PDCD1 and glioblastoma: We selected nivolumab instead of atezolizumab, since this seemed to be the strongest contestant in comparison to the XVir-N-31-anti-PD-L1 expressed anti-PD-L1 as PD-1 expressed on lymphocytes should already be capped by nivolumab outside the brain, thus avoiding the exhaustion of TILs by GBM expressed PD-L1 during the infiltration phase.