Abstract
BACKGROUND: Diffuse midline glioma (DMG) represents a highly aggressive pediatric brain tumour with no chance of survival. Treatment options are urgently needed, and efforts have been put towards the development of T cell immunotherapy. However, this should consider the unique tumour microenvironment (TME) of DMG, both in terms of anatomical location and developmental stage. MATERIAL AND METHODS: To gain knowledge on this unique tumour niche, we implemented an immuno-competent, syngeneic mouse model based on in-utero electroporation (IUE) of the key driver-mutations to induce tumour formation at embryonic stage. By combining snRNAseq, Spatial Transcriptomics and state-of-the-art imaging, we characterized the spatial and molecular landscape of DMG. RESULTS AND CONCLUSION: We observed a high intratumoral heterogeneity with spatially restricted cell populations. Importantly, their molecular profiles correlate with patient data, illustrating the clinical relevance of the IUE model. Analysis of cell-cell communications in the TME revealed a novel signalling between DMG and immunosuppressive myeloid cells, that could impact T-cell response. Using an advanced patient-derived DMG organoid co-culture model with macrophages and engineered T-cells, we are currently investigating the role of this pathway on T-cells mediated killing of DMG organoids. Thus, this project fills a critical need to delineate and overcome the immune-suppressive environment in DMG and potentiate T cell targeting.