PD-L1/miR-155 Interplay in Pediatric High-Grade Glioma.

High-grade pediatric glioma (p-HGG-WHO 2021, formerly GBM-WHO 2016), as a common, aggressive, and highly lethal primary brain malignancy in adults, accounts for only 3-15% of primary brain tumors in pediatric patients. After leukemia, brain malignancies are the second most common in the pediatric population and first in incidences concerning solid tumors. This study was designed on the basis of 14 pediatric patients hospitalized at Children's Memorial Health Institute in Warsaw, Poland, due to p-HGG treatment. All the patients had a histopathological diagnosis performed by an experienced neuropathologist according to WHO guidelines (WHO 2016 Grade IV Glioblastoma). A significant correlation was found between the miR-155 concentration and the level of PD-L1 expression in p-HGG tumor tissue. Very few reports have indicated PD-L1 expression in pediatric patients.