If you've followed the GLP-1 category through Phase 3 once, you know what's at stake here. SURMOUNT turned tirzepatide into Mounjaro / Zepbound and reshaped Eli Lilly's revenue base. STEP did the same for semaglutide (Wegovy). Now TRIUMPH is the Phase 3 program for the next molecule in the lineage - retatrutide, the triple GLP-1 / GIP / glucagon agonist whose Phase 2 data reported ~24% weight loss at 48 weeks.
This is a research walk-through of the TRIUMPH program: the five registered trials, what each is measuring, and which readouts will move the needle in 2026 and 2027. RUO framing throughout - retatrutide is investigational, not approved, and supplied by us strictly as a research reagent (GLP-1 RC-R).
| Trial | Population | Primary endpoint | Expected readout |
|---|---|---|---|
| TRIUMPH-1 | Adults with obesity, no diabetes | % body-weight change at 72 weeks | Late 2026 / early 2027 |
| TRIUMPH-2 | Adults with obesity and type 2 diabetes | % body-weight change + HbA1c at 72 weeks | Late 2026 / 2027 |
| TRIUMPH-3 | Obesity with established cardiovascular disease | Major adverse cardiovascular events (MACE) | 2027+ (multi-year) |
| TRIUMPH-4 | Obesity with knee osteoarthritis | WOMAC pain & function score | 2027 |
| TRIUMPH-5 | Metabolic dysfunction-associated steatotic liver disease (MASLD) | Liver fat & biopsy-confirmed steatohepatitis resolution | 2027+ |
All five are registered on ClinicalTrials.gov under sponsor "Eli Lilly and Company" with NCT numbers in the NCT05536323 / NCT05882045 family. Exact timelines are subject to protocol amendments and enrolment progress.
TRIUMPH-1 is the obesity (no T2D) trial - the direct successor to SURMOUNT-1 (tirzepatide) and STEP-1 (semaglutide). It's the trial the entire weight-loss community is watching because its readout will produce the first apples-to-apples (or near-apples) comparison against the existing leaders.
The Phase 2 numbers were achieved at 48 weeks. TRIUMPH-1 runs for 72 weeks. If the trajectory holds, the headline percentage could exceed the Phase 2 figure. If side effects or compliance issues at scale break the trajectory, the Phase 3 number drops. That uncertainty is exactly what the trial exists to resolve.
TRIUMPH-2 enrols obese adults who also have type 2 diabetes. The dual primary endpoints are weight loss and HbA1c reduction. This is the trial that determines whether retatrutide can be positioned as a diabetes drug as well as an obesity drug - the dual-label path that gave Eli Lilly Mounjaro (T2D) and Zepbound (obesity) from the same molecule.
For T2D patients on metformin, current standard of care, the question is whether adding retatrutide is meaningfully better than adding tirzepatide. The Phase 2 sub-analysis suggested it is, but Phase 3 will resolve that with proper statistical power.
The cardiovascular outcomes trial is the long one. It's designed to measure major adverse cardiovascular events (MACE) - cardiovascular death, non-fatal MI, non-fatal stroke - in adults with obesity and established CV disease. Trials of this type take years because they wait for enough events to accrue for statistical significance.
What's at stake: semaglutide already has an FDA-approved CV indication (SELECT trial, 2024). If TRIUMPH-3 reads out positively, retatrutide gets the same regulatory weight - which matters for insurance coverage, prescriber comfort, and the perception of the drug as a "metabolic" therapy rather than just a "weight-loss" therapy.
This is the most-discussed trial in orthopaedic circles. The hypothesis: meaningful weight loss in obese patients with knee osteoarthritis (KOA) produces meaningful improvement in joint pain and function. The primary endpoint is the WOMAC score - the standard validated KOA pain / stiffness / function index used in clinical trials.
If TRIUMPH-4 reads out positively, retatrutide becomes the first GLP-1-class agent with a specific orthopaedic label. That would significantly broaden insurance coverage (KOA is a covered diagnosis everywhere; obesity coverage is patchier in the US) and create a new prescribing channel through orthopaedic and rheumatology clinics rather than just endocrinology and primary care.
Metabolic dysfunction-associated steatotic liver disease (formerly NAFLD / NASH) is one of the largest unmet-need conditions in metabolic medicine. There are very few approved agents. Resmetirom (Rezdiffra) was the first oral MASH-specific approval in 2024; the GLP-1 class is the next obvious entrant.
TRIUMPH-5 measures liver fat (MRI-PDFF), biopsy-confirmed resolution of steatohepatitis, and fibrosis reduction. A positive readout opens the MASLD market and gives Eli Lilly a third major label for retatrutide. The mechanistic case is strong - the glucagon receptor activation directly engages hepatic lipid handling.
Status check. Retatrutide remains investigational in 2026. Phase 3 readouts are pending. Nothing in this article is regulatory clearance, treatment guidance, or a directive to use the compound. New-U supplies retatrutide as a research reagent (GLP-1 RC-R) for laboratory use only, not for human consumption or weight-loss application.
The TRIUMPH readout calendar will reshape the metabolic peptide conversation through 2027. For research buyers and journalists tracking the category, the most consequential dates sit in late 2026 / early 2027 (TRIUMPH-1) and through 2027 (TRIUMPH-2, -4, -5). The cardiovascular outcomes trial (TRIUMPH-3) is the long tail.
For the underlying weight-loss numbers reported in Phase 2 and how they compare to semaglutide and tirzepatide endpoints, see retatrutide weight-loss percentage results. For why the search and sourcing demand is rising ahead of any approval, see retatrutide online sourcing trends.
Sealed vials of research-grade retatrutide, >99% HPLC purity by Janoshik / Freedom Diagnostics. Research use only - not for human consumption. Investigational compound, WADA-prohibited in sanctioned competition.
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