Quantitative CT assessment of structural and functional response to omalizumab in severe allergic asthma: a prospective real-world study

While omalizumab has demonstrated clinical efficacy in severe allergic asthma, its impact on small airway function and structural changes remains underexplored. We aimed to evaluate the multidimensional effects of omalizumab using physiological, symptomatic, and quantitative CT (QCT) measures. This prospective observational study included 25 patients with severe allergic asthma treated with omalizumab for 16 weeks. Assessments included blood eosinophils, fractional exhaled nitric oxide (FeNO), spirometry, body plethysmography, Asthma Control Test (ACT), modified Medical Research Council (mMRC) dyspnea scale, 6-minute walk test (6MWT), inspiratory and expiratory quantitative computed tomography (QCT) scans. Changes before and after treatment were analyzed using paired Student’s t-tests, and Pearson’s correlation was used to explore inter-domain relationships. After 16 weeks of omalizumab treatment, patients showed significant reductions in airway inflammation, with Eosinophil counts showing a downward trend. FeNO decreasing from 69.3 ± 33.3 to 44.8 ± 23.8 ppb (p < 0.001). Maximal expiratory flow at 50% of forced vital capacity (MEF₅₀) increased from 1.89 ± 1.31 to 2.20 ± 1.19 L/s (p = 0.001), and maximal expiratory flow at 25% of forced vital capacity (MEF₂₅) increased from 0.61 ± 0.41 to 0.75 ± 0.52 L/s (p = 0.002). The residual volume/total lung capacity (RV/TLC) ratio decreased from 48.7 ± 10.2% to 41.7 ± 9.3% (p < 0.001). Asthma Control Test (ACT) scores improved from 17.4 ± 0.8 to 20.3 ± 1.2 (p < 0.001). Physical capacity increased, with 6MWT from 296.3 ± 54.5 to 327.9 ± 54.1 m (p < 0.001). QCT revealed a significant reduction in expiratory gas trapping volume from 382.4 ± 248.7 to 285.4 ± 176.1 mL (p = 0.004). Omalizumab was associated with short-term (16-week) improvements in type 2 inflammatory markers, pulmonary function, symptom control, and QCT-derived structural measures in patients with severe allergic asthma. QCT imaging showed reduced gas trapping over 16 weeks, suggesting that quantitative imaging may complement symptom-based assessment of biologic response. However, larger studies with longer follow-up are also needed to confirm the durability of these changes and their long-term clinical relevance.