Possible Biological Heterogeneity of Airway Mucus Plugs in a Patient with Asthma

Background: The presence of mucus plugs in the airway is a severe phenotype in patients with asthma; however, the mechanisms and specific treatments are not fully understood.

Purpose: To clarify the efficacy of biologics and the mechanisms for mucus plug in patients with asthma.

Patients and methods: A 79-year-old Japanese asthmatic woman with high blood eosinophil and fractional exhaled nitric oxide (FeNO) was pointed massive mucus plugs in airway on chest CT imaging. She was treated with mepolizumab for 3 months; however, those were augmented without improvement of pulmonary function and FeNO. She was switched to dupilumab and, three months later, the mucus plugs were completely disappeared with improvement in pulmonary function, FeNO and asthma-related symptoms. She continues treatment with dupilumab, and her asthma symptoms are stable.

Conclusion: Biologics including mepolizumab and dupilumab have been reported to improve mucus plugs in patients with asthma; however, their efficacy might be different depending on the clinical characteristics of patients. Present data remind us of the possibility that, if FeNO levels remain high after treatment with anti-IL-5 antibody in asthma patients with mucus plugs, switching to other biologics, including anti-IL-4Rα antibody, might be considered.