Sleep apnea: TRIUMPH-1-OSA and TRIUMPH-2-OSA
The NEJM paper, published online October 21, reports two double-blind, placebo-controlled phase 3 trials nested inside the larger TRIUMPH-1 and TRIUMPH-2 studies. Adults with moderate-to-severe obstructive sleep apnea and a BMI of at least 27 were randomized to weekly retatrutide 4, 9 or 12 mg or placebo. TRIUMPH-1-OSA enrolled 243 people without type 2 diabetes and TRIUMPH-2-OSA enrolled 448 with it. Their apnea-hypopnea index (AHI), the average number of breathing pauses and shallow-breathing episodes per hour of sleep, averaged 58.6 and 55.9 at the start.[1]
At 80 weeks, measured against placebo:[1]
- Without diabetes (TRIUMPH-1-OSA): AHI changed by −22.9, −34.3 and −31.7 events per hour on 4, 9 and 12 mg, against −9.9 on placebo. The differences from placebo were −13.0 (95% CI −23.0 to −3.0), −24.4 (−34.1 to −14.7) and −21.9 (−32.2 to −11.5).
- With type 2 diabetes (TRIUMPH-2-OSA): AHI changed by −19.2, −24.7 and −25.4 events per hour, against −10.3 on placebo. The differences from placebo were −8.9 (95% CI −15.9 to −2.0), −14.4 (−21.6 to −7.2) and −15.1 (−22.5 to −7.7).
- How these were counted: the figures above use the trials’ hybrid-treatment estimand. The intention-to-treat differences were close, for example −24.7 events per hour on 9 mg in TRIUMPH-1-OSA.
- Weight: fell 12.5% to 22.2% on retatrutide in TRIUMPH-1-OSA and 12.1% to 18.5% in TRIUMPH-2-OSA, against 4.8% and 5.6% on placebo.
- Side effects: the most common were gastrointestinal.
The trials were funded by Lilly, and six of the twelve named authors list Eli Lilly as their affiliation.[1] The journal’s November 5 issue also carries an editorial by Rosen and Ingelfinger on retatrutide in obesity, osteoarthritis and sleep apnea.[2] For how these numbers sit beside the treatment already approved for sleep apnea, see our patient guide to GLP-1 drugs and sleep apnea.
Knee osteoarthritis: TRIUMPH-4
In a November 5 release ahead of a plenary presentation at ACR Convergence 2026 in Orlando, Lilly said that in the 68-week TRIUMPH-4 trial retatrutide reduced knee osteoarthritis pain by up to an average of 4.5 points (75.8%) from an average baseline of 6.0 on the WOMAC pain subscale. More than 1 in 8 people treated with retatrutide had no knee pain at the end of the trial.[3] These are company figures from a conference abstract. The release gives no placebo result, and the full trial has not been published.
The closest approved-drug evidence is semaglutide’s STEP 9 trial, covered in our review of GLP-1 drugs for knee osteoarthritis pain.
Where retatrutide stands
Lilly has said its data package covers obesity, sleep apnea and knee osteoarthritis pain and that it plans to file with the FDA in early 2027; our report on the filing timeline has the details. Our running summary of the TRIUMPH phase 3 program now includes both sets of results. Lilly says retatrutide cannot legally be sold or marketed for human use, so products sold online under that name are not approved drugs.[3]