Efficacy and Safety of Tirzepatide Once Weekly in Participants Without Type 2 Diabetes Who Have Obesity or Are Overweight With Weight-Related Comorbidities: A Randomized, Double-Blind, Placebo-Controlled Trial (SURMOUNT-1)

Clinical Trial19 Mar 2026Phase 3High impact● 9/10i

Efficacy and Safety of Tirzepatide Once Weekly in Participants Without Type 2 Diabetes Who Have Obesity or Are Overweight With Weight-Related Comorbidities: A Randomized, Double-Blind, Placebo-Controlled Trial (SURMOUNT-1)

Hudson Biotech

Phase 3 SURMOUNT-1 tests once-weekly tirzepatide at three doses versus placebo in adults without type 2 diabetes who have obesity or are overweight with comorbidities. The randomized, double-blind trial targets 2,539 participants with primary efficacy assessment at 72 weeks. This represents tirzepatide's pivotal obesity trial against placebo, potentially supporting Eli Lilly's bid to compete directly with Wegovy in the non-diabetic obesity market. A prediabetes subgroup continues long-term to assess diabetes prevention.

Strategic Signal

SURMOUNT-1 positions tirzepatide as Eli Lilly's primary challenge to Novo Nordisk's Wegovy dominance in non-diabetic obesity. FDA requires dedicated obesity trials in people without diabetes, making this the regulatory path for broad obesity labeling. Payers will compare weight loss efficacy directly to Wegovy's 15% mean reduction from SELECT. Strong efficacy here could shift the obesity standard of care from GLP-1 monotherapy to dual GIP/GLP-1 agonism.

Weight lossGLP-1Eli Lilly

Original Abstract

This Phase 3 study evaluates the efficacy and safety of once-weekly subcutaneous tirzepatide (a dual GIP and GLP-1 receptor agonist) at 5 mg, 10 mg, or 15 mg versus placebo, each used with a reduced-calorie diet and increased physical activity, in adults without type 2 diabetes who have obesity or are overweight with weight-related comorbidities. The primary efficacy assessment is at Week 72. Participants with prediabetes at randomization may continue in an additional long-term treatment period to assess progression to type 2 diabetes and longer-term weight outcomes. | Condition(s): Obesity; Overweight (Without Type 2 Diabetes) With Weight-related Comorbidities | Primary endpoint(s): Mean percent change in body weight from randomization; Percentage of participants achieving ≥5% body weight reduction from randomization | Enrollment: 2,539 (estimated) | Phase: Phase 3 | Sponsor: Hudson Biotech | Expected completion: 2027-02-14 | Status: Recruiting | Last update: 2026-03-19

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