DUAL COMBINATION DRUG TREATMENT FOR GROUP 3 MEDULLOBLASTOMA

Abstract AIMS Group 3 medulloblastoma (MB) confers a 5-year survival of less than 45% in infants of <3 years and 58% in children. Radiotherapy poses significant risk to young patients and is avoided in infants. Therefore, better treatment modalities are required to increase survival and quality-of-life of these patients. The aim of this work was to identify a drug combination for group 3 MB based on RNAseq data generated from 3D cell culture to trial in vivo. METHODS To mimic the post-surgical microenvironment for group 3 MB, human astrocytes and group 3 MB cells were co- cultured in a 3D human brain-hydrogel matrix. After 7 days, cells were sorted via FACS, and RNAseq identified differentially expressed genes (DEGs) when compared to 3D monocultures. These DEGs informed a targeted drug screen analysing potency and anti-migratory effects. Promising combinations are now being tested in vivo. RESULTS Three group 3 MB cell lines (d283, d341, d425) were cultured in the 3D model and characterised. RNAseq re- vealed upregulation of “S100A10,” “SERPINE1,” “COL1A1,” and “SOCS3” in the presence of astrocytes across all 3 cell lines. Ingenuity pathway analysis identified mTOR and other upstream regulators as further potential targets, with pathway enrichment suggesting astrocytes promote proliferative and migratory MB phenotypes. Based on this, 21 drugs were screened for potency, with halofuginone, AZD8055, juglone, and BB-Cl-amidine showing high sensitivity. Thirteen drug combinations (cytotoxic with a potentially anti-migratory drug) were tested using BLISS and ZIP synergy models, with four additive combinations advancing to migration assays. AZD8055 and T-5224 were found to significantly reduce migration in d425 spheroids. CONCLUSION A combination drug approach may improve group 3 MB outcomes by enhancing survival and reducing radio- therapy risks. AZD8055 and T-5224 impaired MB cell viability and migration and are now being tested in vivo. The pro-tumorigenic influence of astrocytes on group 3 MB also warrants further study.