Efficacy and Safety of Tirzepatide in Japanese Participants With Obesity: A Subpopulation Analysis of the SURMOUNT-1 Trial.

Ishigaki, Yasushi; Yamada, Masamichi; Shingaki, Tomotaka; Oura, Tomonori; Shimomura, Iichiro · Obesity (Silver Spring) · 2026

rct · Level II

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Abstract

This prespecified subpopulation analysis aimed to assess the efficacy and safety of once-weekly tirzepatide versus placebo alongside lifestyle intervention in Japanese adults with obesity or overweight. Data from 102 Japanese adults in the SURMOUNT-1 trial with BMI ≥ 30 kg/m<sup>2</sup> or ≥ 27 kg/m<sup>2</sup> and ≥ 1 weight-related comorbidity were analyzed. Coprimary endpoints were mean percent change in body weight and the proportion of participants who achieved ≥ 5% body weight reduction at week 72. Participants in the tirzepatide 5-, 10-, and 15-mg groups had a statistically significantly greater (all p < 0.001) least squares mean (standard error) percent change in body weight compared with those in the placebo group: -12.0% (1.7%), -22.4% (1.7%), -22.1% (1.6%), and -0.3% (1.6%), respectively. Overall, 91.7%, 100%, and 96.6% of participants in the tirzepatide 5-, 10-, and 15-mg groups, respectively, had ≥ 5% weight reduction at week 72, compared with 15.4% in the placebo group. Significant improvements in cardiometabolic measures were also observed with tirzepatide at week 72 compared to placebo. No new safety concerns were identified. Once-weekly treatment with tirzepatide demonstrated significant reductions in body weight and prespecified cardiometabolic measures compared with placebo in Japanese adults with obesity or overweight. ClinicalTrials.gov identifier: NCT04184622 https://clinicaltrials.gov/study/NCT04184622.

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