Abstract 1085: Exploiting bioenergetic vulnerabilities in chemotherapy resistant osteosarcoma

Abstract BACKGROUND: Osteosarcoma (OS) is the most common bone cancer in children and young adults. Standard treatment involves chemotherapy and surgical resection, yet nearly 4 in 10 patients experience disease relapse, and almost all of these patients are resistant to additional chemotherapy. Therefore, there is an urgent need to understand the biology of chemo-resistant OS and identify new therapeutic strategies to treat this therapy-resistant disease state. METHODS: Using a CRISPR-Cas9 based lineage tracing system, RNA sequencing, and Seahorse XF assays in chemo-naïve, -resistant, and -released human 143b and patient-derived 173x OS cell lines, we modeled the evolution of chemoresistance and release from the selective pressure of chemotherapy in osteosarcoma. The phenotype of each cell state was assessed through in vitro and ex vivo cell proliferation assays, a comparison of cell viability upon re-challenge to standard-of-care chemotherapy, and comparison of cell viability in response to novel therapies targeting alterations in cell respiration. RESULTS: Chemo-resistant OS cells demonstrate a decrease in expression of proliferation-associated gene pathways and shift their resources toward expression and maintenance of multi-drug resistance ABC transporters. Chemo-released cells maintain elevated expression of ABC transporters while re-activating proliferation. Across the spectrum of chemotherapy exposure, OS cells demonstrate changes in respiratory capacity, with unique bioenergetic phenotypes observed in chemo-naïve, -resistant, and -released cells. CONCLUSIONS: Chemo-resistant and chemo-released OS cells demonstrate unique bioenergetic patterns that correlate with gene expression signatures and growth phenotypes. Evolution imposed by the selective pressure of chemotherapy may render OS cells vulnerable to therapies that disrupt cellular energetics and exploit multi-drug resistant ABC transporters. Citation Format: Valerie U. Nguyen, Laurie Graves, Veronica Colmenares, Abol Macabangon, Casey Syal, Kelsey Fisher-Wellman, William C. Eward, So Young Kim, Jason A. Somarelli. Exploiting bioenergetic vulnerabilities in chemotherapy resistant osteosarcoma 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 1085.