Use of Immune Checkpoint Inhibitors in a Patient With Multiple Sclerosis and Metastatic Urothelial Cancer

Immune checkpoint inhibitors (ICIs) cross the blood–brain barrier and are effective treatments for brain metastases. However, patients with preexisting autoimmune diseases are excluded from ICI trials. We describe a case of a patient with a history of multiple sclerosis (MS) on interferon who developed urothelial cancer metastatic to the brain. He was treated with pembrolizumab for about 1 year without any immune-related adverse events or MS flares. This case suggests the safety of the administration of ICIs with immune-modulating treatment of MS in patients with limited treatment options for brain metastases.