Mucus Plug Score predicts clinical and pulmonary function response to biologic therapy in patients with severe Asthma.

Background: Mucus plugging has been identified as an important feature of severe asthma contributing to airway obstruction and disease severity. Recently, improvement of mucus plugging has been found upon treatment with several biologic therapies.

Objective: We aimed to analyze associations of baseline characteristic with mucus plugging score (MPS) and asked whether MPS at baseline predicts the clinical and functional response to biologic treatment in patients with severe asthma.

Methods: We retrospectively analyzed biologic-naïve patients with a suitable CT scan available at baseline. We calculated the MPS and analyzed correlations with baseline parameters and improvements of biomarkers, pulmonary function and clinical parameters after 4 months of biologic therapy.

Results: We included n=113 patients in the baseline cohort, hereof n=101 patients with sufficient data after 4-months of biologic therapy for the follow-up analysis. CT showed mucus plugging in 77% of patients with a median MPS of 4. Multivariate regression analysis showed correlation of MPS with lower FEV1 (rho= -0.24, p=0.009) and DLCO (rho=-0.26 , p= 0.01), and higher FeNO (rho=0.36 p=0.0003) at baseline. Patients received treatment with anti-IgE (8.8%), anti-IL5 (27.4%), anti-IL5R (37.2%), anti-IL4R (25.7%) and anti-TSLP (0,9%) in clinical routine. Baseline MPS correlated with improvements of FEV1 (beta=0.72; p=0.01) and ACT (beta= 0.24; p= 0.001) in multivariate regression analysis.

Conclusion: Our study suggests that higher MPS correlates with worse pulmonary function at baseline, but also predicts a larger clinical and pulmonary function response to biologic therapies in severe asthma.