TL;DR: TRIUMPH-5 (NCT06662383), Lilly’s retatrutide vs tirzepatide Phase 3, lists primary completion Nov 2026; no results yet. Retatrutide is investigational.
Retatrutide vs Tirzepatide: What the TRIUMPH-5 Registry Record Shows (4 November 2026)
What Is TRIUMPH-5 and Why Does It Matter to Researchers?
TRIUMPH-5 is Eli Lilly’s registered Phase 3 trial comparing its investigational triple agonist retatrutide (LY3437943) directly with tirzepatide in adults with obesity. It is listed on ClinicalTrials.gov as NCT06662383 and in the EU Clinical Trials Information System under 2024-511450-49-00.[1][2] Retatrutide engages GIP, GLP-1 and glucagon receptors; tirzepatide engages GIP and GLP-1 receptors. A head-to-head design is therefore the cleanest published test of whether the additional glucagon-receptor activity changes outcomes relative to a dual agonist, and that is why laboratory groups studying multi-receptor pharmacology follow the programme closely.
As of 4 November 2026 we found no results for TRIUMPH-5 from Lilly, a journal or a congress. This article describes the registered design only. Nothing here is a trial result.
The record describes a randomised, double-blind, parallel-assignment study. Registry and tracking-site summaries list an estimated enrolment of roughly 800 (the EU record lists 850), a start in late 2024, and an estimated primary completion of November 2026, reportedly moved earlier from December 2026.[1][3] Registry fields are updated by the sponsor, so check the live record before citing any date.
Sources: ClinicalTrials.gov NCT06662383 · EU CTIS 2024-511450-49-00
What Is the Registered Primary Endpoint?
The registered primary outcome is percent change in body weight from baseline to week 80.[1] Eighty weeks matches the primary timepoint used across the retatrutide obesity programme, which allows indirect comparison of design features with TRIUMPH-1 and the other pivotal studies. Researchers reading the eventual results should check four design details in the full record and publication: the tirzepatide dose arms, whether the analysis uses a treatment-regimen or efficacy estimand, how treatment discontinuation is handled, and whether the comparison is pre-specified as non-inferiority or superiority.
Those details decide how far a headline difference can be generalised. A comparison with a single comparator dose in a single population cannot, on its own, support conclusions about other doses, populations or mechanisms.
How Does TRIUMPH-5 Differ From Earlier Retatrutide Trials?
Most completed retatrutide Phase 3 readouts used placebo or, in TRANSCEND-T2D-2, semaglutide as the comparator. TRIUMPH-5 is the obesity-population trial in the programme with an active incretin comparator of this kind. Our report on the diabetes head-to-head is in TRANSCEND-T2D-2 vs semaglutide; the registered studies are collected in what’s left in the Phase 3 programme and the basket-trial design guide. For earlier comparative context see retatrutide vs tirzepatide vs semaglutide.
Is Retatrutide Approved, and What Is the Filing Timeline?
No. Retatrutide has no marketing authorisation from the FDA, MHRA or any regulator. Lilly’s third-quarter 2026 release on 29 October 2026 reiterated earlier guidance of a US submission in the first quarter of 2027, following completion of the chemistry, manufacturing and controls package.[4] The reasons for that sequencing are discussed in why Lilly delayed the filing to 2027. A primary completion date is not a results date: database lock, analysis and a company announcement typically follow, and Lilly has not said when it would report.
What Should Researchers Watch For Next?
Three things. First, any change to the registry’s status or completion date, which is the earliest public signal. Second, a Lilly topline press release, which will be sponsor-reported and unreviewed. Third, a congress presentation or journal paper supplying the dose-by-dose tables and safety data. Until the full dataset appears, treat any secondary-site claim about TRIUMPH-5 outcomes as unverified.
How Does Licensed Pharma Development Differ From Research-Use Compounds?
TRIUMPH-5 is a regulated clinical programme: a licensed pharmaceutical sponsor, a registered protocol, ethics oversight and medical supervision of participants. Nothing in it transfers to a laboratory reagent. Velox Peptides supplies retatrutide solely as an HPLC-verified in vitro research reagent, with no therapeutic claims, and reports trial news only as third-party information for researchers. For specifications see the research-grade retatrutide page.
This compound is supplied as a research reagent only. It is not a medicine and has not been evaluated by the MHRA or FDA. Not for human or veterinary use. See our Research Use Policy and MHRA Statement.
References
- ClinicalTrials.gov. NCT06662383: A Study of Retatrutide (LY3437943) Compared to Tirzepatide (LY3298176) in Adults Who Have Obesity (TRIUMPH-5). Accessed via search summary, 4 November 2026. clinicaltrials.gov
- EU Clinical Trials Information System. Trial 2024-511450-49-00 (TRIUMPH-5). ctis.eu
- DataLookout. Trial tracker entry for NCT06662383 (completion-date history; secondary source). dashboard.datalookout.com
- Eli Lilly and Company. Third-quarter 2026 financial results (Form 8-K), 29 October 2026. sec.gov
Frequently Asked Questions
What is TRIUMPH-5?
TRIUMPH-5 (NCT06662383) is an Eli Lilly Phase 3 randomised, double-blind trial comparing investigational retatrutide with tirzepatide in adults with obesity. Its registered primary outcome is percent change in body weight from baseline to week 80.
When will TRIUMPH-5 results be available?
The ClinicalTrials.gov record lists an estimated primary completion of November 2026, reportedly moved earlier from December 2026. Lilly has not announced a results date, and a registry date is an estimate, not a commitment.
Is retatrutide approved?
No. Retatrutide is investigational and has no marketing authorisation from the FDA, MHRA or any regulator. Lilly has said it plans a US submission in the first quarter of 2027.
How does TRIUMPH-5 differ from TRANSCEND-T2D-2?
TRANSCEND-T2D-2 compared retatrutide with semaglutide in adults with type 2 diabetes. TRIUMPH-5 compares retatrutide with tirzepatide, a dual GIP/GLP-1 agonist, in adults with obesity, so the comparator and population both differ.
Does this trial apply to research-use retatrutide?
No. The trial concerns a licensed-pharma development programme under clinical supervision. Velox Peptides supplies retatrutide only as an in vitro research reagent, with no therapeutic claims.