BACKGROUND. T2 inflammation underlies non-allergic eosinophilic severe bronchial asthma and chronic rhinosinusitis with nasal polyposis (CRSwNP). Existing targeted anti-IL-5 drugs can improve clinical and functional parameters in patients with a combination of severe asthma and CRSwNP.
 AIM: to evaluate mepolizumab efficacy in patients with non-allergic severe asthma and concomitant inflammatory nasal diseases (CIND) in real clinical practice.
 MATERIALS AND METHODS. The study was conducted without a control group, by comparing related populations (before-after analysis) and based on the Sverdlovsk regional register of adult patients with severe asthma and CIND. The primary endpoint was asthma control achievement (ACT questionnaire) and decrease in the proportion of patients with uncontrolled severe asthma. The number of asthma exacerbations, emergency calls and hospitalizations, quality of life according to AQLQ questionnaire, peripheral blood eosinophils level and respiratory function (FEV1, FVC, FEV1/FVC) were also assessed. Dynamics of nasal symptoms was assessed using SNOT22 questionnaire and visual analogue scale (VAS).
 RESULTS. During 12 months of therapy with mepolizumab, ACT increased from 9 (Q1-Q3: 7-11) to 22 points (Q1-Q3: 21-24) (p0.001). The proportion of patients with uncontrolled asthma decreased from 100% to 10% (p0.001). The number of asthma exacerbations decreased from 3.182.8 per patient per year to 0 (p0.001) and hospitalizations from 0.570.9 per patient per year to 0 (p=0.007). Quality of life according to AQLQ increased from 3.481.05 (95% CI 2.734.24) to 5.590.88 (95% CI 4.966.22) points (p0.001). The number of blood eosinophils decreased from 442 (Q1-Q3: 336-853) to 90 (Q1-Q3: 73-117) cells/l (p0.001). There was increase in FEV1 from 63.9%24.2 (95% CI 46.681.2) to 80.5%18.3 (95% CI 67.493.6) (p=0.015). There was decrease in SNOT22 questionnaire score by 33 points (from 4530 to 2215) (p=0.006) and decrease in VAS score by 5 points (from 8 (Q1-Q3: 5-8) to 3 (Q1-Q3: 3-5)) (p=0.017).
 CONCLUSIONS. According to the study results, there were asthma control improvement, asthma exacerbations decrease, quality of life improvement according to AQLQ. Statistically significant peripheral blood eosinophils decrease and respiratory function improvement were also revealed. In patients with CIND, significant improvement in nasal breathing was noted, which was confirmed by scores of SNOT22 and VAS questionnaires.