Real-world sinonasal outcomes in patients with primary diffuse chronic rhinosinusitis treated with mepolizumab across polyp phenotypes

Mepolizumab effectively reduced systemic eosinophilia and radiographic disease burden in primary diffuse CRS, independent of phenotype or prior ESS. Symptom improvement was variable, highlighting the heterogeneity of clinical response. These findings support an endotype-driven approach to biologic therapy and suggest that IL-5 blockade may benefit selected CRSsNP patients.