MBCL-18. ANALYSIS OF DNA METHYLATION PROFILES OF PEDIATRIC MEDULLOBLASTOMAS: EXPERIENCE AT THE BAMBINO GESÙ CHILDREN’S HOSPITAL

BACKGROUND: Medulloblastoma is the most frequent malignant brain tumor in children, still resulting fatal in about one third of affected patients. An accurate diagnosis is essential for correct therapeutic stratification. The DNA methylation profile (DMP) is a combination of changes in DNA methylation and genetic features that reflect the cell of tumor origin. DMP contributed to classify Medulloblastoma into four subgroups: WNT, SHH, Group 3/4 (the latter recently further subdivided into 8 subclasses). Each Methylation is associated with different genetic, demographic and clinical characteristics. We report our experience on Medulloblastoma molecular classification based on DMP. MATERIALS AND METHODS: 54 Medulloblastoma patients (28 males, 26 females) were selected. The DMP analysis was carried out via IlluminaEPICarrays. The results were obtained using the brain tumor classifier (Capper, 2018). RESULTS: In all cases the DMP allowed to classify the neoplasm, with an optimal score, in a defined methylation class. 10 WNTs, 15 SHHs, 10 Group 3, 19 Group 4 were found. Groups 3/4 were further refined based on the new consensus (Sharma 2019) in group I (n = 1); group II (n = 5); group III (n = 2); group IV (n = 4); group V (n = 3); group VI (n = 2); group VII (n = 6); group VIII (n = 7). CONCLUSIONS: This study carried out the first classification of Medulloblastomas diagnosed in Italy through DMP, demonstrating its high reproducibility, precision and accuracy. The molecular classification improves diagnostic accuracy and provides further information that can guide personalized treatment.