Pediatric glioblastoma

Despite this rarity, it is apparent from the limited number of publications that pediatric glioblastoma is quite distinct from their adult counterparts. The differences pertain to the molecular genetics, effectiveness of the adjuvant therapies, and possibly the prognosis after treatment. With a plethora of path-breaking translational research coming through in recent times, a host of new information is now available on pediatric glioblastomas that holds great promise as far as the future treatment options are concerned ¹⁾

In contrast to adult GBM, few molecular prognostic markers for the pediatric counterpart have been established.

Some anaplastic pleomorphic xanthoastrocytomas (PXA) were reported to have extremely poor prognosis which showed a type of pediatric glioblastoma (GBM) molecular profile. Recent integrated molecular classification for primary central nervous system tumors proposed some differences between histological and molecular features. Herein, in a genome-wide molecular analysis, Nakamura et al., showed an extreme aggressive anaplastic PXA that resulted in a pediatric GBM molecular profile. A full implementation of the molecular approach is the key to predict prognosis and decide the treatment strategy for anaplastic PXA ²⁾.

Korshunov et al. investigated the prognostic significance of genomic and epigenetic alterations through molecular analysis of 202 pedGBM (1-18 years) with comprehensive clinical annotation. Routinely prepared formalin-fixed paraffin-embedded tumor samples were assessed for genome-wide DNA methylation profiles, with known candidate genes screened for alterations via direct sequencing or FISH. Unexpectedly, a subset of histologically diagnosed GBM (n = 40, 20 %) displayed methylation profiles similar to those of either low-grade gliomas or pleomorphic xanthoastrocytomas (PXA). These tumors showed a markedly better prognosis, with molecularly PXA-like tumors frequently harboring BRAF V600E mutations and 9p21 (CDKN2A) homozygous deletion. The remaining 162 tumors with pedGBM molecular signatures comprised four subgroups: H3.3 G34-mutant (15 %), H3.3/H3.1 K27-mutant (43 %), IDH1-mutant (6 %), and H3/IDH wild-type (wt) GBM (36 %). These subgroups were associated with specific cytogenetic aberrations, MGMT methylation patterns and clinical outcomes. Analysis of follow-up data identified a set of biomarkers feasible for use in risk stratification: pedGBM with any oncogene amplification and/or K27M mutation (n = 124) represents a particularly unfavorable group, with 3-year overall survival (OS) of 5 %, whereas tumors without these markers (n = 38) define a more favorable group (3-year OS ~70 %).Combined with the lower grade-like lesions, almost 40 % of pedGBM cases had distinct molecular features associated with a more favorable outcome. This refined prognostication method for pedGBM using a molecular risk algorithm may allow for improved therapeutic choices and better planning of clinical trial stratification for this otherwise devastating disease ³⁾

Total resection and receiving chemotherapy adjuvant to radiation or chemoradiation (CRT) are most closely associated with improved progression free survival (PFS) and overall survival (OS). For higher risk incompletely resected patients, temozolomide use and treatment intensification with concurrent CRT, adjuvant chemotherapy, and higher radiation dose were associated with improved outcomes ⁴⁾.

Bevacizumab and irinotecan are a promising regimen for pediatric cases of recurrent glioblastoma after gross-total resection, although the optimal treatment schedule must be determined on a patient-by-patient basis ⁵⁾.

A rare case of primary pediatric glioblastoma multiforme in a 7-year-old girl with Turner’s syndrome is reported, and various aspects regarding clinical and pathophysiological issues have been discussed. Although Turner’s syndrome is not one of the congenital chromosomal abnormalities which demand routine CNS screening, neurological assessment may be of value in those with relevant clinical findings ⁶⁾.