Development of myasthenia gravis: 4 years after durvalumab‐induced myositis

We report a 74‐year‐old man diagnosed with myasthenia gravis (MG) accompanied by anti‐acetylcholine receptor antibody seroconversion and positive for anti‐titin antibody, with onset delayed by 4 years after the final durvalumab administration, which preceded myositis and organizing pneumonia (OP). Durvalumab, an anti‐programmed cell death ligand 1 antibody, is effective in patients with cancer and causes immune‐related adverse events (irAEs) retrospectively. Patients treated with immune checkpoint inhibitors require vigilant monitoring as irAEs can arise at any phase, regardless of the time after immune checkpoint inhibitor discontinuation.