News · Trial readout · August 19, 2025
All four TRIUMPH pivotal trials reach full enrollment
Eli Lilly has confirmed that all four TRIUMPH-program pivotal trials — TRIUMPH-1 through TRIUMPH-4 — have completed enrollment, setting the stage for sequential 2026 readouts.
The four trials, at a glance
The TRIUMPH studies share a common template — randomized, double-blind, placebo-controlled, with multiple maintenance-dose arms — and each tests retatrutide in a different at-risk population:
- TRIUMPH-1 — adults with obesity without diabetes; ≈ 2,300 participants; 76 weeks; primary endpoint mean percent change in body weight. Topline guided for 2026.
- TRIUMPH-2 — adults with obesity and type 2 diabetes; ≈ 1,800 participants; 72 weeks; co-primary focus on weight and HbA1c. Topline guided for 2026.
- TRIUMPH-3 — adults with obesity and established cardiovascular disease; ≈ 1,800 participants; 76 weeks. Topline expected 2026 – 2027.
- TRIUMPH-4 — adults with obesity and knee osteoarthritis; ≈ 600 participants; 68 weeks; weight and pain-score endpoints. Topline expected 2026 – 2027.
That is approximately 6,500 participants in aggregate across the four studies — the dataset Lilly will use to seek US and EU approval. See the clinical trials page for full design detail.
Why full enrollment matters
Recruitment is the least predictable phase of a pivotal program. With enrollment complete across all four trials, the largest source of schedule risk is removed: readout timing is now driven by treatment duration, data lock, and analysis — not by how fast sites can randomize participants.
It also fixes the readout sequence. TRIUMPH-1 and TRIUMPH-2, with 2026 guidance, will define the efficacy narrative; TRIUMPH-3 and TRIUMPH-4, expected 2026 – 2027, extend it into cardiovascular and osteoarthritis populations. Lilly has guided to topline readouts beginning in 2026.
What enrollment completion does not tell us
- Nothing about efficacy. Enrollment is a logistics milestone. No topline efficacy or safety data accompanied the confirmation.
- Nothing about retention. Discontinuation and dropout rates only become visible at readout — and they matter, given the GI-driven withdrawal rates seen in Phase 2.
- No guaranteed calendar. Event-driven elements of the program (particularly cardiovascular outcomes follow-up) can still shift individual readout windows.
Retatrutide remains investigational; no regulator has approved it. The next milestone that changes the evidence base is the first TRIUMPH topline readout — see how to read the TRIUMPH-1 readout when it lands.