Genetic reprogramming for NK cell cancer immunotherapy with CRISPR/Cas9

Abstract

Natural killer cells are potent cytotoxic lymphocytes specialized in recognizing and eliminating transformed cells, and in orchestrating adaptive anti-tumour immunity. However, NK cells are usually functionally exhausted in the tumour microenvironment. Strategies such as checkpoint blockades are under investigation to overcome NK cell exhaustion in order to boost anti-tumour immunity. The discovery and development of the CRISPR/Cas9 technology offer a flexible and efficient gene-editing capability in modulating various pathways that mediate NK cell exhaustion, and in arming NK cells with novel chimeric antigen receptors to specifically target tumour cells. Despite the high efficiency in its gene-editing capability, difficulty in the delivery of the CRISPR/Cas9 system remains a major bottleneck for its therapeutic applications, particularly for NK cells. The current review discusses feasible approaches to deliver the CRISPR/Cas9 systems, as well as potential strategies in gene-editing for NK cell immunotherapy for cancers.

Keywords: NK dysfunction; checkpoint; delivery; genetic manipulation; off-target.

Figure 1

Schematic overview of the CRISPR/Cas9‐mediated genetic reprogramming of NK cells for cancer immunotherapy. Genetic editing of NK cells from various sources (PBNK: Peripheral Blood NK cells; UCB: Umbilical Cord Blood; hESCs: haematopoietic Embryonic Stem Cells; iPSCs: induced Pluripotent Stem Cells; NK‐92: NK‐92 cell line) via the CRISPR/Cas9 multiplexing by knocking out immune checkpoints and inhibitory signals, bolstering its tumour infiltration by integrating tissue homing receptors, improving its anti‐tumour activity by providing extra activating signalling, as well as enhancing its tumour specificity by arming with chimeric antigen receptors (CARs).