U of T Prof's Research Advances Sleep Apnea Drug

A drug targeting two key pathways identified by University of Toronto professor Richard Horner has shown promising results in treating obstructive sleep apnea. In a phase 3 clinical trial published in the *American Journal of Respiratory and Critical Care Medicine*, patients with mild to severe sleep apnea who received the drug—developed by Apnimed in Cambridge, Massachusetts—experienced less airway obstruction and higher oxygen levels compared to those given a placebo. Horner, a professor of medicine and physiology at U of T’s Temerty Faculty of Medicine, has spent three decades studying the nerves and muscles controlling breathing during sleep. His work uncovered critical mechanisms behind sleep apnea, where upper airway muscles repeatedly collapse, disrupting breathing and leading to long-term health risks like high blood pressure and heart disease. The condition affects over 1.6 billion adults worldwide, yet fewer than 10% of Canadians with sleep apnea have a formal diagnosis, despite estimates suggesting one in four Canadians may have it, according to a 2024 study in the *Canadian Journal of Public Health*. Horner’s research began in the early 1990s at the University of London and later expanded at U of T, where he pioneered models to study natural sleep and breathing circuits. In 2006, Horner’s team identified noradrenaline as a key neurotransmitter activating the tongue muscle during wakefulness and certain sleep phases. The tongue plays a vital role in maintaining airflow, and this discovery helped pinpoint targets for drug development. The phase 3 trial results mark a significant step toward improving treatment options for a disorder that often goes undiagnosed but severely impacts patients’ quality of life.