Ren et al. [79] also reported that triple knockout CD19 CAR T cells (TCRα/B2M/PD1) resulted in complete eradication of tumor cells in a leukemia murine model and further validated the clinical efficacy of CRISPR mediated triple knockout CAR T cells and this was consistent with the findings reported by Choi et al. [103]. The gene discussed is PDCD1; the disease is neoplasm.