Tirzepatide Demonstrates Significant Weight Loss Compared to Placebo

Tirzepatide (Mounjaro; Eli Lilly) demonstrated superior and significant weight loss compared to a placebo in 2 phase 3 studies in adults with obesity or overweight with weight-related comorbidities, according to a news release from Eli Lilly and Company.

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The SURMOUNT-3 and SURMOUNT-4 trials met all primary and key secondary objectives for tirzepatide when compared to placebo. Across both trials, participants on tirzepatide following intensive lifestyle intervention—which included a low-calorie diet, exercise, and counseling sessions—or with continued tirezepatide treatment, achieved up to a 26.6% mean weight loss, according to the release.

"The results of SURMOUNT-3 and -4 showed the highest level of weight loss observed in the SURMOUNT program to date," said Jeff Emmick, MD, PhD, senior vice president of product development at Eli Lilly and Company, in the release. "Whether taking tirzepatide for 88 weeks in SURMOUNT-4 or taking tirzepatide for 72 weeks following intensive caloric restriction in SURMOUNT-3, participants achieved similar mean weight reduction—about 26%.”

SURMOUNT-3 sought to evaluate the efficacy and safety of tirzepatide compared to placebo for 72 weeks after a 12-week intensive lifestyle intervention. The randomized trial assigned participants who had at least 5% body weight reduction by the end of the 12-week intervention to placebo or tirzepatide.

At the beginning of the study, the mean body weight was 241.4 lbs (109.5 kg), and at the end of the 12-week intervention period, participants had achieved 6.9% mean weight loss.

Participants taking tirzepatide lost an average of an additional 21.1% of their body weight, compared to those taking placebo who had a mean weight regain of 3.3% over 72 weeks, for a placebo-adjusted net weight change of -24.5%, according to the press release. Additionally, 94.4% of participants taking tirzepatide had an additional ≥ 5% body weight reduction from randomization compared to 10.7% in the placebo group.

SURMOUNT-4 was initiated to examine the efficacy and safety of tirzepatide compared to placebo for 52 weeks after a 36-week open-label tirzepatide lead-in period. During the 26-week period, all the study participants took tirzepatide; this was followed by a 52-week, double-blind treatment period in which individuals were randomized to either continue tirzepatide or switch to placebo.

For the randomized participants, the mean body weight was 236.6 lbs (107.3 kg) at the beginning of the study. At the end of the 36-week lead-in period, the participants achieved 21.1% mean weight loss.

Those taking tirzepatide lost an average of an additional 6.7% of their body weight since randomization compared with those taking placebo, who experienced a mean weight regain of 14.8% since randomization, for a placebo-adjusted net weight change of -21.4%.

Regarding the secondary endpoint, participants who remained on tirzepatide post-randomization achieved a total of 26.0% mean body weight loss from study entry over the entire 88-week period, according to the press release.

“The findings from SURMOUNT-3 challenge the notion that patients living with obesity or overweight can achieve their weight loss goals with diet and exercise alone,” Emmick continued. “Additionally, the findings from SURMOUNT-4 reinforce that obesity should be regarded like other chronic diseases where chronic therapy may be needed to maintain treatment benefits."

Reference

Tirzepatide demonstrated significant and superior weight loss compared to placebo in two pivotal studies. Lilly. News release. Published July 27, 2023. Accessed July 27, 2023. https://investor.lilly.com/news-releases/news-release-details/tirzepatide-demonstrated-significant-and-superior-weight-loss