Sputum Type 2 Markers Could Predict Remission in Severe Asthma Treated With Anti-IL-5

Abstract

Background: Biotherapies targeting IL-5 allow a tangible improvement of asthma. However, all patients do not respond the same way to these treatments. Even if high blood eosinophil counts seem to be associated with a reduction in exacerbations with treatment targeting IL-5, we lack biomarkers for the prediction of remission after these very expensive treatments.

Research question: Are there biomarkers of remission after therapy targeting IL-5 in the sputum of patients with severe eosinophilic asthma?

Study design and methods: This observational study included 52 patients with severe asthma initiated with anti-IL-5 therapy and recruited from the asthma clinic of the Centre Hospitalier Universitaire of Liege, Belgium. Remission was defined as patients who combined the following at 1 year after therapy: no chronic treatment with oral corticosteroids; no exacerbation; asthma control questionnaire score < 1.5, asthma control test score > 19, or both; FEV₁ of ≥ 80% predicted, improvement of FEV₁ of ≥ 10%, or both; and a blood eosinophil count < 300 cells/μL. Eosinophil peroxidase (EPX), IgE, IL-3, IL-4, IL-5, IL-13, IL-25, IL-33, granulocyte-macrophage colony-stimulating factor, thymic stromal lymphopoietin (TSLP), and eotaxin-1 levels were measured in the sputum of these patients before anti-IL-5 treatment.

Results: Among the 52 patients, 11 were classified as being in remission. These patients were characterized by higher sputum eosinophil, macrophage, and lymphocyte counts, whereas the sputum neutrophil percentage was lower than in the nonremission group. In addition, the sputum eotaxin-1, TSLP, IL-5, EPX, and IgE protein levels were higher at baseline in the remission group compared with the nonremission group. Univariate regression analysis revealed that male vs female sex, sputum neutrophil percentage, eotaxin-1, IL-5, and EPX were potential predictors of remission.

Interpretation: Sputum type 2 markers seemed to be potentially predictive of remission after anti-IL-5 therapy in a cohort of patients with severe eosinophilic asthma. These results need validation on a larger cohort.

Keywords: asthma; biotherapy; remission; sputum.