Eli Lilly’s Foundayo adds late-stage sleep apnea data to obesity franchise

Eli Lilly said Foundayo significantly reduced the severity of obstructive sleep apnea in adults with obesity in two late-stage trials, creating the basis for a planned U.S. regulatory filing by the end of the year. The daily pill was introduced in the U.S. in April.

The studies assessed the apnea-hypopnea index, or AHI, which measures restricted or blocked breathing events per hour of sleep. One study enrolled 363 people unable or unwilling to use positive airway pressure, or PAP, therapy; the other enrolled 349 people already using PAP therapy for at least three months.

At 52 weeks, the results showed a separation from placebo in both treatment settings:

• Without PAP therapy, Foundayo reduced AHI by 21.1 events per hour, versus 4.8 for placebo, and cut AHI by 43.8%, versus 6.3%.
• Alongside PAP therapy, AHI fell by 18.3 events per hour, compared with 5.5 for placebo; the percentage reductions were 27.5% and 3%, respectively.

The results also covered oxygen loss during sleep, with the sleep apnea-specific hypoxic burden declining 55.9% in participants not using PAP and 45.8% in those using it.

Foundayo produced roughly 11% weight loss across the trial groups at 52 weeks, linking the sleep-apnea outcome to the drug’s obesity-treatment profile. The pill also reduced an inflammation marker, although the disclosed results do not specify its magnitude.

Clinical improvement was meaningful for a portion of participants, rather than universal. Among those not using PAP, 31.5% met the study criteria for remission or improvement to mild sleep apnea. The corresponding figure for people using PAP was 19.6%.

That distinction matters commercially. The prospective label seeks patients with moderate-to-severe obstructive sleep apnea who have obesity or are overweight, encompassing both people who do not use PAP and those who may use medication alongside it.

Safety and tolerability were generally consistent with prior Foundayo trials, with gastrointestinal effects—nausea, diarrhea, constipation and vomiting—the most common adverse events. Lilly characterized them as generally mild to moderate.

Discontinuations due to side effects were higher on active treatment. In the non-PAP study, around 12% of Foundayo recipients stopped treatment for side effects, compared with 3.8% on placebo. In the PAP study, the respective figures were 6.8% and 0.6%.

For an obesity medicine intended for long-term use, treatment persistence is an important part of the commercial equation. The efficacy results support an additional indication, while the discontinuation figures show that tolerability will remain relevant to how broadly the pill is used in practice.

Lilly already has a foothold in this indication: its injectable weight-loss drug Zepbound became the first medication approved in the U.S. for obstructive sleep apnea in December 2024. A Foundayo clearance would extend that position from an injectable treatment to a daily oral alternative.

Obstructive sleep apnea is associated with interrupted breathing, reduced oxygen levels and higher blood pressure, with potential complications including hypertension, heart failure and stroke. Lilly said many people remain undiagnosed, while PAP devices remain a common but burdensome treatment route.

An oral product with a sleep-apnea indication could therefore broaden the set of patients addressed by Lilly’s obesity portfolio and intensify competitive pressure across GLP-1-based therapies. It would also give prescribers another modality within the same company’s product range rather than relying solely on an injection.

At the time of writing, Eli Lilly shares traded at $1,388.645, up 2.56% from the prior close of $1,354. The stock traded between $1,364.5829 and $1,396.4445 during the session.

The next defined milestone is Lilly’s planned U.S. submission by year-end. The trial results establish a clinical rationale for that filing, but a regulatory decision and the final prescribing information would determine the exact scope of any sleep-apnea expansion.

For Lilly, the strategic value lies in converting obesity-driven weight loss into a broader set of disease-specific uses. The Foundayo data move that process forward while preserving the central competitive issue for the category: demonstrating durable clinical benefit with tolerability that supports continued treatment.