The immune checkpoint PD-1/PD-L1 axis may also be implicated in GBM-related immunosuppression.71 CRISPR/Cas9 gene editing to target PD-1 in EGFRvIII-CAR-T cells improved cancer growth inhibition in vitro and in vivo.72,73 Intracranial injection of EGFRvIII-CAR-T cells with deleted PD-1 led to significantly improved survival, which further suggests a role for the PD-1/PD-L1 axis. This evidence concerns the gene PDCD1 and glioblastoma.