CD4 and leukemia: Normal T cells with unregulated expression of PI-9, cathepsin B, and BCL-2 have also been shown to prevent cell death against engineered immune cells.126 They are also designed to attack CD4 antigens; CAR-T cells strongly destroy CD4 + leukemia cell lines in vitro lymphoma models and in vivo T cells.127 These findings suggest that engineered cells can provide appropriate therapeutic approaches but need many experiments.