Abstract B007: The organotypic brain slice culture platform as a functional biomarker for preclinical drug performance testing
Authors: Adebimpe Adefolaju, Humeyra Kaanoglu, Breanna Mann, Xiaopei Zhang, Noah Bell, Morrent Thang, Rajaneekar Dasari, Nichole Artz, Andrew Buckley, Lee Graves, Shawn Hingtgen, Aziz Sancar, Andrew Satterlee
Journal: Cancer Research (2025)

Abstract Of the roughly 1% of brain cancer therapeutics that show promise in preclinical testing, about 85% fail in clinical trials, indicating that drugs should be further scrutinized in preclinical settings. This failure is partially attributed to the inability of many preclinical models to recapitulate relevant aspects of disease and response to treatment, thereby misrepresenting a drug's therapeutic potential. Hence, we developed an Organotypic Brain Slice Culture (OBSC)-based platform that allows the direct testing of drugs on cell lines and living, uncultured patient brain tumor tissues to obtain functional readouts that capture both anti-tumor efficacy and off-target toxicity in a summarized drug sensitivity score (DSS). In this rapid, four-day assay, cells or tumor tissues are seeded atop coronal sections of postnatal day 8 rat pup brains just after slicing, therapeutics are added the next day, and live tumor bioluminescence is quantified three days after treatment initiation. In a parallel assay, off-target toxicity to non-tumor-bearing OBSCs after treatment is assessed using a propidium iodide assay that quantifies OBSC-associated cell death. Here, we investigated the antitumor activity of two experimental compounds, TR-107, a potent ONC201 derivative, and EdU, a newly repurposed DNA labeling agent, against an array of cell lines and brain tumor tissues. We then compared tumor survival on OBSCs to the standard of care and/or other relevant drugs tested in our system. The potency and selectivity of TR-107 in our assay is unsurprising as its parent compound, ONC 201, is the first imipridone in Phase 3 trials for treating H3- K27M gliomas. When investigating EdU against patient tumor tissues on OBSCs, we observed that intertumoral differences in Ki-67 abundance, a proliferation marker measured by clinical pathology, correlated with the effective doses necessary to eliminate up to 50% of these heterogeneous tumors. Importantly, while many of our results correlate with expected outcomes, we also identified non-responding tumor tissues whose “static” biomarkers predicted otherwise, reinforcing the need for functional approaches to drug development. In summary, this data supports the use of our OBSC platform as a functional biomarker for drug performance against cell lines and heterogeneous patient tumor tissues, and as an assay that can provide insight into discordance between genomic predictions and functional outcomes long before a drug fails in the clinic. Citation Format: Adebimpe Adefolaju, Humeyra Kaanoglu, Breanna Mann, Xiaopei Zhang, Noah Bell, Morrent Thang, Rajaneekar Dasari, Nichole Artz, Andrew Buckley, Lee Graves, Shawn Hingtgen, Aziz Sancar, Andrew Satterlee. The organotypic brain slice culture platform as a functional biomarker for preclinical drug performance testing [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Functional and Genomic Precision Medicine in Cancer: Different Perspectives, Common Goals; 2025 Mar 11-13; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(5 Suppl):Abstract nr B007.