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Clinical Trial Outcomes: SURMOUNT vs STEP Programs
The SURMOUNT clinical program (tirzepatide) and STEP program (semaglutide) used near-identical Phase 3 trial designs. Randomized, double-blind, placebo-controlled studies in adults with obesity or overweight plus weight-related comorbidities. Both trials ran 6
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- The SURMOUNT clinical program (tirzepatide) and STEP program (semaglutide) used near-identical Phase 3 trial designs. Randomized, double-blind, placebo-controlled studies in adults with obesity or overweight plus weight-related comorbidities. Both trials ran 68–72 weeks with weekly subcutaneous dosing and structured lifestyle intervention. The endpoints were identical: percentage change in body weight from baseline, percentage of patients achieving ≥5%, ≥10%, ≥15%, and ≥20% weight reduction, and changes in cardiometabolic risk markers including HbA1c, fasting glucose, triglycerides, and blood pressure.
- SURMOUNT-1 results (tirzepatide 5mg, 10mg, 15mg vs placebo): mean weight reduction of 15.0%, 19.5%, and 20.9% respectively at 72 weeks versus 3.1% placebo. The ≥20% weight loss threshold was achieved by 50% of patients on the 15mg dose. A clinical endpoint previously seen only in bariatric surgery cohorts. HbA1c reductions reached 2.07% at the highest dose, with 94% of patients achieving HbA1c <5.7% (prediabetes reversal threshold). Triglycerides dropped by 23%, HDL cholesterol increased by 13%, and systolic blood pressure decreased by 7.4 mmHg. All statistically significant versus placebo.
- STEP-1 results (semaglutide 2.4mg vs placebo): mean weight reduction of 14.9% at 68 weeks versus 2.4% placebo. The ≥20% threshold was reached by 35% of patients. Clinically meaningful but consistently lower than tirzepatide across all weight-loss tiers. HbA1c reduction was 1.6%, with 89% achieving prediabetes reversal. Lipid improvements were present but attenuated compared to tirzepatide: triglycerides decreased by 19%, HDL increased by 9%. The STEP program demonstrated clear efficacy. Our point is that comparing peptides for metabolic syndrome research requires acknowledging that dual-agonist compounds produce measurably larger effects on the same endpoints in the same patient populations.