In the current and future studies of engineered cell therapy, such as CAR-T-cell or TCR-T-cell therapy, the knockout of one or more genes to increase the infiltration of CD8+ T cells in the TME, the killing effect on the tumour, and the persistence of immune cells are very useful tools and strategies (Mai et al, 2023; Prinzing et al, 2021; Wei et al, 2019). This evidence concerns the gene CD8A and neoplasm.