Real‐World Effectiveness of Mepolizumab in Patients With Chronic Rhinosinusitis With Nasal Polyps: Findings From the European CRS Outcome Registry (CHRINOSOR)

Background The SYNAPSE phase 3 study demonstrated that mepolizumab significantly improves nasal polyp score (NPS), quality of life and symptom severity in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Objective We aimed to evaluate mepolizumab effectiveness in a real-world cohort from 12 tertiary centers in 6 European countries. Methodology A retrospective analysis was conducted in 110 CRSwNP patients (comorbid asthma: 86.4%). CRS-related outcomes were analyzed at baseline, 24 and 52 weeks of mepolizumab. Treatment response was evaluated based on EUFOREA 2021 criteria. Results Significant improvements in NPS, Sinonasal Outcome Test-22 (SNOT-22), and visual analog scale (VAS) symptom scores were observed at 24 and 52 weeks compared to baseline. Further improvement between weeks 24 and 52 was observed for NPS and SNOT-22. Asthma Control Test (ACT) also improved significantly by week 24 (ACT score ≥ 20: 64.5%). At least one response criterion (change in SNOT-22 ≥ 8.9, NPS ≥ 1, VAS total sinus symptoms ≥ 20, VAS nasal blockage ≥ 20, VAS loss of smell ≥ 20) was met by 85.6% and 78.7% of patients at 24 and 52 weeks, respectively. A more stringent composite response (SNOT-22 < 30, NPS < 4, VAS total sinus symptoms < 50, and VAS nasal blockage < 50) was achieved in 18.3% and 44.6% of patients at 24 and 52 weeks, respectively. Conclusion Mepolizumab demonstrated clinically meaningful benefits in a real-world CRSwNP population, with nearly half of patients achieving a beneficial composite treatment response by week 52. Notably, progressive improvements between weeks 24 and 52 underscore the value of prolonged therapy and the importance of evaluating treatment response at one year.