Encephalitis Associated With Immune Checkpoint Inhibitor Treatment in Patients With Melanoma

Since the approval of immune checkpoint anti-programmed cell death protein 1 antibodies (pembrolizumab and nivolumab) and anti-cytotoxic T-lymphocyte-associated protein 4 (ipilimumab) in combination or monotherapy, significant advances have been made in the treatment of metastatic melanoma. The nonspecific immune stimulation resulting from these drugs can case a wide range of side effects in many organs including the nervous system, named immune-related adverse events. Few immune-related encephalitis associated with these antibodies have been described in the literature. It is a rare complication (<1% of the total of immune-related adverse events) but it can be fatal if not diagnosed and treated on time. We describe 3 cases of patients with melanoma, which were treated with a combination of ipilimumab-nivolumab (case 1), ipilimumab monotherapy (case 2), and nivolumab monotherapy (case 3), who developed an encephalitis which was related to immune checkpoint therapy.