PDCD1 and glioblastoma: Furthermore, engineered CAR-T cells expressing immune checkpoint antibodies (e.g., CAR-T cells expressing anti-PD-1 and anti-CTLA-4 mAbs) may represent a new direction for GBM treatment, and several clinical trials (e.g., NCT02873390, NCT02937844, and NCT03182816) are ongoing.