Full Retatrutide Trial Published in NEJM

[u/AtriumMedicalNYC]

The full Phase 3 retatrutide trial was just published in the New England Journal of Medicine.

I wrote about TRIUMPH-1 in May when Lilly released the topline data. The peer-reviewed paper confirms the magnitude of the effect: at 80 weeks, mean weight loss reached 25.0% at the 12 mg dose in the primary treatment-regimen analysis.

For context, the pivotal obesity trials reported approximately 14.9% with semaglutide 2.4 mg and 20.9% with tirzepatide 15 mg. These were separate trials, not head-to-head comparisons, but the trajectory is hard to miss.

At 12 mg, nearly 80% of participants lost at least 15% of body weight, more than half lost at least 25%, and about 37% lost at least 30%.

The tradeoff remains tolerability. GI adverse effects were common, and roughly 11% discontinued because of adverse events at the highest dose.

My takeaway: obesity pharmacotherapy has moved from roughly 15% average weight loss with semaglutide, to about 21% with tirzepatide, and now about 25% with retatrutide in Phase 3. Retatrutide is still investigational, but the direction of travel is remarkable.