PDCD1 and central nervous system cancer: While the PD-1 checkpoint inhibitor nivolumab recently failed to demonstrate a survival benefit in a first randomized clinical phase III trial (CheckMate 143, ClinicalTrials.gov Identifier: NCT02017717) in high-grade glioma, pembrolizumab appears to have a durable benefit for patients with recurrent PD-L1-positive glioblastomas (Omuro et al., 2017, Reardon et al., 2016).