PDCD1 and brain neoplasm: Our data indicate that combining D2C7-IT with antibodies that block the immune checkpoints PD-1 (to reactivate exhausted tumor-specific T cells) and CTLA-4 (to inhibit immunosuppressive Tregs), or PD-L1 (to block PD1/PDL1 pathway) may reinstate immunosurveillance in brain tumors.