One of Eli Lilly’s buildings on November 21, 2025 in San Diego, California.
Mike Blake | Reuters
Eli Lilly On Monday, the company announced that its obesity drug 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 company plans to apply for U.S. approval by the end of the year for a daily pill to treat moderate to severe obstructive sleep apnea (OSA) in obese or overweight adults. The results make the pill, which went on sale in the U.S. in April, one of several GLP-1 treatments showing promise for treating the condition.
OSA refers to interruptions in breathing during sleep due to narrowing or obstruction of the airways. This causes a drop in oxygen and an increase in blood pressure, which can lead to serious complications such as high blood pressure, heart failure, and stroke. The disease affects nearly 1 billion adults worldwide, including 80 million people age 20 and older in the United States, according to the National Council on Aging. Most have never been diagnosed, Lilly said in the release.
Lilly’s blockbuster weight-loss injectable Zepbound became the first drug to win approval for OSA in the U.S. in December 2024. Treatment options for patients are limited beyond the drug, and many rely on cumbersome machines that provide positive airway pressure (PAP) to allow normal breathing.
“Foundayo is already making a difference for people living with obesity, and with our plans to submit these results to the FDA by the end of the year, we may have an opportunity to help people living with OSA,” said Dr. Thomas Seck, senior vice president of product development at Lilly Cardiometabolic Health, in a release.
Lily’s sleep apnea test results
This trial validated Foundayo in two independent studies. The original study included 363 patients who were unable or unwilling to use PAP therapy. The second study included 349 people who had been on PAP therapy for at least 3 months at screening and continued their treatment for the duration of the study.
Patients taking Foundayo in both studies started at a low dose and gradually increased to different maximum doses at four-week intervals.
The researchers specifically looked at how much the pills lowered the so-called apnea-hypopnea index (AHI), which records the number of times per hour that a person’s breathing shows airway restriction or complete obstruction. This index is used to assess the severity of obstructive sleep apnea and the effectiveness of treatment for the condition.
Results showed that people who took Foundayo and did not use PAP therapy had an average reduction of 21.1 AHI events per hour at week 52, compared with an average reduction of 4.8 events per hour in the placebo group.
Foundayo also met the study’s second goal in that group, reducing overall AHI by 43.8% compared to 6.3% with placebo. Lilly said 31.5% of participants in the Foundayo group met criteria for remission or improvement in mild OSA.
Meanwhile, patients receiving both Foundayo and PAP therapy had an average reduction of 18.3 AHI events per hour at week 52, compared with an average reduction of 5.5 events per hour in the placebo group.
Foundayo produced an overall AHI reduction of about 27.5% in that group, compared to a 3% reduction with placebo. The company said 19.6% of participants on Foundayo and PAP therapy also met criteria for remission or mild OSA.
Foundayo also reduced what is known as hypoxic burden, a measure of how deeply and for how long oxygen levels drop during sleep, which is unique to sleep apnea. This metric decreased by 55.9% for those not using PAP therapy and by 45.8% for those using it.
Lilly said the pill reduced patient weight by about 11% across the group at 52 weeks and also helped lower inflammatory markers.
The company said the safety data and patient tolerability of Foundayo were generally consistent with previous studies of the pill.
Approximately 12% of people receiving Foundayo without PAP therapy discontinued due to side effects, compared with 3.8% of those receiving placebo. Meanwhile, 6.8% of the group taking both Lilly’s Pill and PAP discontinued the drug due to side effects, compared to 0.6% of 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 is consistent with other GLP-1 therapeutics.
