Atezolizumab-induced myositis and myocarditis in a patient with metastatic urothelial carcinoma.

Immune checkpoint inhibitors have revolutionised cancer therapy in the past decade. Although they have been indicated to treat a diverse range of malignant neoplasms, they are also associated with various immune-related adverse effects. We report the case of a 74-year-old man with a history of urothelial carcinoma who had atezolizumab-induced myocarditis and myositis resulting in acute hypercapnic respiratory failure, despite the discontinuation of atezolizumab and aggressive treatment with corticosteroids. This case highlights the importance of a multidisciplinary approach for early diagnosis and treatment of immune-related adverse events. Physicians must be aware of the risks associated with immune checkpoint inhibitors and have a basic knowledge regarding their management.