Abstract 227: In vivo functional genomics screen to uncover tumor intrinsic negative regulators of NK cell-mediated tumor cell killing

Abstract

Abstract Natural killer cells are innate immune cells whose activity is gated by activating and inhibitory receptors that bind ligands on potential target cells. NK cell gene signatures are associated with improved survival in several indications, and NK cell therapies have shown some encouraging results in the clinic. These data highlight the relevance of this cell type in anti-tumor immunity and has given rise to interest in amplifying NK responses to cancer as a complementary therapeutic strategy to current T cell based immunotherapies. The goal of this project is to identify tumor cell intrinsic negative regulators of NK cell-mediated tumor cell killing through in vivo CRISPR/Cas9 screening, with identification of both PD-1 blockade-dependent and -independent regulators. The syngeneic B16F10 model in C57Bl6 mice was used with or without NK depletion and with or without anti-PD1 treatment, with a custom library of 900 genes split into four subpools (one guide per gene per subpool). B16F10 cells were transduced in vitro and inoculated into mice ten days after spinfection. On day 14 after inoculation, tumors were harvested and subsequently the gDNA was isolated and sequenced. QC analysis indicated good guide recovery and screen performance. There were several hits from this screen that were depleted in the NK+ context but not in the NK depleted context, indicating their potential role in regulating NK mediated cell killing. Of the hits, several expected genes scored including B2M which is a known negative regulator of NK cell killing. Validation efforts include confirmation of dropout in other models as well as in vitro co-culture assays to assess enhanced NK killing of single gene KO cells. The hits identified in the screen will increase our understanding of anti-tumor immunity and serve as potential novel Oncology targets. Citation Format: Kayla Duval, Elsa Krall, Federica Piccioni, Maria Monberg, Marianne Spatz, Tobias Ehrenberger, Nicole Follmer. In vivo functional genomics screen to uncover tumor intrinsic negative regulators of NK cell-mediated tumor cell killing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 227.