Su et al. (2016, 2017) reported the knockout of PD-1 by electroporation of plasmids encoding CRISPR/Cas9 system was technically feasible and did not affect the viability of T cell in vitro. Besides, IFN-γ secretion and anti-tumor cytotoxicity of gene modified T cells was enhanced. A recently completed clinical trial have reported that PD-1 disrupted T cells by CRISPR/Cas9 were safe and feasible, but lack of efficacy in patients with non-small cell lung cancer (Lu et al., 2020). The gene discussed is PDCD1; the disease is neoplasm.