Abstract 2944: A high-throughput screening system for identifying therapeutic targets in immuno-oncology

Abstract INTRODUCTION: Over the last decade, cancer immunotherapy has revolutionized cancer treatment. However, more than half of patients don’t respond, and responders often lack lasting effects. Understanding how genetic variants in cancer cells influence their interaction with immune cells, especially T cells, is crucial to uncover underlying mechanisms. Genetic screens are powerful for uncovering responsible genes for various phenotypes, but challenges in obtaining ample samples to set up a proper immune and cancer co-culture system have limited their use for identifying immune modulators in cancer: primary mouse T cells expressing CD3 against a specific antigen (typically albumin) need to be extracted from transgenic mice and only syngeneic mouse cancer cell lines that match these T cells can be paired, restricting the utilization of human T cells and human cancer cells for this co-culture screening setup. METHODS: Here, we present a highly scalable co-culture system that enables genome-wide CRISPR screens on a pair of human primary T cells and any allogeneic human cancer cell lines. This system utilizes the expression of a membrane-targeted protein in mammalian cells, named as ImBridge, which directly engages and activates CD3+ immune cells. This mechanism bypasses the need for matched MHC on target cancer cells. RESULTS: We validated activation of CD3+ immune cells and selective cancer cell cytotoxicity by ImBridge. A genome-scale CRISPR screen utilizing the co-culture system unveiled known immune-oncology targets including PD-L1 and PTPN2 and revealed MEDiC₀1 as a novel therapeutic target. Genetic loss of MEDiC₀1 in cancer cells significantly sensitized them to cytotoxic cells, effectively eliminating cancers in the presence of human PBMCs. CONCLUSION: We demonstrated a scalable and efficient approach for conducting high-throughput functional screens to uncover genes that modulate interactions between effector T cells and target cancer cells. This can facilitate the identification of new immuno-oncology therapeutic targets, insights into underlying mechanisms, and genetic factors influencing immune susceptibility and evasion. Citation Format: Dippal Parikh, Soon Youn Choi, Ki Eun Pyo, Hong-Pyo Lee, Kyuho Han. A high-throughput screening system for identifying therapeutic targets in immuno-oncology abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 2944.