Heterogeneous response of airway eosinophilia to biologics in severe asthma patients

Abstract

<b>Introduction:</b> Severe eosinophilic asthma (SEA) is characterised by an increase in sputum and/or blood eosinophils and is clinically characterised with frequent exacerbations and oral glucocorticoid (OGK) treatment. The response to anti-IL-5 (anti interleukin 5) biologics is not&nbsp;equal in every patients and predictors of response to anti IL-5 biologics need further clarification. <b>Aims and objectives:</b> The aim of the present study was to find out whether there is a difference in peripheral blood and airway eosinophil counts in induced sputum of responders and non-responders to anti IL-5 biologics as early as 16 weeks after biologics introduction. <b>Methods:</b> We checked clinical parameters and peripheral blood eosinophil count at baseline and at 16 week of follow up in 17 adult patients with SEA who were followed for at least one year prior, and who were treated with anti IL-5 biologics (16 patients on mepolizumab and one patient on benralizumab). Sputum induction with eosinophil count was performed after 16 weeks in all patients. <b>Results:</b> There were 12 responders (R) and 5 non-responders (NR). For peripheral eosinophilia, we did not find any significant difference at baseline (p=0.749) between the R and NR. There was a statistically significant drop in all patients after 16 weeks (NR: p = 0.018; R: p = 0.0004) but there was no difference between groups (p = 0.689). NR had significantly higher concentrations of eosinophils in induced sputum (median 27%), compared to R (median 4.5%) after 16 weeks of treatment. <b>Conclusion:</b> In patients with SEA, airway but not peripheral blood eosinophilia might be a predictor of response and a complementary method to clinical assessment in response to biologics.