomization compared to those taking placebo who experienced mean weight regain of 2.5% over 72 weeks. In addition, 87.5% of those taking tirzepatide achieved an additional 5% body weight reduction from randomization compared with 16.5% in the placebo group over 72 weeks. Participants receiving tirzepatide had a total mean weight reduction of 24.3% from study entry after 12 weeks of intensive lifestyle intervention followed by 72 weeks of tirzepatide treatment. The full results of the SURMOUNT-3 study will be presented at the ObesityWeek conference in October and submitted for publication in a peer-reviewed journal. SURMOUNT-4 evaluated the efficacy and safety of tirzepatide compared to placebo for 52 weeks after a 36-week open-label tirzepatide lead-in period. The trial had two periods: a 36-week open-label lead-in period during which all participants took tirzepatide, followed by a 52-week double-blind treatment period during which participants were randomized to either continue on tirzepatide or switch to placebo. For randomized participants, the mean body weight was 236.6 lb. at study entry. At the end of the 36-week tirzepatide lead-in period, they achieved 21.1% mean weight loss. Tirzepatide met the primary endpoint of superior mean percent change in body weight compared to placebo from 36 weeks to 88 weeks, indicating sustained weight loss. For the efficacy estimand, those taking tirzepatide, on average, lost an additional 6.7% of their body weight from randomization, compared to those taking placebo who experienced mean weight regain of 14.8% from randomization at 88 weeks, for a placebo-adjusted net weight change of -21.4%. In a secondary endpoint, participants who remained on tirzepatide after randomization achieved a total of 26.0% mean body weight loss from study entry over the entire 88-week period. For the treatment-regimen estimand, those taking tirzepatide, on average, lost an additional 5.5% of their body weight from randomization, compared to those taking placebo who experienced mean weight regain of 14.0% from randomization at 88 weeks. Participants who remained on tirzepatide after randomization achieved a total of 25.3% mean body weight loss from study entry over the entire 88-week period. The full results of the SURMOUNT-4 study will be presented at the European Association for the Study of Diabetes Annual Meeting in October and submitted for publication in a peer-reviewed journal.