Eosinophilic reactive airways disease after immune checkpoint inhibitor treatment

Immune checkpoint inhibitors (ICI) are increasingly utilized as first-line treatment for many solid tumour malignancies. One downside of ICI therapy is autoimmune-mediated organ inflammation, or immune-related adverse events (irAE). ICI-related pneumonitis, or non-infectious inflammation of the lung, is a well-described irAE. While guidelines surrounding ICI-related pneumonitis are well established, other ICI-related pulmonary toxicities, including reactive airways disease, are rarely described in the literature. Here, we present a series of patients without pre-existing COPD or asthma who developed reactive airways disease with peripheral eosinophilia after ICI therapy and without radiographic evidence of pneumonitis. The patients were treated with typical therapies for reactive airways disease, including- inhaled steroids, bronchodilators, systemic steroids, and in one instance, dupilumab. All experienced symptomatic improvement with these therapies, enabling some of the patients to continue receiving ICI therapy.