1124 Discovering transcriptional regulators of T cell exhaustion for epigenetic reversal of T cell dysfunction

• DOI: 10.1136/jitc-2024-sitc2024.1124
• Publication Date: 2024-11-05T14:58:49Z
• Authors: Christian D McRob...; Rachel E Savage; Aretha R Gao; Sean R McCutcheon; Jason D Buenrostro; Charles A Gersbach

<h3>Background</h3> T cells are part of the immune system's adaptive defence; they specifically target and kill both virally infected cancerous through antigen recognition. Unfortunately, cancer can exploit intrinsic cell mechanisms to survive attack by system. exhaustion arises from chronic stimulation, which shifts a portion population exhausted state (T_EX), resulting in diminished proliferation tumor/viral clearance. Modern genome engineering technologies have potential dramatically advance therapy programming T_EX into desirable phenotypic states. The transcription factor (TF) TOX drives maintains epigenetic regulation exhaustion-associated programs. <h3>Methods</h3> To recapitulate vitro, we repeatedly stimulated primary human with anti-CD3/CD28 beads mimic stimulation confirmed induction program via RNA- ATAC-seq. understand what other TF regulators might be driving or preventing upstream TOX, designed screens using an Open Reading Frame (ORF) library encoding all TFs protein expression as readout. CD8+ three distinct donors were used acute setting (one TCR stimulation) (two additional stimulations). Comparing screen results context versus facilitated identification factors specific state. <h3>Results</h3> Over 100 ORFs enriched TOX-high TOX-low bins, including known novel TOX. comprehensively look at transcriptomic, epigenomic, functional effects top had on acutely chronically cells, sub pooled screened final Phorbol myristate acetate ionomycin (PMA/IO) Simultaneous High-throughput ATAC RNA sequencing (SHARE-seq) Computational analysis revealed THAP6 improving response pushing away chromatin Individual validation downregulation multiple markers FACS improved bead-based cytokine assay. <h3>Conclusions</h3> Ongoing work is focused validating function (T killing assays), transcriptome (bulk RNA-seq), epigenome ATAC-seq). Through reprogramming, hope achieve clinically relevant phenotypes improve current immunotherapies viral infection contexts.