What is the TRIUMPH program?

TRIUMPH is Eli Lilly's Phase 3 clinical trial program for retatrutide (LY3437943). It comprises at least five registered trials covering obesity (TRIUMPH-1), obesity with type 2 diabetes (TRIUMPH-2), obesity with cardiovascular disease (TRIUMPH-3), obesity with knee osteoarthritis (TRIUMPH-4), and metabolic dysfunction-associated steatotic liver disease (TRIUMPH-5). Together they're enrolling several thousand participants across multiple countries.

When are TRIUMPH readouts expected?

TRIUMPH-1, the obesity (no diabetes) trial, is the lead study. Its primary completion is projected for late 2026 / early 2027 with topline weight-loss data expected to read out in that window. TRIUMPH-2 follows a similar timeline. The cardiovascular outcomes trial (TRIUMPH-3) is multi-year and reads out later in the decade. Exact dates are subject to enrolment and protocol updates registered on ClinicalTrials.gov.

Will positive TRIUMPH data mean retatrutide gets FDA approved?

Positive Phase 3 outcomes are the regulatory pre-requisite, but approval also requires FDA review of the complete safety/efficacy package, label negotiation, and manufacturing inspection. If TRIUMPH-1 reads out positively in late 2026, the earliest realistic FDA approval window is 2027/28. EMA and MHRA approvals would follow on their own timelines.

Why does the TRIUMPH-4 osteoarthritis trial matter?

TRIUMPH-4 is testing whether retatrutide-driven weight loss translates to improvements in knee osteoarthritis pain and function. If positive, it would establish retatrutide as more than a body-composition drug - and would unlock a separate FDA label for an orthopaedic indication, broadening payer coverage and prescribing footprint.

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Retatrutide Phase 3 Trials: Inside the TRIUMPH Program

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 (Retatrutide).

The Five TRIUMPH Trials at a Glance

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: The Lead Trial

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.

Population: adults with BMI ≥30 (or ≥27 with weight-related comorbidities)

Duration: 72 weeks (matching SURMOUNT-1 design)

Primary endpoint: percent change in body weight from baseline

Key secondary endpoints: % achieving ≥5%, ≥10%, ≥15%, ≥20%, ≥25% weight loss; waist circumference; cardiometabolic risk markers

Doses tested: escalating retatrutide arms (typically 1mg, 4mg, 8mg, 12mg weekly) vs placebo

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: Adding the T2D Layer

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.

TRIUMPH-3: The CV Outcomes Trial

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.

TRIUMPH-4: The Knee Osteoarthritis Trial

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.

TRIUMPH-5: MASLD

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.

What to Watch in 2026 / 2027

TRIUMPH-1 topline (late 2026 / Q1 2027). The headline percentage. Anything above 22% solidifies retatrutide as best-in-class on weight. Anything above 25% reshapes the market.

Discontinuation rate. Phase 2 showed dose-dependent GI side effects. Phase 3 will reveal what proportion of participants stay on the higher doses long enough to achieve the headline weight loss in real-world use.

Dose-response at 12mg vs higher. Whether Eli Lilly tests doses above 12mg in TRIUMPH and what the curve looks like.

TRIUMPH-4 WOMAC outcomes. If this is positive, it changes the commercial geography of the drug significantly.

FDA filing timeline. The fastest realistic path is FDA submission in H1 2027 with action by H1 2028. EMA / MHRA on their own clocks.

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 (Retatrutide) for laboratory use only, not for human consumption or weight-loss application.

What This Means for the Research Conversation

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.

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Retatrutide Phase 3 Trials: Inside the TRIUMPH Program

The Five TRIUMPH Trials at a Glance

TRIUMPH-1: The Lead Trial

TRIUMPH-2: Adding the T2D Layer

TRIUMPH-3: The CV Outcomes Trial

TRIUMPH-4: The Knee Osteoarthritis Trial

TRIUMPH-5: MASLD

What to Watch in 2026 / 2027

What This Means for the Research Conversation

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