CTLA4 and melanoma: Ipilimumab is a fully human monoclonal antibody targeting the Cytotoxic T-lymphocyte antigen-4 (CTLA-4) inhibitory immune checkpoint.22 Systemic CTLA-4 blockade prolongs survival in preclinical glioblastoma models.23,24 Efficacy in brain metastases in patients with melanoma provides clinical evidence within the central nervous system.25,26