Eli Lilly drug tirzepatide, marketed as Zepbound for weight management, has results from two Phase 3 studies showing reductions in the breathing problems caused by obstructive sleep apnea. Lilly is now preparing regulatory submissions to add this indication to the drug’s label.

By Frank Vinluan

Sleep apnea could be the next new indication for an Eli Lilly drug that’s already a blockbuster seller in metabolic indications. The pharmaceutical giant has preliminary Phase 3 data showing that treatment with the drug reduced the breathing interruptions characteristic of the common sleep disorder.
With the positive data in hand, Lilly said it is now planning for regulatory submissions seeking to expand the label of tirzepatide, which is marketed as Mounjaro for type 2 diabetes and as Zepbound for weight management. Those submissions are expected in the middle of this year.
Obstructive sleep apnea (OSA) is the collapse or partial collapse of the upper airway, which interrupts breathing while a person sleeps. This can lead to hypopnea, which is reduced breathing that leads to insufficient oxygen intake, or apnea, a temporary cessation of breathing. There are no FDA-approved drugs for the condition, which is typically managed by medical devices. A continuous positive airway pressure (CPAP) machine and mask provides constant airflow to keep the airway open.
Tirzepatide is a peptide designed to bind to two receptors, GLP-1 and GIP. Activating these receptors regulates blood sugar, which supported the once-weekly injectable drug’s initial approval in type 2 diabetes. But this mechanism also contributes to feeling full so patients eat less. Last fall, the FDA approved tirzepatide for chronic weight management. Obesity is a risk factor for sleep apnea. Lilly’s OSA Phase 3 program set out to see if tirzepatide could also address sleep apnea.
OSA severity is measured according to a rating scale called the apnea-hypopnea index (AHI). On this scale, an AHI rating of 30 (30 or more breathing episodes per hour) is considered severe. Lilly evaluated tirzepatide’s effect on sleep apnea in two 52-week placebo-controlled Phase 3 studies enrolling non-diabetic patients who were obese. The main goal in both studies was to measure the change in AHI rating from baseline. The two secondary goals were measuring percent changes from baseline in AHI and body weight.
In the first trial, which enrolled adults who were not receiving CPAP therapy, tirzepatide treatment led to an average AHI reduction of 27.4 events per hour from baseline, Lilly reported. By comparison, the average reduction in the placebo arm was 4.8 events per hour. The percent change in AHI from baseline was a 55% reduction for the tirzepatide group versus 5 % for the placebo arm. On weight reduction, the tirzepatide group lost an average 18.1% of weight compared to 1.3% in the placebo arm.
The second Phase 3 study enrolled adults who were receiving CPAP therapy and planned to continue it. At 52 weeks, the study drug group showed an average reduction of 30.4 AHI events per hour compared to 6.0 events per hour for the placebo group. That translates to a 62.8% reduction for the Lilly drug arm versus 6.4% for placebo. The average weight reduction in tirzepatide-treated participants was 20.1% compared to 2.3% for the placebo group.
On safety, Lilly said side effects were similar to previous tests of the drug. The most commonly reported adverse events in the OSA studies were gastrointestinal-related and included diarrhea, nausea, and vomiting. All are known side effects of drugs in this class. Lilly characterized the side effects as mild to moderate in severity.
According to Lilly, an estimated 80 million people in the U.S. have OSA and more than 20 million have moderate-to-severe OSA. But most of those cases are undiagnosed and untreated, Jeff Emmick, senior vice president, product development, Lilly, said in a prepared statement.
“Addressing this unmet need head-on is critical, and while there are pharmaceutical treatments for the excessive sleepiness associated with OSA, tirzepatide has the potential to be the first pharmaceutical treatment for the underlying disease,” Emmick said.
The Phase 3 results will be submitted for publication in a peer-reviewed journal, Lilly said. The company will also present detailed results on June 21 during the scientific sessions meeting of the American Diabetes Association.
Tirzepatide sales under the Mounjaro name accounted for $5.1 billion in revenue in 2023. Zepbound was approved for chronic weight management last November. Lilly reported $175.8 million in fourth quarter 2023 sales for this indication. In a note sent to investors, Leerink Partners analyst David Risinger said that while there are no drugs specifically approved to treat OSA, standard of care pharmaceutical interventions include drugs that promote wakefulness, such as central nervous system stimulants and dopamine/norepinephrine reuptake inhibitors. The lack of an OSA-specific drug could lead to an FDA priority review for tirzepatide and potential approval in early 2025, Risinger said.
“The addition of OSA to the label could provide a meaningful entry point for access, and we note approximately 70% of OSA patients are obese,” he said.