MODL-09. Zebrafish—A Suitable Model for Rapid Discovery of Effective Pediatric Cancer Therapeutics

Abstract Pediatric brain cancers have the highest mortality rate among childhood cancers, with high-grade gliomas being particularly challenging to treat due to the blood-brain barrier and systemic toxicity. PDX rodent models require approximately six months to develop, limiting their utility for drug testing, given the median survival of 8–11 months for DIPG patients. This study highlights the advantages of zebrafish for drug toxicity assessment, pediatric brain cancer model development, and drug screening. We assessed toxicity of eight clinically relevant drugs with diverse mechanisms of action. In addition to the survival assay (LC50), we analyzed teratogenic characteristics to demonstrate the detrimental developmental toxicity, which was critical in determining drug safety for future human usage.To develop rapid and reproducible orthotopically xenografted pediatric brain cancer models, we injected approximately 80-100 mCherry expressing JHH-NF1-PA1, Res186 and TM-31 cells into the midbrain of 2 days post-fertilization zebrafish embryos and imaged daily for next 4 days to monitor the survival, progression, and invasion of the injected cells. We found that all the cell types engrafted successfully and multiplied within the developing zebrafish brain. As compared to JHH-NF1-PA1 cells, which mostly migrated caudally within the developing spinal cord, TM-31 cells migrated in multiple directions and metastasized five times more rapidly as compared to JHH-NF1-PA1 and Res186 cells. To test the efficacy of VAL-083 and AZD-1775 in high-grade gliomas, zebrafish embryos injected with mCherry-expressing SF8628 cells were treated with these drugs individually and in combination. After 72 hours, tumor invasion and migration were analyzed. The combination therapy significantly reduced tumor burden, as indicated by lower fluorescence intensity, reduced migration area, and fewer metastatic cells (p 0.001) compared to single or no treatment. Our findings demonstrate zebrafish as a valuable, rapid, and cost-effective in vivo model for studying pediatric brain cancer, tumor metastasis, and drug screening.