Cerebral metastasis during remission after immunotherapy for metastatic urothelial carcinoma: A case report

Central nervous system (CNS) metastasis of urothelial carcinoma (UC) is rare. Immune checkpoint inhibitors, which were developed for the treatment of patients with advanced cancer, have limited efficacy against CNS metastases due to the unique immune microenvironment of the brain. The brain is an immune-privileged organ and is protected by the blood-brain barrier. However, the management of CNS metastases of UC is crucial to improving the prognosis. The present report describes two cases of cerebral metastasis occurring in the context of systemic disease control using immunotherapy. To the best of our knowledge, the present report is the first to describe a CNS metastasis during remission induced by immunotherapy.