TRIUMPH-1 Published in NEJM as Lilly Restates Its 2027 Filing Plan (September 29, 2026)

The TRIUMPH-1 NEJM paper came out on September 29, 2026, and its headline result is 25.0% average weight loss on retatrutide 12 mg against 3.9% on placebo after 80 weeks, counting everyone who was randomized. It's the first full journal report for any TRIUMPH trial. The primary source is Jastreboff and colleagues in The New England Journal of Medicine; the same day, Lilly restated that it planned to submit retatrutide to the FDA in the first quarter of 2027.

This page covers what the paper adds to Lilly's May topline and what Lilly said about filing that day. The full trial, dose by dose, is on the TRIUMPH-1 page.

What the TRIUMPH-1 NEJM paper reports

TRIUMPH-1 is a randomized, double-blind Phase 3 trial: 2,339 adults with obesity, or overweight plus a weight-related condition, and no diabetes, on 4 mg, 9 mg or 12 mg of retatrutide or placebo for 80 weeks. NEJM's primary weight result uses the treatment-regimen estimand, which the paper describes as intention-to-treat (ITT).

On that measure, weight fell 17.6% on 4 mg, 23.7% on 9 mg and 25.0% on 12 mg, against 3.9% on placebo. The differences from placebo for 9 mg and 12 mg were 19.8 and 21.0 percentage points (P < 0.001). These match the treatment-regimen figures in Lilly's May release, so nothing changed. What changed is that a journal has now checked them.

Two estimands, one trial

The efficacy estimand asks what happens if everyone stays on the drug. The treatment-regimen estimand counts everyone randomized, including people who stopped. Our read: if you quote TRIUMPH-1 next to NEJM, quote 25.0%. The 28.3% belongs with "Lilly reported" and the words "efficacy estimand."

The knee and sleep apnea groups

TRIUMPH-1 had two basket groups inside it, and the paper gives every arm with placebo, where Lilly's June release gave "up to" values. In 574 people with knee osteoarthritis, WOMAC pain fell 3.2, 3.5 and 3.6 points on 4, 9 and 12 mg against 1.9 on placebo (the abstract describes the scale as ranging "from 1 to 10"). In 243 people with sleep apnea, apnea events fell 22.9, 34.3 and 31.7 an hour against 9.9. Both use a hybrid-treatment estimand.

On safety, the abstract says only: "The most common adverse events were gastrointestinal." It gives no serious adverse event rate, and we haven't read the full text. The registry record for TRIUMPH-1 now lists this paper and the October sleep apnea paper as references.

Lilly's 2027 filing plan, as stated that day

The filing plan came in Lilly's September 29 release on TRIUMPH-2, and it's still Lilly's latest statement on timing: the October 28 release and the October 29 earnings filing give none. Here is where things stand.

Lilly last said, on September 29, 2026, that it plans to submit retatrutide to the FDA in the first quarter of 2027 as a Biologics License Application (BLA). On October 2, 2026, the FDA decided that retatrutide is a drug, not a biological product, so an application would need to be filed under section 505 of the Federal Food, Drug, and Cosmetic Act. Lilly's appeal on that question is pending in the Seventh Circuit, and we found no ruling as of October 31, 2026. The October 2 news page has the details.

What comes next

The FDA approval page covers the review that starts once Lilly files, and the release date page works through when a 2027 filing could reach pharmacies. Until then no approved version exists, and anything listed as retatrutide for sale online isn't what TRIUMPH-1 tested. The next big obesity readout is TRIUMPH-5, against tirzepatide.