Cytotoxicity of CD19-CAR-NK92 cells is primarily mediated via perforin/granzyme pathway

Chimeric antigen receptors (CARs) have improved cancer immunotherapy in recent years. Immune cells, such as Natural killer cells (NK-cells) or T cells, are used as effector cells in CAR-therapy. NK92-cells, a cell line with known cytotoxic activity, are of particular interest in CAR-therapy since culturing conditions are simple and anti-tumor efficacy combined with a manageable safety profile was proven in clinical trials. The major pathways of immune effector cells, including NK92-cells, to mediate cytotoxicity, are the perforin/granzyme and the death-receptor pathway. Detailed knowledge of CAR-effector cells' cytotoxic mechanisms is essential to unravel resistance mechanisms, which potentially arise by resistance against apoptosis-inducing signaling. Since mutations in apoptosis pathways are frequent in lymphoma, the impact on CAR-mediated cytotoxicity is of clinical interest. In this study, knockout models of CD19-CAR-NK92 cells were designed, to investigate cytotoxic pathways in vitro. Knockout of perforin 1 (Prf1) and subsequent abrogation of the perforin/granzyme pathway dramatically reduced the cytotoxicity of CD19-CAR-NK92 cells. In contrast, knockout of FasL and inhibition of TRAIL (tumor necrosis factor-related apoptosis-inducing ligands) did not impair cytotoxicity in most conditions. In conclusion, these results indicate the perforin/granzyme pathway as the major pathway to mediate cytotoxicity in CD19-CAR-NK92 cells.

Automated summary

Chimeric antigen receptors (CARs) have been effective in improving cancer immunotherapy, especially using immune cells like NK cells or T cells as effector cells. NK92 cells, a cell line with known cytotoxic activity, are particularly promising in CAR therapy due to their simplicity in culturing conditions and proven anti-tumor efficacy with a manageable safety profile. Understanding the cytotoxic mechanisms of CAR effector cells is crucial in uncovering potential resistance mechanisms, especially in lymphoma cases with frequent apoptosis pathway mutations. This study found that the perforin/granzyme pathway is the major pathway mediating cytotoxicity in CD19-CAR-NK92 cells, as knockout of perforin 1 significantly reduced their cytotoxicity.