18+ · Research Use Only · Not for Human Consumption
Retatrutide · Phase 3 · Completed
TRIUMPH-1
In TRIUMPH-1, a phase 3 trial of retatrutide in adults with obesity, or overweight with at least one weight-related condition, without diabetes (n=2,339), mean body weight fell 19.0% on 4 mg, 25.9% on 9 mg and 28.3% on 12 mg over 80 weeks, against 2.2% on placebo (efficacy estimand; Eli Lilly topline release, 21 May 2026).
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Results
Side effects reported
In TRIUMPH-1, discontinuation because of adverse events was 4.1% on 4 mg, 6.9% on 9 mg and 11.3% on 12 mg, against 4.9% on placebo. The most frequently reported adverse events were nausea in 28.6% on 4 mg, 38.4% on 9 mg and 42.4% on 12 mg against 14.8% on placebo, diarrhoea in 25.2% on 4 mg, 34.1% on 9 mg and 32.0% on 12 mg against 13.5% on placebo, constipation in 23.8% on 4 mg, 25.9% on 9 mg and 26.1% on 12 mg against 10.9% on placebo and vomiting in 10.6% on 4 mg, 22.8% on 9 mg and 25.3% on 12 mg against 4.8% on placebo.
| Event | 4 mg | 9 mg | 12 mg | Placebo |
|---|---|---|---|---|
| Discontinuation for adverse events | 4.1% | 6.9% | 11.3% | 4.9% |
| Nausea | 28.6% | 38.4% | 42.4% | 14.8% |
| Diarrhoea | 25.2% | 34.1% | 32.0% | 13.5% |
| Constipation | 23.8% | 25.9% | 26.1% | 10.9% |
| Vomiting | 10.6% | 22.8% | 25.3% | 4.8% |
| Dysesthesia | 5.1% | 12.3% | 12.5% | 0.9% |
| Urinary tract infection | 7.5% | 8.8% | 8.4% | 5.3% |
Design
Trial design and sources
- Compound
- Retatrutide
- Phase
- 3
- Population
- Adults with obesity, or overweight with at least one weight-related condition, without diabetes
- Participants randomised
- 2,339
- Duration
- 80 weeks
- Primary endpoint
- Percent change in body weight from baseline at 80 weeks
- Estimand
- efficacy
- Read out
- 21 May 2026
A pre-specified extension of 532 participants with a baseline BMI of 35 or more reached -30.3% on 12 mg at 104 weeks (efficacy estimand). The treatment-regimen estimand at 80 weeks was -17.6%, -23.7% and -25.0% against -3.9% on placebo.
Questions
TRIUMPH-1, answered
What did TRIUMPH-1 find?
In TRIUMPH-1, a phase 3 trial of retatrutide in adults with obesity, or overweight with at least one weight-related condition, without diabetes (n=2,339), mean body weight fell 19.0% on 4 mg, 25.9% on 9 mg and 28.3% on 12 mg over 80 weeks, against 2.2% on placebo (efficacy estimand; Eli Lilly topline release, 21 May 2026).
What side effects were reported in TRIUMPH-1?
In TRIUMPH-1, discontinuation because of adverse events was 4.1% on 4 mg, 6.9% on 9 mg and 11.3% on 12 mg, against 4.9% on placebo. The most frequently reported adverse events were nausea in 28.6% on 4 mg, 38.4% on 9 mg and 42.4% on 12 mg against 14.8% on placebo, diarrhoea in 25.2% on 4 mg, 34.1% on 9 mg and 32.0% on 12 mg against 13.5% on placebo, constipation in 23.8% on 4 mg, 25.9% on 9 mg and 26.1% on 12 mg against 10.9% on placebo and vomiting in 10.6% on 4 mg, 22.8% on 9 mg and 25.3% on 12 mg against 4.8% on placebo.