Asthma caused by durvalumab after chemoradiotherapy in two patients with non‐small cell lung cancer

Durvalumab, an anti‐programmed cell death‐ligand 1 (PD‐L1) antibody, is currently used in the maintenance therapy for patients with stage III non‐small cell lung cancer after platinum‐based chemoradiotherapy. A 69‐year‐old male with lung adenocarcinoma, clinical stage IIIA, was treated with chemoradiotherapy. As the treatments progressed, his dry cough gradually subsided. After chemoradiotherapy had been completed, we started durvalumab administration. One month later, his dry cough relapsed and persisted. Based on the changes of his blood eosinophil counts, we clinically diagnosed him with asthma. A 71‐year‐old male with lung adenocarcinoma, clinical stage IIIB, was treated with chemoradiotherapy. After completing chemoradiotherapy, we initiated durvalumab administration. After 6 months, his dry cough was noticed to involve wheezing. Based on his spirometric values and the fraction of exhaled nitric oxide, a clinical diagnosis of asthma was established. Asthma should be considered as one of the possible side effects when immune checkpoint inhibitors are used in cancer treatment.