Molecular biomarkers in pediatric glial tumors: a needed wind of change

Glial tumors of the central nervous system (CNS) are the leading cause of cancer-related death and morbidity in children. Their diagnosis/prognosis relies mainly on clinical and histopathological factors. However, pathological grading is particularly challenging as there is substantial molecular heterogeneity in pediatric CNS tumors, which results in variable biological behavior in tumors with potentially identical histological diagnoses or limited reliable measures of classification for given subgroups. Novel molecular markers/pathways identified by integrated genomic/transcriptomic/epigenomic studies of cohorts of pediatric gliomas are revolutionizing this field and are summarized herein.

Studies of pediatric gliomas have identified unexpected oncogenic pathways implicated in gliomagenesis. These range from a single pathway/molecule defect such as abnormalities of the mitogen-activated-protein-kinase pathway considered to be a hallmark of pilocytic astrocytomas, to alterations in epigenomic modulators in higher-grade tumors. Importantly, the type, timing, and spatial clustering of these molecular alterations provide a better understanding of the pathogenesis of gliomas and critical markers for therapy that will help refine pathological grading.

Reappraisal of glioma classification using these novel biomarkers will likely change practice toward molecular pathology and their integration into clinical trials will enable personalized therapies based on the molecular fingerprint of individual tumors.