HGG-03. THE GLYCOSPHINGOLIPIDS METABOLISM IS A NOVEL TARGET IN H3K27M-MUTANT DIFFUSE MIDLINE GLIOMA

Abstract

H3K27M-mutant diffuse midline glioma (H3K27M-mutant DMG) is a rare malignant brain tumour entity in children and adults with a median overall survival of around 12 months. Genomic and proteomic analysis may help to identify new target structures, however not all relevant targets are covered by these analyses. Glycosphingolipids and particularly gangliosides play a major role in brain development and have been involved in the pathology of brain tumours. The conversion of ceramide to glucosylceramide via glucosylceramide synthase (GCS) is one of the first steps in the synthesis of glycosphingolipids. Therefore, targeting GCS will inhibit their synthesis. Here we analysed the glycosphingolipids composition and tested GCS inhibitors in an in vitro model of H3K27M-mutant DMG. Methods: H3K27M-mutant DMG primary cells were established from needle biopsies of two paediatric patients and characterised by immunohistochemistry. Glycosphingolipids were analysed by thin layer chromatography, liquid chromatography-coupled tandem mass spectrometry and flow cytometry. The effect of the GCS inhibitor eliglustat on the cell proliferation was examined. Results. The primary cells maintained the features of the tumour of origin, including the H3K27M mutation. Neutral glycosphingolipids with 1 to 4 monosaccharides and the ganglioside GD2 were expressed at high concentration. Eliglustat completely abrogated the proliferation of the H3K27M-mutant DMG primary cells. Conclusions. The glycosphingolipids oncometabolism represents a novel target in H3K27M-mutant DMG. The GCS inhibitors eliglusat and miglustat are already used to treat paediatric patients with the lysosomal storage disorders Niemann Pick’s and Gaucher′s disease and miglustat can cross the blood-brain barrier. Thus, our finding may accelerate the access of H3K27M-mutant DMG patients to novel innovative clinical studies based on the inhibition of the glycosphingolipids metabolism.