PDCD1 and neoplasm: Several recent clinical trials have demonstrated the safety and efficacy of combining ATC with CTLA-4 and PD-1/PDL1 targeting strategies: for example, using anti-PD-1 as an immune booster after intrapleural CAR T-cell administration in patients with mesothelin-positive malignant pleural disease (18), novel third-generation CAR T-cells with the capability for expressing and secreting CTLA-4 and PD-1 antibodies into the tumor microenvironment (19), and CRISPR/Cas9 PD-1 knockout CAR T-cells (20).