What's Left in Retatrutide's Phase 3 Programme: TRIUMPH-2, TRIUMPH-3 and the Cardiovascular Data Gap

What Has Retatrutide's Phase 3 Programme Reported So Far?

By July 2026, Eli Lilly's retatrutide (LY3437943) Phase 3 programme has produced two headline TRIUMPH readouts plus one from a separately branded diabetes trial. TRIUMPH-1, in adults with obesity or overweight but without diabetes, reported topline results on 21 May 2026: 28.3% mean weight loss at 80 weeks on the 12 mg dose, rising to 30.3% at 104 weeks in a baseline-BMI-≥35 subgroup, with roughly 45% of 12 mg participants losing 30% or more of body weight.[1] TRIUMPH-4, in adults with obesity/overweight and knee osteoarthritis, reported topline results in December 2025: up to 28.7% weight loss at 68 weeks alongside measurable reductions in knee pain scores.[2] Separately, TRANSCEND-T2D-1 — a Phase 3 trial in people with type 2 diabetes, branded outside the TRIUMPH programme — was published in The Lancet on 6 June 2026, reporting HbA1c reductions approaching 2.0 percentage points and weight loss of up to roughly 17% at 40 weeks.[3]

That leaves two further TRIUMPH-branded studies — TRIUMPH-2 and TRIUMPH-3 — plus a much larger, longer-horizon cardiovascular and kidney outcomes trial still to report. None of the three has published results as of this article's publication date.

What Is TRIUMPH-2 Testing, and When Will It Report?

TRIUMPH-2 matters because it is the first Phase 3 comparison point for how retatrutide performs specifically in a population that has both conditions together, rather than obesity alone (TRIUMPH-1) or diabetes with a broader BMI range (TRANSCEND-T2D-1, which also excluded participants already on other glucose-lowering medication and used a shorter 40-week design). Weight-loss and glycaemic results in a dedicated dual-diagnosis population will be a distinct data point rather than a simple average of the two trials already reported.

What Is TRIUMPH-3 Testing?

Why Doesn't TRIUMPH-3 Answer the Cardiovascular Safety Question?

This is the detail that tends to get lost in headline coverage of retatrutide's trial roster: TRIUMPH-3 measures weight loss in people who happen to have heart disease. It is not designed, sized, or statistically powered to detect a difference in cardiovascular event rates between retatrutide and placebo — that is a fundamentally different kind of trial. The distinction matters given our separate coverage of TRANSCEND-T2D-1's cardiac-event imbalance (7 of 403 retatrutide participants experienced arrhythmia versus 0 of 134 on placebo): that trial, like TRIUMPH-3, was not built to test cardiovascular safety as its primary question either, and neither will resolve it on its own.

The trial that is built for that purpose sits outside the TRIUMPH-1-through-4 numbering entirely: a dedicated, event-driven cardiovascular and kidney outcomes trial enrolling roughly 10,000 participants with atherosclerotic cardiovascular disease and/or chronic kidney disease.[6] Unlike the weight-management trials, this study's primary endpoint is the incidence of major adverse cardiovascular events (MACE) and major adverse kidney events, and its completion is not fixed to a calendar date — it depends on how quickly a pre-specified number of events accrue across the roughly five-year study.

When Will Retatrutide's Definitive Cardiovascular Outcomes Data Arrive?

Because the outcomes trial is event-driven rather than time-driven, published timeline estimates vary and Lilly has not confirmed a fixed readout date. Trade-press trials trackers following its enrolment — reported complete around Q4 2025 — project a primary readout no earlier than 2027, with some industry estimates extending into 2028–2029 depending on how quickly cardiovascular and kidney events accrue in the roughly 10,000-participant cohort. Readers should treat these as trade-press projections rather than a company-confirmed date.

This is the same pattern the wider GLP-1 class has followed before: semaglutide's SELECT and tirzepatide's SURPASS-CVOT cardiovascular outcomes trials both reported years after their respective drugs' initial approvals for weight management, not before. There is no regulatory requirement for an outcomes trial to complete before an initial obesity or diabetes approval — but it does mean a multi-year gap between any first retatrutide approval and its statistically powered cardiovascular verdict is the expected sequence, not an unusual delay specific to this compound.

What Does This Mean for the FDA Approval Timeline?

Lilly's retatrutide NDA submission is targeted for Q4 2026, built on the TRIUMPH-1, TRIUMPH-4 and TRANSCEND-T2D-1 data already reported, plus whatever TRIUMPH-2 and TRIUMPH-3 add before filing closes — see our FDA approval timeline guide for the fuller regulatory picture. None of that filing package will include mature cardiovascular-outcomes data, because the dedicated CVOT will not have reported by then. This is a standard, FDA-accepted pathway: obesity and diabetes drugs are routinely approved on efficacy and short-term safety data with a post-marketing cardiovascular-outcomes commitment attached. For researchers evaluating retatrutide's published evidence base, the practical takeaway is sequencing rather than absence — TRIUMPH-2 and TRIUMPH-3 are the next data points due, and the dedicated outcomes trial is the one to watch on a timescale of years, not months.

What Should UK Researchers Take From This?

None of the trials described here change retatrutide's UK regulatory status: it remains an unlicensed, investigational compound with no MHRA marketing authorisation, and nothing in this trial-tracking summary constitutes a therapeutic or health claim. Velox Peptides supplies retatrutide strictly as an HPLC-verified in vitro research reagent, with no health or therapeutic claims made for it.

This compound is supplied as a research reagent only. It is not a medicine and has not been evaluated by the MHRA or FDA for use in our products. Not for human or veterinary use. See our Research Use Policy and MHRA Statement.

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