Predictors of Early and Late Lung Function Improvement in Severe Eosinophilic Asthma on Type2-Biologics in the PRISM Study

Background: The determinants linked to the short- and long-term improvement in lung function in patients with severe eosinophilic asthma (SEA) on biological treatment (BioT) remain elusive. Objective: We sought to identify the predictors of early and late lung function improvement in patients with SEA after BioT. Methods: 140 adult patients with SEA who received mepolizumab, dupilumab, or reslizumab were followed up for 6 months to evaluate improvement in forced expiratory volume in one second (FEV₁). Logistic regression was used to determine the association between potential prognostic factors and improved lung function at 1 and 6 months of treatment. Results: More than a third of patients with SEA using BioT showed early and sustained improvements in FEV₁ after 1 month. A significant association was found between low baseline FEV₁ and high blood eosinophil count and sustained FEV₁ improvement after 1 month (0.54 [0.37–0.79] and 1.88 [1.28–2.97] odds ratios and 95% confidence interval, respectively). Meanwhile, among patients who did not experience FEV₁ improvement after 1 month, 39% exhibited improvement at 6 months follow-up. A high ACT score measured at this visit was the most reliable predictor of late response after 6 months of treatment (OR and 95% CI 1.75 [1.09–2.98]). Conclusion: Factors predicting the efficacy of biological agents that improve lung function in SEA vary according to the stage of response.