Retatrutide Phase 3 results: TRIUMPH-1 read out on 21 May 2026.

The Phase 2 result that set the bar

Retatrutide is a single molecule that agonizes three receptors: GLP-1, GIP and glucagon. The GLP-1 and GIP arms follow the template that tirzepatide established. The glucagon arm is the addition, studied for its effect on energy expenditure rather than appetite alone. That third mechanism is the whole argument for the compound.

The Phase 2 data, published by Jastreboff et al. in NEJM in 2023, reported a 24.2% mean weight reduction at 48 weeks at the highest dose. For context, tirzepatide reached 22.5% at 72 weeks in SURMOUNT-1 and semaglutide reached 14.9% at 68 weeks in STEP 1. Retatrutide got further, faster, in a smaller trial. Phase 2 numbers are not Phase 3 numbers, and everyone in the field knows compounds can lose ground when the sample size grows. But 24.2% was enough to make TRIUMPH the most watched obesity program in development.

Where TRIUMPH stands in 2026

TRIUMPH is Eli Lilly's Phase 3 program for retatrutide, and 4 of its trials have read out: TRIUMPH-4 on 11 December 2025, TRIUMPH-1 on 21 May 2026, TRIUMPH-2 on 23 July 2026 and TRIUMPH-3 on 23 July 2026. Phase 3 obesity trials run long by design, so results arrive in stages as each study completes rather than as one announcement.

In TRIUMPH-1, a Phase 3 trial of 80 weeks in adults with obesity, or overweight with at least one weight-related condition, without diabetes, the highest dose arm lost 28.3% of body weight, against 2.2% on placebo. That is now the headline figure for the compound; the Phase 2 number above is the history behind it. The figures are from Lilly's TRIUMPH-1 release.

The same trial reported gastrointestinal side effects as the most common. Across its three dose arms, nausea was reported by 28.6 to 42.4% of participants, diarrhoea by 25.2 to 34.1% and constipation by 23.8 to 26.1%. Discontinuation for adverse events was 4.1% at 4mg, 6.9% at 9mg, 11.3% at 12mg, against 4.9% on placebo. TRIUMPH-4 also reported dysesthesia, an abnormal skin sensation not seen in the Phase 2 literature, in 8.8% at 9mg and 20.9% at 12mg, against 0.7% on placebo (TRIUMPH-4). Lilly described these events as generally mild and rarely leading to discontinuation.

Still running: TRIUMPH-5, head to head against tirzepatide. Active, not recruiting. TRIUMPH-6, weight maintenance. TRIUMPH-OUTCOMES, cardiovascular and renal outcomes, approximately 10,000 participants. Lilly plans to submit a Biologics License Application to the FDA in Q1 2027. No regulator has approved retatrutide. No FDA Philippines registration. No branded product exists in any market.

What approval would mean for the research market

If regulators approve retatrutide after that filing, the pharmaceutical version will arrive as a branded injectable at branded prices, and Philippine availability will lag Western launches the way it did for tirzepatide. Approval also tends to raise, not lower, interest in the research-use-only market, because published Phase 3 data gives researchers a much richer literature to work against.

Today, before any approval, retatrutide exists in the Philippines only as a research-use-only compound. The Primara Labs retatrutide Philippines listing is a 20mg vial in Metro Manila cold storage at ₱3,775, or ₱3,390 with 10% off, with same-day dispatch on verified orders placed before 12 noon. Every vial carries a printed batch number. The full local picture is in the retatrutide price guide.

Supplied for laboratory research use only. Not for human consumption. Nothing on this page is medical advice.