When will TRIUMPH-5 results be available?

Primary completion is November 2026. That is when the last participant completes the primary measurement; topline results typically follow some months later.

Why compare two drugs from the same company?

Because it isolates the scientific question. Both are built on modified GIP scaffolds, so the main difference is retatrutide's glucagon-receptor activity.

Does this mean retatrutide is close to approval?

No. It remains investigational everywhere. Lilly has signalled an FDA filing in Q1 2027, and filing begins a review rather than ending one.

TRIUMPH-5: Retatrutide Head-to-Head vs Tirzepatide

The short answer

TRIUMPH-5 (NCT06662383) is a Phase 3 trial comparing retatrutide directly against tirzepatide in 800 adults with obesity. It began in November 2024 and has a primary completion date of November 2026. It will be the first head-to-head test of a triple agonist against a dual agonist.

Key facts

Registration: NCT06662383
Acronym: TRIUMPH-5
Comparison: Retatrutide vs tirzepatide (LY3298176)
Phase: 3
Enrolment: 800 participants
Started: 1 November 2024
Primary completion: November 2026
Status: Active, not recruiting

Why a head-to-head matters more than another placebo trial

Every comparison currently made between retatrutide and tirzepatide is indirect: TRIUMPH-1's 28.3% against SURMOUNT-1's 20.9%, from separate trials with different populations, durations and estimands. Indirect comparison is the weakest form of evidence for this question. TRIUMPH-5 randomises the same population to both drugs at the same time for the same duration, which removes nearly every confound at once.

What is being tested

Retatrutide is a triple agonist engaging GIP, GLP-1 and glucagon receptors. Tirzepatide is a dual agonist engaging GIP and GLP-1. Both are Eli Lilly compounds built on modified GIP scaffolds, so the trial isolates one variable fairly cleanly: what the glucagon-receptor arm adds. That is an interesting scientific question as well as a commercial one.

Research material referenced

Retatrutide 10mg, third-party HPLC tested

Buy Retatrutide · £49.99

Scale and timing

The trial enrolled 800 participants, began on 1 November 2024, and carries a primary completion date of November 2026. It is listed as active but no longer recruiting. Primary completion is when the last participant completes the primary outcome measurement. It is not the date results are published, and topline release typically follows some months later.

What it will and will not settle

It should settle whether a triple agonist outperforms the best available dual agonist on weight reduction, and how the two compare on tolerability at maximum tolerated doses. It will not address durability after cessation, which is a separate question handled by TRIUMPH-6, and it will not produce cardiovascular outcome data, which requires a different trial design entirely.

The regulatory position is unchanged

Tirzepatide holds marketing authorisations. Retatrutide holds none anywhere, and a head-to-head trial does not alter that. Lilly has signalled an FDA filing in the first quarter of 2027. Nothing in this trial makes retatrutide available outside a registered study, and material supplied for laboratory research is not related to either product.

Frequently asked questions

When will TRIUMPH-5 results be available?: Primary completion is November 2026. That is when the last participant completes the primary measurement; topline results typically follow some months later.
Why compare two drugs from the same company?: Because it isolates the scientific question. Both are built on modified GIP scaffolds, so the main difference is retatrutide's glucagon-receptor activity.
Does this mean retatrutide is close to approval?: No. It remains investigational everywhere. Lilly has signalled an FDA filing in Q1 2027, and filing begins a review rather than ending one.

Extended research context

The Research & Regulatory News deep dive

Deep dive: why 2026 was the year the incretin field split in two

For a decade every meaningful GLP-1 medicine was a peptide, and every one of them was injected. 2026 broke that pattern in both directions at once. In August the MHRA authorised orforglipron, a small molecule with no peptide bonds that works as an ordinary daily tablet. Three months earlier, retatrutide's TRIUMPH-1 reported a 28.3% mean weight reduction. That is the largest figure yet from a single molecule, and achievable only with a peptide capable of engaging three receptors at once. The field is not converging on one answer. It is separating into a convenience track and a magnitude track, and those tracks have different chemistry.

Deep dive: what a marketing authorisation actually means

An authorisation is granted to a specific product, in a specific formulation, for a specific indication, by a specific regulator. It is not a statement about a compound class and it does not transfer. Orforglipron being licensed in the UK tells you nothing about the legal or regulatory status of any other incretin, and nothing at all about compounds that remain investigational. Authorisation is also separate from funding: a licensed medicine is not automatically available on the NHS, which requires a further NICE appraisal.

Deep dive: reading trial results without being misled

Headline percentages are the least transferable part of a trial. A figure is only meaningful alongside its population, its duration, its comparator and its dropout rate. TRIUMPH-1's 28.3% came from an 80-week study in a relatively uncomplicated obesity population; TRIUMPH-3's 22.6% came from adults with severe obesity and established cardiovascular disease, and the gap between those two numbers is mostly population, not potency. Discontinuation rates deserve the same attention as efficacy: 11.3% of the TRIUMPH-1 12 mg arm stopped due to adverse events against 4.9% on placebo, and that figure is routinely dropped from summaries.

Research applications

▸Tracking regulatory status of investigational incretin compounds
▸Understanding the difference between authorisation, NICE appraisal and NHS availability
▸Comparing peptide and non-peptide receptor agonist pharmacology
▸Interpreting Phase 3 topline releases before peer-reviewed publication
▸Verifying trial identity against ClinicalTrials.gov registrations

Handling checklist

✓Check the compound named in a trial registration matches the compound being discussed
✓Confirm the NCT identifier resolves to the acronym being cited
✓Read topline press releases as preliminary until peer-reviewed publication
✓Separate the trial population from the headline percentage before comparing studies
✓Treat authorisation in one jurisdiction as saying nothing about status in another

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Treating a positive Phase 3 as approval

Fix: Filing begins a review that commonly takes a year or more and can end in a request for more data.

✗ Comparing weight-reduction percentages across different trials

Fix: Population, duration and comparator differ; the numbers are not interchangeable.

✗ Assuming one incretin's approval legitimises another compound

Fix: Authorisations are product-specific and do not transfer between compounds.

✗ Citing a TRIUMPH number without checking the NCT identifier

Fix: Verify against ClinicalTrials.gov, as the numbering has been widely misreported.

✗ Reading research material as an alternative to a licensed medicine

Fix: Research material is supplied for laboratory use only and is not a substitute for anything prescribed.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

UKP

Written and reviewed by

The UK Peptides Editorial Team · Research library, UK Peptides

The editorial team is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate. Corrections are made in place and the review date updated.

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TRIUMPH-5: The Retatrutide vs Tirzepatide Head-to-Head