To conquer the inhibitory effects of immune checkpoints in human T cells, and protect normal cells from being disrupted by checkpoint inhibitors in a nonspecific manner, PD‐1 gene in T cells has been abolished by CRISPR/Cas9 to enhance the cytotoxicity against tumor target cells (Figure 2).39, 40 Hu et al reported that PD‐1 gene was eliminated in anti‐CD133 CAR‐T cells by nucleofection of CRISPR/Cas9 plasmids,41 producing enhanced cytotoxicity of CAR‐T cells and inhibition of tumor growth. Here, PDCD1 is linked to neoplasm.