LAUSR

Regulatory approval for the anti-programmed death 1 (PD-1) receptor monoclonal antibody (mAb) pembrolizumab represented a major therapeutic advance for patients with metastatic solid cancers [1]. As anticipated, immune checkpoint blockade of the PD-1/programmed death-ligand 1 (PD-L1) axis leads to unchecked immune responses and the development of autoimmune manifestations, referred to as immune-related adverse events (irAEs) [1]. Herein, we report a patient with metastatic urothelial carcinoma treated with pembrolizumab who developed fatal polymyositis (PM). The patient was a 83-year-old Chinese lady, recruited into a single-arm phase II trial of pembrolizumab at a fixed dose of 200 mg every 3 weeks, for metastatic urothelial carcinoma of the renal pelvis first diagnosed in 2006. In June 2015, she presented with haematuria and was noted to have enlargement of the left renal tumour with interval development of new pulmonary nodules. The patient did not have any preexisting