Abstract 1873: AST-05X: A novel GCN2 inhibitor as a promising anti-cancer approach for sarcoma

Abstract Background Integrated stress response (ISR) is an adaptive signaling pathway that responds to stress and plays an important role in cell fate determination. This pathway enables cellular adaptation and survival under stress conditions by activating specific genes that reduce protein synthesis. Tumors exist in a state characterized by heightened intrinsic and extrinsic stress, heavily relying on a balanced ISR to manage the metabolic demands for rapid growth. ISR (Integrated Stress Response) consists of four major kinases: GCN2, PERK, HRI, and PKR. GCN2 is activated by stress due to amino acid deprivation. Amino acids are crucial for cell survival, and cancer cells, require higher amounts than normal cells, particularly depending on conditionally essential amino acids like glutamine, asparagine, and arginine. GCN2 activation acts as a key mechanism for cancer cells to overcome amino acid deficiencies, making GCN2 a potential target, especially in conjunction with anticancer drugs like asparaginase. In this study, we aimed to identify a potential GCN2 inhibitor to explore a promising anti-cancer approach in sarcoma, a rare cancer with no new therapeutic alternatives. Method The activity verification of ISR kinases was characterized using in-vitro enzyme assays. In-vitro panel assays were employed to determine the selectivity profiling for oncology kinases. The modulation of the ISR pathway was validated using a sarcoma cell line (HT-1080) and a cell line derived from sarcoma patients. Western blot or ELISA assays were employed to measure phospho-GCN2, ATF4, phospho-eIF2a, and CHOP under both basal conditions and amino acid starvation conditions. Gene expression profiling (GEP) of sarcoma patient tissue samples (n=17) was conducted through RNA sequencing (RNAseq) analysis. Results AST-05X is a selective and potent GCN2 inhibitor. AST-05X inhibits the expression of GCN2 and ISR downstream factors (p-eIF2a, ATF, CHOP) in vitro cell-based experiments under amino acid deprivation. In addition, based on the results of ISR-related gene expression profiling GEP analysis, we identified potential CDx biomarkers for evaluating the diagnosis and treatment response of sarcoma. Conclusion This study is currently investigating the efficacy of the drug in sarcoma patient-derived xenograft models. AST-05X is a GCN2 inhibitor that has the potential to validate the inhibition of GCN2 as a promising anti-cancer approach for sarcoma, a rare cancer with limited therapeutic alternatives. Citation Format: Youngki Choi, Jinback Lim, Hyo-Hyun Park, Jinho Kang, Hyosong Kim, Kumhee Yun, Hun Jung. AST-05X: A novel GCN2 inhibitor as a promising anti-cancer approach for sarcoma 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 1873.