Sustained efficacy of mepolizumab in patients with severe chronic rhinosinusitis with nasal polyps: SYNAPSE 24‐week treatment‐free follow‐up

Abstract Background In the 52‐week Phase III SYNAPSE study, mepolizumab given every 4 weeks (100 mg subcutaneously) reduced nasal polyp (NP) size, improved symptoms and quality of life (QoL), and reduced corticosteroid use and number of sinus surgeries in patients with severe chronic rhinosinusitis with nasal polyps (CRSwNP), versus placebo. Because the durability of mepolizumab's efficacy after discontinuation is poorly understood in CRSwNP, the efficacy of mepolizumab after discontinuation was analyzed in severe CRSwNP, over a 24‐week follow‐up. Methods Changes from SYNAPSE baseline to end of treatment (week 52) and end of follow‐up (week 76) were assessed for total endoscopic NP score, nasal obstruction and overall symptoms visual analog scale scores, and 22‐item Sino‐Nasal Outcome Test score. Time to first sinus surgery, time to first corticosteroid use, and geometric mean blood eosinophil counts (BECs) were also assessed. Results Among 134 follow‐up patients, clinical improvements observed with mepolizumab versus placebo were partially evident 24 weeks after discontinuation despite BEC returning to baseline. The mean (95% confidence interval [CI]) change from baseline in NP score (week 52: −1.3 [1.8 to −0.9] vs. −0.3 [−0.6 to 0.1]; week 76: −1.2 [−1.6 to −0.7] vs. −0.1 [−0.5 to 0.3]) and the proportion of patients having sinus surgery (week 52: 4% vs. 25%; week 76: 9% vs. 31%) remained substantially improved with mepolizumab versus placebo. Mepolizumab‐associated improvements in overall symptoms, quality of life, and corticosteroid use versus placebo were partially sustained at week 76. Conclusion Fifty‐two weeks of mepolizumab treatment is associated with sustained clinical benefits up to 24 weeks after discontinuation in patients with severe CRSwNP, which should be considered by physicians when making treatment decisions.