Abstract
Pembrolizumab is an anti-programmed cell death-1 (PD-1) antibody used to treat various cancer types. Treatments with such immune checkpoint inhibitors cause immune-related adverse events. However, airway inflammation caused by immune-related adverse events has rarely been reported. A 54-year-old woman with endometrial cancer experienced asthma exacerbation, and increased blood eosinophil counts 3 months after pembrolizumab administration. Although asthma exacerbation improved, the resumption of pembrolizumab caused the recurrence of dry cough and hypereosinophilia. The discontinuation of pembrolizumab improved her symptoms. Serum interleukin-5 levels increased during pembrolizumab treatment but decreased upon discontinuation. The blockade of PD-1 and its ligand may exacerbate asthma through eosinophilic inflammation.