Lilly's Foundayo pill cuts sleep apnea events 43.8% in two trials, and 12% quit on side effects

Eli Lilly said Monday that Foundayo, its once-daily obesity pill, significantly reduced the severity of obstructive sleep apnea in two late-stage trials, and that it plans to file with the FDA for moderate-to-severe cases in adults with obesity or overweight by the end of the year, CNBC reported. Reuters carried the same results under the headline "Lilly's weight-loss pill improves sleep apnea in late-stage study."

The results, with the placebo taken out

The studies used the apnea-hypopnea index (AHI), the count of breathing interruptions per hour of sleep. One trial enrolled 363 people who could not or would not use a CPAP machine. The other enrolled 349 who stayed on CPAP during the trial. All figures below are at 52 weeks, from the CNBC account of Lilly's release.

Our arithmetic: subtract the placebo and the pill's own effect is about 16.3 fewer events an hour without CPAP and 12.8 with it, or 37.5 and 24.5 percentage points on the overall reduction. Patients also lost roughly 11% of their weight across groups, and a measure of nighttime oxygen deprivation, the sleep apnea-specific hypoxic burden, fell 55.9% without CPAP and 45.8% with it.

What the headline leaves out

The treatment is not for everyone who tries it. About 12% of the no-CPAP Foundayo group stopped because of side effects, against 3.8% on placebo, a gap of roughly eight points. In the CPAP group the gap was 6.8% versus 0.6%. Lilly described the side effects as mostly gastrointestinal (nausea, diarrhea, constipation, vomiting), generally mild to moderate and in line with earlier Foundayo trials.

Also note what "remission or mild OSA" means: 31.5% reached it without CPAP, so roughly two in three did not. For the rest, this is a reduction in severity, not a cure.

Who this touches

The CNBC report notes that Zepbound, Lilly's injection, became the first drug approved in the U.S. for sleep apnea in December 2024, and that the condition affects about 80 million U.S. adults aged 20 and over, per the National Council on Aging, most of them undiagnosed. A pill would add a second route for patients who dislike injections. For the sleep clinics, dental-device makers and home-medical-equipment suppliers that serve CPAP users, the near-term change is nil: the drug still needs FDA review, and the trial shows it helping on top of CPAP as well as instead of it.

Lilly shares traded at $1,393.93 at 11:26 a.m. Eastern, up 2.95% on the day, with a market value of about $1.31 trillion, according to Nasdaq. We could not tie the move to this announcement from the sources we read. For earlier Lilly trial coverage, see our look at EloraTZP. Lilly's filings are on SEC EDGAR.

Sources: CNBC; Reuters (headline); Nasdaq.com quotes. Trial figures are company-reported and have not been peer reviewed in the reports we read. This is market information, not investment advice.