A Case of Fatal Immune Checkpoint Inhibitor-related Pancreatitis.

We herein report a case of fatal pancreatitis induced by an immune checkpoint inhibitor. A 62-year-old man with cancer of unknown primary was treated with pembrolizumab. After 12 cycles, immune-related pneumonitis developed and was treated with prednisolone. Three months later, pancreatitis developed, which was successfully treated with hydration and protease inhibitors. Eight months later, another attack of pancreatitis occurred, which did not respond to therapy, including high-dose corticosteroids, and he eventually died. This is the first report describing fatal immune checkpoint inhibitor-related pancreatitis. Despite the rarity of this complication, attention should be paid to its potential severity and treatment.