Indianapolis, Indiana, United States, November 9, 2026
Eli Lilly and Company has announced positive results from its Phase III ATTAIN-OSA clinical trial program, demonstrating that Foundayo (orforglipron) significantly reduced the severity of obstructive sleep apnea (OSA) in adults with overweight or obesity. The investigational use was evaluated in participants with moderate-to-severe OSA, both with and without positive airway pressure (PAP) therapy. At 52 weeks, the oral treatment met the primary endpoint in both study populations, showing statistically significant reductions in the apnea-hypopnea index (AHI), a standard measure of sleep apnea severity. The findings were presented at the American Heart Association (AHA) Scientific Sessions 2026 and simultaneously published in the Journal of the American Medical Association (JAMA). According to Lilly, Foundayo reduced breathing interruptions during sleep by up to an average of 43.8% and improved additional measures associated with oxygen levels, body weight and cardiovascular risk. The results highlight the potential of oral GLP-1 therapy to address obstructive sleep apnea alongside weight management, expanding the clinical development opportunities for orforglipron beyond its existing weight-management indication.
Phase III ATTAIN-OSA Trial Achieves Primary Endpoint
The ATTAIN-OSA program consisted of two independent, randomized, double-blind, placebo-controlled Phase III studies involving approximately 712 adults with moderate-to-severe obstructive sleep apnea and overweight or obesity. One study evaluated participants who were unable or unwilling to use PAP therapy, while the second involved participants who had been using PAP therapy for at least three months. Both studies assessed the effectiveness and safety of once-daily oral Foundayo over 52 weeks. The primary endpoint measured changes in the apnea-hypopnea index, which calculates the number of breathing interruptions or shallow-breathing episodes occurring per hour during sleep. In participants not using PAP therapy, Foundayo reduced AHI by an average of 21.1 events per hour, representing a 43.8% reduction from baseline. In participants using PAP therapy, the treatment reduced AHI by 18.3 events per hour, representing a 27.5% reduction. Both comparisons demonstrated statistically significant improvements over placebo. Additionally, 31.5% of participants not using PAP therapy achieved remission or mild disease, compared with 19.6% among participants using PAP therapy. These findings demonstrate that the treatment produced meaningful improvements in sleep apnea severity across both study populations. The results also provide further evidence supporting the investigation of weight-related metabolic therapies in patients experiencing sleep-disordered breathing.
Foundayo Improves Oxygen Levels and Cardiovascular Risk Factors
Beyond reducing breathing interruptions, the clinical program evaluated sleep apnea-specific hypoxic burden, a measure of how deeply and for how long oxygen levels decrease during sleep. In participants not using PAP therapy, Foundayo reduced hypoxic burden by 55.9%, while participants using PAP therapy experienced a 45.8% reduction. These improvements are important because repeated oxygen drops during sleep can contribute to cardiovascular stress and are associated with conditions such as hypertension, heart failure, atrial fibrillation and coronary artery disease. The treatment also demonstrated substantial weight reduction during the 52-week study period. Participants not using PAP therapy experienced an average weight reduction of 11.5%, equivalent to approximately 28 pounds, while those using PAP therapy lost approximately 11.2%, or 28.2 pounds. In addition, Foundayo improved certain cardiovascular risk markers, including high-sensitivity C-reactive protein (hsCRP), an indicator of inflammation, and systolic blood pressure. The company reported average hsCRP reductions of 48.9% and 38.6% in the two study populations, respectively. Systolic blood pressure also decreased by 8.6 mmHg in participants not using PAP therapy and 7.3 mmHg in those using PAP therapy. These findings suggest that Foundayo may provide benefits across multiple interconnected metabolic and cardiovascular health measures, although the trial was not designed to establish reductions in long-term cardiovascular events.
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Safety Profile and Regulatory Development Plans
Foundayo, also known by its generic name orforglipron, is a once-daily oral small-molecule glucagon-like peptide-1 (GLP-1) receptor agonist developed by Eli Lilly. Unlike injectable GLP-1 medicines, the oral formulation is designed to be taken without fasting or specific water restrictions. Its mechanism involves activating GLP-1 receptors, which regulate appetite, food intake and glucose metabolism. The safety findings from ATTAIN-OSA were generally consistent with those observed in Lilly’s earlier ACHIEVE and ATTAIN clinical programs. Common adverse events were primarily gastrointestinal and included nausea, diarrhea, constipation, dyspepsia and vomiting. Treatment discontinuations due to adverse events were higher among Foundayo recipients than placebo recipients, highlighting the importance of continued safety evaluation. Based on the positive Phase III findings, Lilly plans to submit Foundayo to the U.S. Food and Drug Administration (FDA) for moderate-to-severe obstructive sleep apnea in adults with overweight or obesity by the end of 2026. The proposed sleep apnea indication remains subject to regulatory review and has not yet been approved. Foundayo already has an approved use for weight management in the United States, but its potential application in OSA represents a separate regulatory development. The ATTAIN-OSA findings represent an important milestone in Lilly’s clinical development program for orforglipron. By demonstrating improvements in breathing interruptions, oxygen levels and body weight, the study provides encouraging evidence for the potential role of oral GLP-1 therapy in obstructive sleep apnea. The planned FDA submission will be an important next step in determining whether Foundayo can expand its therapeutic role into sleep-related respiratory disorders.
Source: Eli Lilly press release
