Abstract 6872: Repurposing the DNA labeling agent EdU for glioblastoma treatment

Abstract Glioblastoma (GBM) is the most common and aggressive type of malignant central nervous system tumors, with over 300, 000 new cases diagnosed globally each year. Despite intensive efforts to improve survival with different treatment regimens, GBM is still deemed largely incurable. We previously found that 5-ethynyl-2’-deoxyuridine (EdU), which is commonly used in laboratories to study DNA replication, is recognized by mammalian cells as DNA damage, removed from the genome by nucleotide excision repair, and causes death of proliferating cells. Here, we evaluate the therapeutic potential of EdU for treatment of GBM, as EdU has been shown to cross the blood-brain barrier and incorporate into proliferating GBM cells but not into post-mitotic neurons. We tested the efficacy of EdU against several different model systems, including not only GBM cell lines in in vitro cell culture and in vivo orthotopic mouse models of GBM, but also living, uncultured GBM patient tumor tissues grown within our Organotypic Brain Slice Culture (OBSC) ex vivo platform. In all three model systems, EdU was effective in killing GBM cells. When compared to the standard of care drug Temozolomide (TMZ) in in vitro GBM cell survival assays, EdU displayed ED50 values orders of magnitude lower than TMZ in all five GBM tumor cell lines tested. Against two in vivo orthotopic brain tumor models, EdU significantly extended survival relative to controls. Using our OBSC ex vivo platform, we were able to quantify the capability of EdU to potently kill rapidly dividing cells within heterogeneous GBM patient tumor tissues without harming the healthy OBSC-associated brain tissue. EdU efficacy against a panel of patient GBMs largely correlated with the clinical Ki-67 status of each tumor, save for one tumor that remained unresponsive to treatment with both EdU and TMZ. Overall, these data suggest that (1) EdU has potential to be repurposed as an anticancer therapeutic and is especially adept at killing rapidly proliferating cells with low off-target toxicity; (2) the OBSC platform can measure nuanced differences in efficacy of experimental therapeutics on heterogeneous patient tumor tissues; and (3) OBSCs can continue to help identify potential responders and non-responders to EdU treatment via functional precision testing of patient tumors ex vivo. [HK and AA contributed equally to this work.] Citation Format: Humeyra Kaanoglu, Adebimpe Adefolaju, Casey Fraley, Mariah Shobande, Rajaneekar Dasari, Breanna Mann, Noah Bell, Stephen T. Keir, Shawn Hingtgen, Aziz Sancar, Andrew B. Satterlee. Repurposing the DNA labeling agent EdU for glioblastoma treatment [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 6872.