One of Eli Lilly’s buildings in San Diego, California on November 21, 2025.
Mike Blake | Reuters
Elie Lilly said Monday that its obesity pill, Foundayo, significantly reduced the severity of obstructive sleep apnea, the most common sleep-related breathing disorder, in obese patients in a late-stage trial.
The drugmaker plans to file for U.S. approval by the end of the year for the daily pill for moderate-to-severe obstructive sleep apnea, or OSA, in obese or overweight adults. The findings make the pill – which was launched in the US in April – one of several GLP-1 treatments showing promise in treating the disease.
OSA refers to interrupted breathing during sleep due to narrowing or blockage of the airways, which can cause drops in oxygen and increases in blood pressure that are associated with serious complications, such as hypertension, heart failure, and stroke. The disease affects nearly a billion adults worldwide, including 80 million people ages 20 and older in the United States, according to the National Council on Aging. Most have never been diagnosed, Lilly said in a statement.
Lilly’s blockbuster weight loss injection, Zepbound, became the first drug to gain U.S. approval for OSA in December 2024. Patients have limited treatment options outside of this drug and many use bulky machines that provide positive airway pressure, or PAP, to allow normal breathing.
“Foundayo is already making a difference for people living with obesity, and with plans to submit these results to the FDA by the end of the year, we may have the opportunity to help people living with OSA,” Dr. Thomas Seck, senior vice president of product development for Lilly Cardiometabolic Health, said in a statement.
Lilly Sleep Apnea Trial Results
The trial tested Foundayo in two independent studies, the first of which included 363 patients who were unable or unwilling to use PAP therapy. The second study included 349 people who had been taking PAP treatment for at least three months at the time of screening and who continued this treatment during the trial.
Patients in both studies who took Foundayo started with a low dose and gradually increased it at four-week intervals to different maximum doses.
Researchers specifically looked at how well the pill reduced the apnea-hypopnea index, or AHI, which records the number of times per hour a person’s breathing shows a restricted or completely blocked airway. The index is used to assess the severity of obstructive sleep apnea and the effectiveness of treatments for this condition.
According to the results, people who took Foundayo and did not use PAP treatment had an average of 21.1 fewer AHI events per hour at 52 weeks, compared to an average reduction of 4.8 per hour for placebo.
Foundayo also met the second endpoint of the trial in this group, leading to an overall AHI reduction of 43.8%, compared to a 6.3% decrease for placebo. Lilly said 31.5% of participants in the Foundayo group met criteria for remission or improvement of mild OSA.
Meanwhile, patients who received both Foundayo and PAP treatment had an average of 18.3 fewer AHI events per hour at 52 weeks, compared to an average reduction of 5.5 per hour for placebo.
Foundayo resulted in an overall reduction in AHI of approximately 27.5% in this group, compared to a 3% decrease for placebo. The company said 19.6% of Foundayo and PAP treatment participants also met criteria for remission or mild OSA.
Foundayo also reduced what is called sleep apnea-specific hypoxic burden – a measure of how deeply and for how long oxygen levels fall during sleep. This measure dropped 55.9% among people not using PAP therapy and 45.8% among those who did.
Lilly said the pill also helped patients lose about 11% of their weight in all groups at 52 weeks and helped reduce a marker of inflammation.
The company said the safety data and how patients tolerated Foundayo were generally consistent with previous trials of the pill.
About 12% of people on Foundayo who were not using the PAP treatment stopped treatment due to side effects, compared to 3.8% on the placebo. Meanwhile, 6.8% of people taking both Lilly’s pill and PAP stopped the drug due to side effects, compared to 0.6% in the placebo group.
The most common side effects were gastrointestinal, including nausea, diarrhea, constipation, and vomiting, and were generally mild to moderate in severity. This corresponds to other GLP-1 drugs.
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