Retatrutide After TRIUMPH: Every Phase 3 Result So Far and the 2027 FDA Filing
Retatrutide Phase 3: TRIUMPH-1 to -4 and TRANSCEND-T2D-1 in one table, the dysesthesia signal, and Lilly's Q1 2027 BLA plan.
For laboratory research use only. Not for human consumption.
TL;DR: Retatrutide, Eli Lilly's once-weekly GIP, GLP-1 and glucagon receptor agonist, has now reported its main Phase 3 obesity trials. In TRIUMPH-1 (adults without diabetes) the highest dose produced 28.3% average weight loss at 80 weeks versus 2.2% on placebo; in TRIUMPH-2 (with type 2 diabetes) 20.8% versus 4.0%; in TRIUMPH-3 (with cardiovascular disease) up to 22.6%. Lilly plans to submit a Biologics License Application to the FDA in Q1 2027. Retatrutide is not approved anywhere, and the trial data apply to Lilly's product, not to research-grade material.
Last verified: 3 November 2026, against Lilly press releases. Percentages are Lilly's efficacy-estimand figures unless stated otherwise. Dose levels are not reproduced here.
Where Retatrutide Stands in November 2026
Retatrutide (LY3437943) is a single peptide that activates three receptors: GIP, GLP-1 and glucagon. The glucagon component is what distinguishes it from tirzepatide (GIP/GLP-1) and semaglutide (GLP-1 only); it is thought to add energy expenditure and liver-fat effects to the appetite effects of the incretin pathways. Lilly describes retatrutide as investigational and first-in-class.
With TRIUMPH-2 and TRIUMPH-3 reported in July 2026, Lilly said it had the data package for global submissions in obesity, knee osteoarthritis pain and obstructive sleep apnoea, and that it plans to submit a BLA to the FDA in Q1 2027. No approval decision has been made in any market.
Phase 3 Results at a Glance
| Trial | Population | Duration | Highest-dose result | Placebo | Reported |
|---|---|---|---|---|---|
| TRIUMPH-4 | Obesity with knee osteoarthritis | 68 weeks | Up to −28.7% body weight; WOMAC pain up to −4.5 points | – | 11 Dec 2025 |
| TRANSCEND-T2D-1 | Type 2 diabetes (537 randomised) | 40 weeks | A1C up to −2.0 points from 7.9%; weight up to −16.8% | – | 19 Mar / 6 Jun 2026 |
| TRIUMPH-1 | Obesity or overweight without diabetes (2,339 randomised) | 80 weeks | −28.3%; 45.3% lost at least 30% | −2.2% | 21 May / 6 Jun 2026 |
| TRIUMPH-2 | Obesity or overweight with type 2 diabetes | 80 weeks | −20.8%; A1C −1.5 points from 7.7% | −4.0%; A1C −0.2 | 23 Jul / 29 Sep 2026 |
| TRIUMPH-3 | Severe obesity with established cardiovascular disease | 80 weeks | Up to −22.6% | – | 23 Jul 2026 |
TRIUMPH-1 also contained two nested basket trials. Lilly reported reductions in knee osteoarthritis pain of up to 4.3 points (73.1%) and in sleep-apnoea severity of up to 36.1 events per hour (60.6%). In a pre-specified extension to 104 weeks for participants with a baseline BMI of 35 or more, average weight loss on the highest dose reached 30.3%.
Reading the Numbers: Two Estimands
Lilly's headline figures use the efficacy estimand, which estimates the effect had participants stayed on treatment as intended. The treatment-regimen estimand counts everyone randomised, including those who stopped, and is usually lower. Journal publications and regulators often lead with the treatment-regimen figure, which is why published percentages for the same trial can differ by a few points from the press releases. Both are correct; they answer different questions.
Safety Signals Worth Watching
Adverse events were broadly in line with other incretin drugs, led by gastrointestinal effects. In TRIUMPH-1 on the highest dose, nausea occurred in 42.4% of participants versus 14.8% on placebo, diarrhoea in 32.0% versus 13.5%, and vomiting in 25.3% versus 4.8%.
One signal is less familiar: dysesthesia – abnormal skin sensations such as tingling or burning – was reported in 12.5% of participants on the highest dose versus 0.9% on placebo in TRIUMPH-1. Lilly describes the events as generally mild to moderate and mostly resolving during treatment. It is not a typical finding for the GLP-1 class and is likely to receive attention during regulatory review.
In TRIUMPH-2, discontinuation due to adverse events ranged from 3.8% to 11.6% across retatrutide doses versus 4.9% on placebo. In TRIUMPH-3, major cardiovascular events occurred less often than anticipated in both arms; the pre-specified MACE-5 analysis gave a hazard ratio of 0.82 (95% CI 0.55–1.22), which does not establish a cardiovascular benefit.
What Comes Next
- BLA submission to the FDA planned for Q1 2027, per Lilly.
- Further Phase 3 programmes listed by Lilly include chronic low back pain, cardiovascular and renal outcomes, and metabolic dysfunction-associated steatotic liver disease.
- Additional TRANSCEND-T2D readouts in type 2 diabetes.
- Lilly has not published an expected FDA decision date.
What the Trials Do Not Say About Research-Grade Retatrutide
Every number above was produced with Lilly's GMP-manufactured product under controlled trial conditions. Retatrutide sold online as a research chemical comes from a different supply chain, and its identity, purity and contamination have to be established batch by batch. Retatrutide is the most frequently tested compound in ChemVerify's archive: Janoshik Analytical reports on samples from five vendors are published at chemverify.com/tests, including a sample that failed. US regulators have also targeted online sellers of research-labelled GLP-1 compounds, including retatrutide, with warning letters in 2026.
Frequently Asked Questions
Is retatrutide FDA approved?
No. Retatrutide is investigational. Lilly plans to submit a Biologics License Application to the FDA in Q1 2027.
When could retatrutide be approved?
Lilly has not given a decision date. An FDA decision would follow review of the application planned for Q1 2027; any specific approval date before then is speculation.
How much weight loss did retatrutide produce in Phase 3?
In TRIUMPH-1, participants on the highest dose lost an average of 28.3% of body weight at 80 weeks versus 2.2% on placebo (efficacy estimand). In people with type 2 diabetes (TRIUMPH-2) the figure was 20.8% versus 4.0%.
What is dysesthesia in the retatrutide trials?
Dysesthesia means abnormal skin sensations such as tingling or burning. In TRIUMPH-1 it was reported in 12.5% of participants on the highest dose versus 0.9% on placebo, mostly mild to moderate.
Is research-grade retatrutide the same as Lilly's?
Not necessarily. The clinical results apply to Lilly's manufactured product. Material sold for research use has its own supply chain, and its quality has to be verified with independent testing.
Check vendors, lab reports and prices on ChemVerify – every independently commissioned test, including failed samples, is published at chemverify.com/tests.
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