Retatrutide at ACR Convergence 2026: How to Read the Knee Osteoarthritis Data

What Is Being Presented at ACR Convergence 2026?

Eli Lilly announced that new retatrutide (LY3437943) data will be presented at the American College of Rheumatology’s ACR Convergence 2026 meeting. As reported by RTTNews, the TRIUMPH-4 Phase 3 trial is scheduled for a plenary session on 8 November 2026, and TRIUMPH-1 for a poster session on 10 November 2026.[1] Both programmes include knee osteoarthritis (OA) pain outcomes in adults with obesity.

A note on sourcing: at the time of writing (10 November 2026) we could read only the scheduling announcement, not the abstracts or slides. This guide therefore does not report any new ACR figures. It summarises what Lilly had already disclosed, and explains how researchers can read OA pain endpoints critically when the full presentations are published. Retatrutide is covered more broadly in our retatrutide research guide.

What Did the TRIUMPH-4 Topline Report?

Lilly announced TRIUMPH-4 topline results on 11 December 2025: a randomised, double-blind, placebo-controlled Phase 3 trial of 445 adults with overweight or obesity and knee OA, run for 68 weeks, with retatrutide 9 mg and 12 mg arms against placebo.[2] The WOMAC pain score was a dual primary endpoint alongside body weight. Lilly reported that retatrutide 12 mg reduced WOMAC pain by 75.8% from baseline.[2] Our TRIUMPH-4 knee osteoarthritis guide covers the design and endpoints in detail, and the dysesthesia guide covers a separate adverse-event signal reported in that trial.

How Does the TRIUMPH-1 Osteoarthritis Sub-Study Differ?

TRIUMPH-1 (NCT05929066) was designed primarily around obesity outcomes, with OA as one of several “basket” sub-studies.[4][5] In the 574 participants with knee OA, the NEJM report described a WOMAC pain reduction of 73.1% (4.3 points) at 80 weeks with retatrutide 12 mg.[4] Our TRIUMPH-1 NEJM guide and basket trial design explainer describe the structure. The key distinction for readers is statistical: a sub-study within a trial powered for another primary endpoint supports different inferences than a trial built around the OA outcome.

The two durations differ, as do the designs, so the two WOMAC figures above should not be treated as a replicated result or ranked against each other.

How Should Researchers Read a WOMAC Pain Endpoint?

WOMAC pain is a patient-reported outcome, so several methodological points matter when the ACR presentations become available:

Absolute versus percentage change. A percentage reduction depends on the baseline score. Check baseline values, the absolute point change in each arm and the placebo arm’s change, since placebo response is typically substantial in OA pain trials.

Estimand. As in the cross-trial comparison guide, confirm whether a figure is a treatment-regimen estimand (all randomised participants) or an efficacy estimand (assuming adherence). They answer different questions.

Confounding by body weight. Because retatrutide also lowers body weight, pain change cannot be attributed to any single mechanism from these trials. Mediation analyses, if presented, would be exploratory.

Blinding and adverse events. Participants who experience gastrointestinal or sensory effects may infer their allocation, which can affect self-reported outcomes. Review the safety tables, including discontinuations, alongside efficacy.

Structural outcomes. Pain scores do not show whether joint structure changed. Imaging endpoints, if reported, would be a separate line of evidence.

What Is Retatrutide’s Regulatory Status?

Retatrutide has no marketing authorisation anywhere. Lilly has described a planned submission in the first quarter of 2027, covering obesity, knee OA pain and obstructive sleep apnoea.[3] Conference presentations are not regulatory decisions. Our FDA approval timeline guide tracks the submission pathway.

How Does Licensed Pharma Development Differ From Research-Use Compounds?

These trials are regulated clinical development by a licensed pharmaceutical sponsor, with registered protocols, ethics oversight and medical supervision of participants. Their results do not transfer to a laboratory reagent. Velox Peptides supplies retatrutide solely as an HPLC-verified in vitro research reagent and reports trial news only as third-party information for researchers. See the research-grade retatrutide page for specifications.

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.

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