Retatrutide Clinical Trials: TRIUMPH Program Guide (2026)

What Is the TRIUMPH Program?

TRIUMPH is Eli Lilly's Phase 3 clinical trial program for retatrutide (LY3437943). Phase 3 trials are the final large-scale stage before a company submits a drug for FDA review. They enroll hundreds or thousands of participants to confirm both efficacy and safety across diverse populations. The TRIUMPH program spans four core trials covering general obesity, obesity plus knee osteoarthritis, obesity with cardiovascular disease, and obesity with type 2 diabetes, with nested protocols studying sleep apnea (OSA) within those same participant groups.

TRIUMPH numbering follows the official ClinicalTrials.gov registration acronyms submitted by Eli Lilly. NCT identifiers and primary completion dates verified against ClinicalTrials.gov as of May 2026.

How Many TRIUMPH Trials Are There?

The four core TRIUMPH studies defined in Giblin et al. 2026 enroll over 5,800 participants combined. Beyond those four, Lilly has filed additional TRIUMPH studies. Trials.lilly.com listed TRIUMPH-7 (chronic low back pain), TRIUMPH-8 (general obesity), and TRIUMPH-9 (obesity without type 2 diabetes) as enrolling as of April 2026, bringing the total program well above eight trials; by October 2026, most retatrutide Phase 3 trials were no longer enrolling. Running eight-plus trials simultaneously signals Lilly is pursuing multiple FDA indications from the start, not sequentially.

TRIUMPH-4 Retatrutide Trials: The First Phase 3 Results (December 2025)

TRIUMPH-4 (NCT05931367) enrolled adults with BMI ≥27 and moderate knee osteoarthritis. It ran for 68 weeks (n=445; primary completion November 2025). Results announced December 2025: participants on 12mg retatrutide lost an average of 28.7% of their body weight, versus 2.1% on placebo. That is 4.5 percentage points higher than Phase 2 (24.2% at 48 weeks, Jastreboff et al. NEJM 2023), with 20 additional weeks of treatment.

The 9mg dose arm showed 26.4% weight loss. The placebo arm showed 2.1%. These results came from a population with obesity and knee osteoarthritis, not a lean or highly motivated trial-completer group.

What Did TRIUMPH-4 Measure?

The primary endpoint was percent change in body weight from baseline to 68 weeks. Secondary endpoints included knee osteoarthritis pain via the WOMAC (Western Ontario and McMaster Universities Arthritis Index) subscale. The 12mg group saw a 76% improvement in WOMAC knee pain scores. That secondary finding matters: it suggests retatrutide may offer joint-pain relief beyond weight loss alone, which could influence future label claims. The trial excluded participants with type 2 diabetes, so the results apply specifically to obesity with OA, not a mixed metabolic population.

TRIUMPH-4 Results at a Glance

Source: Clinical Trials Arena, December 2025, citing Lilly data release. 4mg dose weight-loss value not reported separately in available secondary sources; not extrapolated.

Other Retatrutide Trials Still Ongoing

TRIUMPH-4 is one piece of a much larger program. Seven other TRIUMPH trials are expected to report results in 2026, per Clinical Trials Arena (December 2025). Here is what each covers.

TRIUMPH-1 and TRIUMPH-2: General Obesity and Nested Studies

TRIUMPH-1 and TRIUMPH-2 are the core weight management basket trials. They enroll adults with obesity (BMI 30 or higher, or BMI 27 or higher with a weight-related comorbidity). Both trials include nested protocols studying obstructive sleep apnea (OSA) and knee osteoarthritis within the same participant pool, which means Lilly can generate data on multiple indications without separate enrollment campaigns. The primary endpoint for both is percent change in body weight. Results are expected in 2026. Use the ClinicalTrials.gov retatrutide search to find the current trial status pages.

TRIUMPH-3: Obesity Plus Cardiovascular Disease

TRIUMPH-3 (registered as NCT06383390 on ClinicalTrials.gov) is Eli Lilly's cardiovascular outcomes trial for retatrutide. The enrolled population consists of adults with obesity and established cardiovascular disease. The primary purpose is to determine whether retatrutide significantly lowers the incidence of serious cardiovascular events, including heart attacks, strokes, and cardiovascular death. These events are collectively referred to as major adverse cardiovascular events (MACE).

TRIUMPH-3 follows the same design logic as semaglutide's SELECT trial, which showed cardiovascular benefit and directly expanded Wegovy's FDA label. A positive TRIUMPH-3 result would give retatrutide a similar lever. MACE outcomes take years to accumulate, so this trial runs longer than the weight-loss arms. Results before 2027 are unlikely.

TRIUMPH-7, -8, and -9: The Expanding Program

Lilly has announced additional TRIUMPH studies beyond the original four. TRIUMPH-7 studies retatrutide in adults with obesity and chronic low back pain. TRIUMPH-8 focuses on general obesity. TRIUMPH-9 targets obesity without type 2 diabetes. All three were listed as enrolling at Lilly trial sites as of April 2026 on the Lilly Trials portal. If you are specifically interested in one of these indications, check the Lilly portal or ClinicalTrials.gov for current status, since most retatrutide Phase 3 trials are no longer enrolling.

Clinical Trial Doses Used in Retatrutide Trials

Phase 2 (Jastreboff et al. NEJM 2023, 338 participants) tested four maintenance dose arms: 1mg, 4mg, 8mg, and 12mg, all administered once weekly by subcutaneous injection. The higher-dose arms (4mg, 8mg, 12mg) titrated up from a 2mg starting dose every 4 weeks; the 1mg arm started directly at 1mg without titration. The 12mg dose produced the highest weight loss at 24.2% over 48 weeks.

TRIUMPH-4 Phase 3 narrowed the testing range to three maintenance doses: 4mg, 9mg, and 12mg. The 9mg dose is new relative to Phase 2 and appears to reflect Lilly's refined dose-escalation strategy for the commercial product. All Phase 3 arms use the same standard titration approach: starting at a low dose and escalating every 4 weeks until the target maintenance dose is reached.

For full details on the titration schedule used in trials, see the retatrutide dosing protocol guide.

Are Trial Doses Different from What Would Be Prescribed?

Phase 3 tests the doses Lilly intends to put on the commercial label. The 4mg, 9mg, and 12mg maintenance arms in TRIUMPH-4 are likely the exact options you would see on a prescription. The FDA will confirm which doses get approved and under what conditions. So if you are in a trial on one of those doses, that is probably what commercial retatrutide would look like.

How to Enroll in a Retatrutide Clinical Trial

Trial participation is free. Eli Lilly covers the drug, clinic visits, lab work, and monitoring. Five steps to get started:

Who Qualifies for TRIUMPH Retatrutide Trials?

Per Giblin et al. 2026, the general criteria across TRIUMPH studies are: age 18 or older, BMI 30 or higher (BMI 27 or higher with a comorbidity in some arms), no current GLP-1 receptor agonist use, no recent bariatric surgery, and stable weight for a set period before enrollment. Each arm adds its own requirements on top of those. TRIUMPH-4 required moderate-to-severe knee osteoarthritis. TRIUMPH-3 requires established cardiovascular disease. Check the specific trial listing on ClinicalTrials.gov before assuming you qualify.

What Can Disqualify You from a Retatrutide Clinical Trial?

GLP-1 class trials typically exclude people with: a recent major cardiovascular event (within 90 days in most protocols), personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia type 2 (MEN2), current use of GLP-1 receptor agonists or other weight-loss medications, severe kidney or liver disease, recent bariatric surgery, or active pregnancy. These are patterns across GLP-1 trials generally. TRIUMPH-specific exclusions vary by arm and are listed on each trial's ClinicalTrials.gov page. Use those pages for screening, not this list.

If You Cannot Join a Trial: Lilly's Expanded Access Program

Lilly runs an expanded access program for retatrutide before FDA approval, "for a limited number of patients who meet specific medical criteria and cannot enroll in a clinical trial" (Reuters via KSL). Patients must be 18 or older with a BMI of 35 or more despite tolerating the highest available dose of weight-management therapy, have two or more serious or life-threatening obesity-related complications, be unable to join an ongoing retatrutide (or comparable) trial, and have discussed all standard treatment options, including bariatric surgery, with their doctor (Lilly Medical; ClinicalTrials.gov NCT07629401). The treating physician applies to the FDA as the sponsor of a patient-specific investigational new drug (IND) application and must obtain institutional review board (IRB) approval. Lilly provides the drug at no cost, and direct-to-patient shipping is not available. It is not something a patient can buy.

What the Retatrutide Trials Timeline Means for You

The path from "trials ongoing" to "drug at pharmacy" has five stages. Here is where each stands as of April 2026:

For current FDA status details, see the dedicated retatrutide FDA approval status article. For country-by-country access information once approval occurs, see retatrutide availability by country.

Can the FDA Speed Up Retatrutide Approval?

Two FDA mechanisms could shorten the clock. Breakthrough Therapy Designation gives Lilly more intensive FDA guidance during development but does not compress the review timeline. Priority Review does: it cuts the standard 10-12 month review to about 6 months, and the FDA grants it when a drug offers a meaningful advance over existing treatments.

Retatrutide's TRIUMPH-4 data is stronger than any obesity drug that has gone through FDA review. That gives Lilly a reasonable case to request Priority Review. The FDA had not formally granted it as of April 2026. If it is granted after BLA submission, the approval timeline could move up by several months.

Retatrutide Trials vs Other GLP-1 Drug Trials: Where the Data Stands

Retatrutide has not been tested head-to-head against semaglutide or tirzepatide. But you can see where each compound's landmark trial landed. Different designs and populations mean the numbers are not directly comparable, which is worth keeping in mind when reading coverage that treats them as a ranking.

Caution: Different trial designs and populations make these results non-comparable in a strict scientific sense. No head-to-head retatrutide vs tirzepatide or retatrutide vs semaglutide trial has been conducted. For a detailed comparison, see our retatrutide weight loss results page.

GLP3Planner Calculator: Track Your Retatrutide Protocol

Whether you are in a TRIUMPH trial or following the program from outside, the GLP3Planner calculator is built on retatrutide's actual pharmacokinetics: 6-day half-life, once-weekly injection, 4-5 week steady-state window. You can see exactly when your dose peaks, how concentrations accumulate week over week, and what happens if you adjust your schedule. Free. No account needed.

Frequently Asked Questions: Retatrutide Trials

References: Peer-Reviewed Literature and Trial Registry

1. 1. Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial. New England Journal of Medicine. 2023;389(6):514-526. doi:10.1056/NEJMoa2301972. View on NEJM
2. 2. Giblin K, et al. Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: TRIUMPH clinical development program rationale and design. 2026. PubMed ID: 41090431. View on PubMed
3. 3. ClinicalTrials.gov. A Study of Retatrutide (LY3437943) in Participants With Obesity and Knee Osteoarthritis (TRIUMPH-4). Identifier: NCT05931367. View on ClinicalTrials.gov
4. 4. ClinicalTrials.gov. The Effect of Retatrutide Once Weekly on the Incidence of Serious Cardiovascular Events. Identifier: NCT06383390. View on ClinicalTrials.gov
5. 5. Frias JP, Hsia S, Erichsen L, et al. Efficacy and safety of retatrutide in people with type 2 diabetes: a multicentre, randomised, double-blind, placebo-controlled, phase 1b trial. Lancet. 2023;402(10411):529-544. doi:10.1016/S0140-6736(23)01053-X. View on PubMed
6. 6. Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine. 2021;384:989-1002. doi:10.1056/NEJMoa2032183.
7. 7. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine. 2022;387:205-216. doi:10.1056/NEJMoa2206038.

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