Two parallel phase III trials testing the once-weekly injectable retatrutide met their primary endpoint in obstructive sleep apnea, with meaningful reductions in the apnea-hypopnea index over 80 weeks. In TRIUMPH-1-OSA, which excluded type 2 diabetes, the 9 mg and 12 mg doses cut AHI by 24.4 and 21.9 events per hour more than placebo. In TRIUMPH-2-OSA, enrolling patients with type 2 diabetes, the reductions versus placebo were 14.4 and 15.1 events per hour. The findings were published in the New England Journal of Medicine and presented at the Congress of the European Sleep Research Society.
Weight loss paralleled the effect on breathing: mean reductions were 12.5% to 22.2% in the trial without diabetes and 12.1% to 18.5% in the trial with diabetes, compared with 4.8% and 5.6% for placebo. OSA remission, defined as an AHI below 5 events per hour or 5 to 14 with improved sleepiness, was reached in up to 51.6% of treated participants in the first trial and 39.5% in the second, versus about 12.5% in the placebo groups.
The results look similar to tirzepatide, the first drug approved for OSA, which reduced AHI by 20.0 to 23.8 events per hour in the SURMOUNT-OSA program. An expert cited in the report said retatrutide was not clearly superior to tirzepatide, while another noted that having more options matters because CPAP, the gold standard, is not tolerated by everyone. The most common adverse events were gastrointestinal, consistent with the broader retatrutide trials.