Eli Lilly and Company has reported positive Phase 3 results from ATTAIN-OSA showing that Foundayo, or orforglipron, reduced obstructive sleep apnea severity in adults with obesity or overweight, supporting a planned U.S. regulatory submission by the end of 2026. In participants unable or unwilling to use positive airway pressure therapy, Foundayo reduced apnea-hypopnea index events by 21.1 per hour from an average baseline of 50.7 events per hour at 52 weeks, equivalent to a 43.8% reduction.
The results broaden the strategic importance of Foundayo only seven months after the U.S. Food and Drug Administration approved the once-daily oral GLP-1 receptor agonist for chronic weight management. Unlike many peptide-based incretin medicines, Foundayo is a small-molecule pill that can be taken without fasting or water restrictions, potentially giving Eli Lilly another route to expand pharmacological treatment of obesity-associated obstructive sleep apnea.
The opportunity is particularly interesting because Eli Lilly already owns the first FDA-approved drug for moderate-to-severe obstructive sleep apnea in adults with obesity, Zepbound. Foundayo therefore does not need to establish that pharmacological weight loss can influence OSA from scratch. It needs to demonstrate whether an oral GLP-1 can provide sufficient efficacy, convenience and tolerability to carve out a differentiated position beside Lilly’s own injectable tirzepatide franchise.
How much did Foundayo actually reduce obstructive sleep apnea in ATTAIN-OSA?
ATTAIN-OSA consisted of two independent, randomized, multicentre, double-blind, placebo-controlled Phase 3 studies running for 52 weeks. Study 1 enrolled 363 adults with moderate-to-severe OSA and obesity or overweight who were unable or unwilling to use PAP therapy, while Study 2 enrolled 349 participants already using PAP for at least three months who continued that treatment during the study.
Among participants not using PAP, Foundayo reduced AHI by 21.1 events per hour from an average baseline of 50.7, compared with a reduction of 4.3 events per hour with placebo. On a percentage basis, Foundayo produced a 43.8% reduction from baseline versus 6.3% with placebo, establishing a substantial treatment effect on the trial’s primary measure of sleep apnea severity.
The effect was also evident among participants continuing PAP therapy. Foundayo reduced AHI by 18.3 events per hour from an average baseline of 57.6, while placebo reduced AHI by 5.5 events per hour. The percentage reductions were 27.5% and 3.0%, respectively.
Those figures show that Foundayo affected breathing disturbances in both treatment settings, although the percentage reduction was larger among participants not using PAP. The two studies should not be treated as a direct comparison of whether Foundayo works better without PAP because they enrolled separate populations with different treatment circumstances.
Why do remission and mild-disease rates add important context to the AHI result?
Average changes in AHI establish the overall treatment effect, but they do not reveal how many individual patients moved into a substantially less severe disease category. In Study 1, 47.2% of participants receiving Foundayo achieved an AHI reduction of at least 50%, while 31.5% met the trial criteria for either remission or mild OSA.
The programme defined remission as an AHI below five events per hour. Mild disease required an AHI between five and fewer than 15 events per hour together with an Epworth Sleepiness Scale score of 10 or lower, indicating the absence of excessive daytime sleepiness under the study definition.
Among participants continuing PAP therapy, 33.7% achieved an AHI reduction of at least 50% and 19.6% reached remission or mild disease. These responder analyses help translate an average numerical reduction into a more clinically understandable outcome, although they do not mean that one-third of all future patients taking Foundayo can be expected to achieve the same result outside a controlled trial.
The distinction is important because OSA severity varies widely, and movement from severe to moderate disease is different from reaching remission. Regulators will examine the entire distribution of responses, baseline severity, adherence and missing-data handling rather than relying only on the most favourable responder percentage.
What does the 56% reduction in hypoxic burden add beyond counting breathing interruptions?
AHI counts how frequently breathing stops or becomes shallow during sleep, but it does not fully describe how deep or prolonged the accompanying oxygen reductions are. ATTAIN-OSA therefore also measured sleep apnea-specific hypoxic burden, which captures the magnitude and duration of oxygen desaturation associated with respiratory events.
In participants not using PAP, Foundayo reduced hypoxic burden by 81.4 percent-minutes per hour, or 55.9%, compared with an 18.3% reduction on placebo. Among PAP users, the respective reductions were 75.0 percent-minutes per hour, or 45.8%, with Foundayo and 17.0% with placebo.
That secondary result strengthens the physiological interpretation of the AHI findings because the treatment did more than reduce the counted frequency of respiratory disruptions. It also reduced the oxygen burden associated with those episodes, an important feature given the links between OSA, intermittent hypoxia and cardiovascular disease.
It would nevertheless be premature to convert those changes into a demonstrated reduction in heart attacks, strokes or other cardiovascular events. ATTAIN-OSA was designed principally to evaluate sleep apnea and related measures, not to establish cardiovascular outcomes.
How much of Foundayo’s OSA effect could be connected to weight loss?
Participants receiving Foundayo lost substantial weight over the 52-week trials. Those not using PAP lost an average of 11.5% of body weight, equivalent to about 28 pounds, compared with 1.8% for placebo. Participants using PAP lost 11.2%, or approximately 28.2 pounds, compared with 0.9% on placebo.
Weight loss can reduce the anatomical and mechanical factors contributing to upper-airway obstruction in people with obesity, making it biologically plausible that part of the OSA improvement reflects reduced body weight. Lilly has not established from the topline disclosure that Foundayo improves OSA through a weight-independent mechanism, so the results should not be interpreted as proving a separate direct respiratory pharmacological effect.
This is commercially relevant rather than a weakness in the treatment proposition. If an obesity medicine simultaneously lowers body weight and reduces sleep apnea severity, clinicians may value the combined outcome even if weight loss mediates much of the respiratory improvement.
The regulatory question is whether the overall clinical evidence supports a distinct OSA indication. Lilly plans to submit Foundayo for moderate-to-severe OSA in adults with obesity or overweight by the end of 2026, after which the FDA will determine whether ATTAIN-OSA supports expansion beyond the medicine’s existing weight-management label.
Why is Foundayo’s potential OSA label different from Zepbound’s existing approval?
Zepbound became the first FDA-approved medicine for moderate-to-severe obstructive sleep apnea in December 2024, specifically for adults with obesity. Foundayo is already approved for chronic weight management in adults with obesity or adults with overweight who have at least one weight-related comorbid condition, but it does not currently have an approved OSA indication.
Lilly describes the planned Foundayo OSA submission as covering adults with moderate-to-severe OSA and obesity or overweight. The exact authorised population cannot be assumed until the FDA reviews the application and determines the final indication, particularly because the wording would potentially differ from Zepbound’s existing obesity-only OSA label.
Route of administration creates the most obvious potential differentiation. Zepbound is a once-weekly injection acting on both GIP and GLP-1 receptors, while Foundayo is a once-daily oral small-molecule GLP-1 receptor agonist that does not require restrictions around meals or water.
That convenience could matter for patients who prefer tablets or are reluctant to initiate injectable therapy, but it does not automatically make Foundayo the better OSA treatment. Treatment choice would also depend on weight-loss magnitude, respiratory benefit, adverse effects, insurance coverage, price, individual preference and the broader metabolic needs of each eligible population.
Does Foundayo’s gastrointestinal tolerability create a meaningful trade-off?
Lilly reported that the overall safety and tolerability profile in ATTAIN-OSA was generally consistent with the earlier ACHIEVE and ATTAIN programmes. The most common adverse events were gastrointestinal and included nausea, diarrhoea, constipation, dyspepsia and vomiting, with most described as mild to moderate.
Treatment discontinuation provides a more consequential measure of tolerability. Among participants not using PAP, 12.2% of those taking Foundayo discontinued because of adverse events compared with 3.8% on placebo. Among PAP users, discontinuation rates were 6.8% with Foundayo and 0.6% with placebo.
The difference means the efficacy results must be considered alongside the fact that a meaningful minority of patients did not remain on therapy because of adverse events. For a medicine potentially used long term for obesity and OSA, persistence becomes commercially and clinically important because respiratory benefit is unlikely to matter if tolerability prevents continued treatment.
Foundayo’s approved U.S. prescribing information also contains the broader warnings and precautions applicable to its GLP-1 receptor agonist use. Expansion into OSA would increase the number of patients for whom clinicians must balance those established risks against the potential benefits of weight reduction and improved sleep-disordered breathing.
Why could an oral OSA drug matter when PAP remains a central treatment option?
PAP directly addresses airway obstruction during sleep and remains a core therapy for OSA, but long-term adherence can be difficult for some patients because treatment requires wearing a mask connected to a pressurised device while sleeping. ATTAIN-OSA deliberately included a study for adults unable or unwilling to use PAP, creating a population in which an effective pharmacological approach could address a practical treatment gap.
Foundayo should not be interpreted as having demonstrated that PAP is unnecessary or inferior. Study 2 specifically evaluated the medicine while participants continued PAP, suggesting Lilly sees pharmacological weight management as potentially complementary to established device therapy as well as relevant to those unable to use it.
An oral treatment may also alter how OSA is managed across specialties. Sleep physicians, obesity specialists, primary-care clinicians and cardiometabolic teams could increasingly share responsibility for patients whose sleep apnea is closely tied to excess weight.
That shift could expand the addressable market for pharmaceutical companies, but it also creates implementation questions around diagnosis, sleep studies, treatment monitoring and deciding when improvement in weight and AHI is sufficient to reconsider PAP requirements. Those clinical decisions require individual assessment rather than being inferred from the average ATTAIN-OSA results.
Why did Eli Lilly shares jump more than 4% as the OSA data were released?
Eli Lilly shares closed at $1,411.95 on November 9, up 4.28% from the previous session and close to their 52-week high of $1,453. The move coincided with the ATTAIN-OSA disclosure, although it would be too strong to attribute the entire increase to a single clinical programme given the number of other factors affecting a company with a market capitalisation of roughly $1.26 trillion.
Foundayo is already commercially important because it became available in the United States in April after an unusually rapid FDA review. Lilly has positioned the oral drug as a major expansion of its obesity franchise alongside Zepbound, while continuing to develop orforglipron across type 2 diabetes and several obesity-associated conditions.
OSA therefore represents an indication-extension opportunity rather than a binary first approval. If the FDA accepts the new indication, Lilly would control both an injectable dual-incretin medicine and an oral GLP-1 treatment for obesity-associated sleep apnea, giving it considerable flexibility across patient preferences and treatment settings.
The financial importance extends beyond one additional label. Lilly is building a cardiometabolic strategy in which obesity treatment increasingly acts as an entry point into multiple associated diseases, allowing one molecule to potentially generate value across weight management, sleep apnea, hypertension and other conditions.
Can Foundayo make OSA a second major market for oral GLP-1 therapy?
ATTAIN-OSA has answered the first pivotal question positively. Foundayo produced statistically significant reductions in apnea-hypopnea events in two randomized Phase 3 studies, including a 43.8% reduction among adults not using PAP and improvements in hypoxic burden, weight and several cardiovascular risk markers.
The programme has not established that Foundayo prevents cardiovascular events, permanently cures OSA or replaces PAP across the broad patient population. Adverse-event discontinuations, the need for long-term treatment and the relationship between weight loss and respiratory improvement will all remain relevant as regulators assess the data.
The commercial test is unusually interesting because Lilly will effectively compete with itself. Zepbound already has the first pharmaceutical OSA label in the United States, while Foundayo could offer a tablet for patients attracted by oral therapy or unwilling to use an injectable medicine.
A successful FDA expansion would therefore do more than add another indication to orforglipron. It would give Eli Lilly two fundamentally different incretin products targeting obesity-associated sleep apnea and deepen the shift of OSA treatment beyond devices alone. Whether Foundayo becomes a major OSA franchise will depend on regulatory approval, payer access and whether the convenience of a once-daily pill is compelling enough to translate its Phase 3 respiratory and weight-loss results into sustained real-world use.
