Abstract 5376: Unraveling the metabolic Achilles' heel of pancreatic ductal adenocarcinoma: targeting ref-1 and beyond

Background & Objective: Treating pancreatic ductal adenocarcinoma (PDAC) remains exceptionally difficult, with scant advancements in clinical management over the last thirty years. Aptly dubbed the "graveyard of chemotherapy," PDAC poses formidable clinical challenges. Even the most effective first-line chemotherapy regimens merely extend median survival for patients with metastatic disease beyond 12 months. Due to its poorly vascularized and fibrotic environment, tumor cells encounter hypoxia and nutrient scarcity and hence adapt metabolically by engaging processes like autophagy and macropinocytosis. Key genes such as HIF1A, KRAS, and MYC help PDAC reshape tumor metabolism favoring glycolysis thereby, promoting metastasis and therapy resistance. Targeting these cancer-specific metabolic genes offers a promising approach to overcoming PDAC's inherent and acquired chemoresistance. Redox effector factor-1 (Ref-1) activates various transcription factors through its redox activity, including HIF-1α, contributing significantly to metabolic reprogramming and altered gene expression in PDAC. We recently published Ref-1’s redox function as crucial for mitochondrial metabolic regulation, and that inhibition of Ref-1 suppresses the TCA cycle, Oxidative phosphorylation (OXPHOS), and tumor growth and metastasis in PDAC models. As further proof of Ref-1’s role in regulating OXPHOS, PDAC cells are more sensitive to Ref-1 inhibitors in galactose-containing media than glucose. Therefore, we hypothesize that Ref-1 inhibitor efficacy can be increased by identifying additional tumor-specific metabolic targets that induce synthetic lethality when combined with Ref-1 inhibition. Methods: Two approaches were used to identify Ref-1 synergistic metabolic targets: global metabolomics profiling (Pa03C) and a metabolism-centered CRISPR/Cas9 KO library screening (MiaPaCa2) after treatment with APX2014, a potent Ref-1 redox inhibitor. Results & Conclusion: The CRISPR screen identified several interesting synthetic lethal genes for combination with Ref-1 redox inhibition, including PRDX1, G6PD, and SEPHS2. Further, integration of the global metabolomics profile with our published scRNA seq data shows significant changes in both substrates and enzyme gene expression of multiple metabolic pathways, with a predicted decrease in TCA cycle and nucleotide biosynthesis, and increased glutaminolysis following Ref-1 inhibition. Ongoing studies include the prediction of combinatorial lethality enabled by co-suppression of Ref-1 and other metabolic targets and validation using our in vitro and in vivo model of PDAC PDX tumor lines co-cultured with matched cancer-associated fibroblasts. Citation Format: Silpa Gampala, Jacqueline Peil, Sanya Hayati, Sonia Kiran, Caleb Cheng, Elizabeth A. Potchanant, Costas Lyssiotis, Chi Zhang, Sha Cao, Mark R. Kelley, Melissa L. Fishel. Unraveling the metabolic Achilles' heel of pancreatic ductal adenocarcinoma: targeting ref-1 and beyond [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5376.