Retatrutide Phase 3: What the TRIUMPH Data Shows
Eli Lilly’s retatrutide has completed multiple Phase 3 trials under the TRIUMPH programme. Here is a summary of what the published data shows, positioned strictly within a research context.
Background: What is TRIUMPH?
TRIUMPH (Treatment of Obesity with Retatrutide — Investigational Uplift in Metabolic Profile and Health) is the Phase 3 clinical development programme for retatrutide, Eli Lilly’s GLP-1/GIP/glucagon triple receptor agonist. The programme comprises multiple trials across obesity, type 2 diabetes, and co-morbid conditions. Results from the first trials were reported in 2026.
TRIUMPH-1: Weight Reduction at 104 Weeks
TRIUMPH-1 is the pivotal obesity trial. In participants receiving retatrutide 12mg once weekly, average body weight reduction reached 30.3% at 104 weeks — equivalent to approximately 85 lbs (38.6 kg) from baseline. All three doses tested (4mg, 9mg, 12mg) met the primary and key secondary endpoints. The 12mg dose consistently produced the largest reductions across all measures.
For research comparison: semaglutide 2.4mg (STEP-1) produced approximately 14.9% weight reduction at 68 weeks; tirzepatide 15mg (SURMOUNT-1) produced approximately 22.5% at 72 weeks.
TRIUMPH-4: Osteoarthritis and Weight
TRIUMPH-4 added an osteoarthritis co-morbidity angle. Participants receiving retatrutide 12mg lost an average of 71.2 lbs alongside statistically significant reductions in osteoarthritis pain scores and improvements in physical function. This was the first Phase 3 trial of any GLP-1 class peptide to incorporate musculoskeletal function as a primary endpoint alongside weight.
TRIUMPH-2 and TRIUMPH-3: Additional Obesity Populations
In July 2026, Eli Lilly reported positive topline results from TRIUMPH-2 and TRIUMPH-3 — two additional pivotal obesity trials with varying patient populations and backgrounds. Both met their primary endpoints. Full data is pending peer-reviewed publication.
TRANSCEND-T2D-1: Type 2 Diabetes
Retatrutide also demonstrated significant HbA1c reduction and weight loss in the TRANSCEND-T2D-1 trial, Lilly’s first Phase 3 study in participants with type 2 diabetes. The 12mg dose produced the largest A1c reductions alongside meaningful body weight change.
FDA Timeline
Eli Lilly has indicated FDA submission is scheduled for Q3 2026, based on the completed TRIUMPH-1 data package. Additional indication submissions (T2D, cardiovascular) are expected to follow as remaining trials complete.
What This Means for Research Context
The TRIUMPH data is significant for the research community studying metabolic and glycaemic pathways. The triple-receptor mechanism — particularly the addition of glucagon receptor activity — is considered the primary driver of the stronger weight outcomes compared to dual-agonist compounds. Researchers comparing GLP-1, GIP, and glucagon pathway contributions will find the incremental data across TRIUMPH doses particularly useful for mechanism-of-action work.
For background on the receptor design, see our comparison: Tirzepatide vs Retatrutide and the overview piece Triple Agonists: The Next Frontier.
Compounds Referenced in This Article
Revial Labs supplies the following compounds discussed in this article, each independently COA tested and dispatched from the UK for laboratory research use only:
This article is provided for educational and informational purposes for laboratory research professionals. All Revial Labs compounds are supplied strictly for laboratory research use only and are not for human or veterinary use.
