An Integrated Set of Pediatric High Grade Glioma Resources for Translational Studies

Abstract

Pediatric high grade glioma (pHGG) remains a fatal disease. Increasing the number of patient derived tumor models and reagents will encourage research in pHGG and support the translation of basic science research discoveries. This work describes a recent multi-institution initiative to provide such a resource. METHODS: pHGG tumors with associated clinical data were prospectively collected and sequenced through the Children’s Brain Tumor Tissue Consortium (CBTTC) and Pediatric Brain Tumor Atlas (PBTA) with data deposited into PedcBioPortal for easy access and visualization. Primary tumor was dissociated and cultured to create both adherent and glioma stem cell lines analyzed by targeted and WGS/RNA sequencing. A tissue microarray (TMA) of primary pHGG tumors was created and examined by immunohistochemistry.

The pHGG set included 81 collection events (70 patients, 54% at diagnosis, median age of 11 yrs, 52% female, 43% hemispheric). Analysis of somatic mutations and copy number alterations of known glioma genes were of expected distribution (36% H3.3, 47% TP53, 24% ATRX and 7% BRAF V600E variants). There were rare germline variants in mismatch repair genes with resultant tumor hyper-mutation. At least one established adherent and/or suspension glioma stem cell line was generated from 22 (31%) patients and validated by targeted sequencing for driver pHGG mutations. A subset of lines had WGS and RNAseq profiling which computationally clustered with their parental primary tumors. The lines’ cell biology makeup and in vivo tumor formation was also evaluated. A pHGG TMA (n=77), including 37 (53%) of the sequenced pHGG tumors, showed concordance with mutation status when stained for ATRX, H3.3 K27M and TP53.

The CBTTC and PBTA have created a freely available integrated resource of characterized pHGG primary tumors, corresponding cell lines and archival fixed tissue to advance translational research for pHGG.