Clinical Background on OSA OSA is a prevalent disorder, with roughly 1 in 5 adults estimated to have at least mild OSA and 1 in 15 estimated to have at least moderate OSA. Furthermore, OSA causes a number of adverse cardiovascular, neurocognitive, and daytime functional consequences. As a result, understanding the pathophysiology and developing treatments is a major public health goal. Unfortunately, only approximately 50% of patients tolerate the main therapy for OSA, Continuous Positive Airway Pressure (CPAP). Therefore, new therapeutic approaches are clearly needed.
OSA is caused by collapse of the pharyngeal airway during sleep due to the sleep state-related loss of pharyngeal muscle activity. High nasal resistance can contribute to pharyngeal collapse as well by increasing the suction pressure downstream in the velo- and oropharynx. In fact, a recent study in 139 patients with chronic rhinosinusitis (CRS) demonstrated an extremely high prevalence of OSA (65% of the CRS patients had OSA compared to a prevalence in the normal population of 5-15%). Therefore, a drug that reduces nasal congestion and pharyngeal edema, such as dupilumab, could potentially improve OSA in some patients.
Immunologic Background on OSA and role of Type 2 inflammation Indeed, preliminary patient-reported outcomes data from early clinical trials with dupilumab have shown that dupilumab treatment of patients with sinus disease reduces reports of nocturnal awakenings, as well as sleep-related outcomes on the SinoNasal Outcome Test (SNOT-22). In addition to the known effects of dupilumab on the reduction of nasal polyp size/volume, there is ample evidence to propose that the specific anti-inflammatory effects achieved with IL-4Rα blockade will be particularly relevant to a potential therapeutic effect of dupilumab on OSA in patients with comorbid CRS. There are a number of Type 2 inflammatory markers that are increased in patients with CRS and OSA, which taken together suggest that OSA in these patients is truly an inflammatory disease, and not solely a disease of abnormal anatomy. Serum IL-4 levels are elevated in patients with rhinitis and OSA, and those levels are negatively correlated with time spent in REM sleep. Furthermore, two inflammatory markers of mast cell activation, urinary leukotriene E4 and urinary prostaglandin D2, are also known to be elevated in OSA, likely due to the increased chronic mast cell stimulation afforded by the high circulating IL-4 levels. Strikingly, both urinary leukotriene E4 and prostaglandin D2 levels correlate with OSA severity, as measured by either percentage of overnight time spent with SaO2 \<90% or the apnea/hypopnea index (AHI).
There is additional clinical evidence to suggest that OSA may be more than "just" an anatomic disease. Although endoscopic sinus surgery to remove inflamed sinus tissue in patients with OSA and CRS does improve OSA symptoms, non-surgical anti-inflammatory treatments, including intranasal steroids and leukotriene modification with montelukast, have also been found to improve OSA symptoms and decrease the AHI.
Given these immunological findings, the investigators suspect that extensive Type 2 inflammation is a major contributing factor for patients with CRS and OSA, and that IL-4Rα blockade will be a powerful therapeutic tool in sleep apnea. In combination with the preliminary patient-reported outcomes data suggesting that dupilumab improves sleep quality, the investigators feel confident that dupilumab will successfully provide a clinically-quantifiable therapeutic improvement on the severity of OSA in patients with CRS and OSA. As there are currently no FDA-approved medications for the treatment of OSA, and 65% of all patients with CRS suffer from OSA, the investigators feel as though positive results from this pilot trial would be a powerful step towards providing a new biologic therapy to an underserved medical population.
