Continued administration of pembrolizumab for adenocarcinoma of the lung after the onset of fulminant type 1 diabetes mellitus as an immune-related adverse effect: A case report.

A 61-year-old woman with stage IVA lung adenocarcinoma exhibited high PD-L1 expression. Pembrolizumab was administered as second-line therapy. She developed destructive thyroiditis and her thyroid function started to decline during the administration of three to five courses. She was subsequently diagnosed with fulminant type 1 diabetes mellitus and ketoacidosis during the eighth course and insulin treatment was initiated. Pembrolizumab remained effective and was continued for 21 courses, even after the onset of diabetes mellitus. Immune-checkpoint inhibitor treatment can be continued with hormone replacement even after the development of type 1 diabetes mellitus as an immune-related adverse event.