Anti-Programmed Death-Ligand 1 Antibody-Associated Eosinophilic Granulomatosis with Polyangiitis in Non-Small Cell Lung Cancer: A Case Report

Eosinophilic granulomatosis with polyangiitis (EGPA), a subtype of antineutrophil cytoplasmic antibody (ANCA)-related vasculitis, is rarely reported as an immune-related adverse event. We herein present the case of a 61-year-old woman with non-small cell lung cancer treated with durvalumab after definitive chemoradiotherapy. Following durvalumab treatment initiation, she experienced numbness in her hands and feet, and drop foot in her right ankle. She was subsequently diagnosed with peripheral neuropathy, eosinophilia, and myeloperoxidase-ANCA positivity, and had a history of asthma. Consequently, the patient was diagnosed as having EGPA. We report the first case of EGPA caused by durvalumab, an anti-programmed death-ligand 1 (PD-L1) antibody.