IMMU-12. Targeting a check point receptor of human primary natural killer cells via CRISPR/Cas9 potentiates anti-tumor activity in allogeneic glioblastoma

Abstract Although glioblastoma (GBM) immunotherapies have long been investigated, limited effective results have been reported. We developed an immunotherapy based on genome-edited natural killer cells (NKCs) with knocking out (KO) of checkpoint receptor T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), which would overcome the GBM immunosuppressive tumor microenvironment. The GBM TIGIT and TIGIT ligand expression patterns were analyzed with GlioVis and The Human Protein Atlas portal. We generated TIGIT KO human primary NKCs using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) with single guide RNA targeting different genome sites on TIGIT coding exons. The anti-GBM activity of the genome-edited NKCs was detected with a 2D adherent model and 3D spheroids derived from allogeneic GBM cells. We successfully obtained TIGIT KO NKCs and effective TIGIT expression KO with unchanged immune checkpoint receptor expression. T7 endonuclease I mutation detection assays demonstrated that the ribonucleoproteins disrupted the intended genome sites. Gene expression analysis demonstrated extremely minimal gene expression pattern changes, such as that for the immune responses, in the TIGIT KO NKCs. Targeting TIGIT KO using CRISPR/Cas9 enhanced NKC anti-tumor activity against the 2D adherent cells and 3D GBM spheroids. Immunotherapy based on CRISPR/Cas9-edited TIGIT KO NKCs could be a promising GBM therapy.