Project description:We performed gene expression profiling on 151 paraffin-embedded PLGGs from different locations, ages, histological subtypes as well as BRAF genetic status We also compared molecular differences to normal pediatric brain expression profiles to observe whether those patterns were mirrored in normal brain expression. We analyzed the expression of 6,100 genes among 151 FFPE pediatric and 15 FFPE adult low-grade gliomas and analyzed how the expression patterns changes with location, age, histology and BRAF genomic status and how those differences were mirrored in normal brain expression. The values in the sample 'characteristics' columns represent; Location; SUP= Supratentorial, INF= Infratentorial Histology; PA= pilocytic astrocytoma, GG= ganglioglioma, DNT= dysembryoplastic neuroepithelial tumor, OD= oligodendroglial tumors, NOS= not otherwise specified tumors BRAF status; DUP= BRAF duplication, MUT= BRAF V600E mutation, WT= wild type, ND= not determined Primary or recurrent tumor; P=primary, R=recurrent Primary tumor that further progressed; 1=yes, 0=no, _=recurrent tumors only
Project description:We report an infantile case of midline ‘supratentorial ependymoma ZFTA fusion-positive’ involving both the infra- and the supra-tentorial compartments (i.e., cerebellar vermis, pons and midbrain). The radiological features, i.e., the upward displacement and compression of the supratentorial anatomical structures and the infiltrative margins of the tumour towards the cerebellar vermis, suggested an infratentorial origin of the lesion with secondary involvement of the supratentorial compartment. This case adds to the limited literature of non-hemispheric ‘supratentorial ependymoma ZFTA fusion-positive’ occurring in midline structures, both supratentorial (pineal region, thalamus) and infratentorial (cervico-medullary region and spinal cord), and in the cerebellum. These cases highlight the need to consider this entity in the differential diagnosis of paediatric non-hemispheric lesions and raise the question of whether the inclusion of the location within the WHO definition of this tumour type may be too restrictive
Project description:Low grade gliomas (LGG; WHO grade 2 astrocytomas, oligodendrogliomas and oligoastrocytomas) account for about 25% of diffuse gliomas. Most occur in young adults between the ages of 30 and 45 years, and are usually only diagnosed after a seizure. In general, they can be characterised by a long period of continuous slow growth, followed by malignant transformation that will be the cause of death up to 25 years after onset. However, there is a significant number of patients for whom malignant progression is more rapid, with mortality observed within 5 years. This suggests that, as with other tumour types, there may be different subtypes of LGG with specific prognosis. It follows that being able to identify these subtypes may permit better patient stratification and aid targeted treatments. Until recently, our understanding of the variables involved in patient prognosis included the type of tumour oligodendroglial tumours indicate better prognosis than oligoastrocytic or astrocytic and presence of the 1p-19q co-deletion. In addition, the recent discovery of mutations in IDH1&2 in the majority of LGGs provided another means of stratifying patients, while offering an important insight into their biology. However, we still understand very little of the biology behind the genesis and progression of the 70-80% of LGG that bear IDH1&2 mutations, let alone the remaining IDH wild-type tumours.
Project description:Introduction: The EORTC22033-26033 clinical trial investigated whether initial temozolomide (TMZ) chemotherapy confers survival advantage compared to radiotherapy (RT) in low grade glioma patients. In this study we performed gene expression profiling on tissues from this trial in order to identify markers associated with progression free survival and treatment response in this well-defined cohort of patients. Methods: Gene expression profiling, performed on 195 samples, was used to assign tumors to one of six intrinsic glioma subtypes (IGS; molecularly similar tumors predefined by unsupervised gene expression analysis) and to extract the cellular composition of immune infiltrates. DNA copy number changes were determined on samples assigned to IGS-16. Results: We confirm that IGS-subtypes are prognostic in EORTC22033-26033 clinical trial samples. Specific genetic changes segregate in distinct IGS subtypes: most samples assigned to IGS-9 have IDH-mutations combined with 1p19q codeletion, samples assigned to IGS-17 have IDH-mutations with intact 1p19q chromosomal arms and samples assigned to other intrinsic subtypes often are IDH-wildtype and 1p19q intact. A trend towards benefit from RT compared to TMZ was observed for samples assigned to IGS-9 (HR for TMZ is 1.90, 95% CI [0.95, 3.80], P=0.065), but not for samples assigned to IGS-17 (HR for TMZ vs RT is 0.87, 95% CI[0.50, 1.51], P=0.62). We did not identify genes significantly associated with progression free survival (PFS) within intrinsic subtypes, though follow-up time is limited. We also show that LGGs and GBMs differ in their immune-infiltrate with LGGs having higher suppressor and lower effector cell populations compared to GBMs. This suggests that LGGs are less amenable to checkpoint inhibitor type immune therapies than GBMs. Gene expression analysis and copy number analysis also identified one patient with a pilocytic astrocytoma (PA). Conclusion: Intrinsic glioma subtypes are prognostic for PFS in EORTC22033-26033 clinical trial samples.
Project description:Leveraging RNA sequencing deconvolution, single cell RNA sequencing and protein-based analyses of Nf1OPG, we define the stromal cell composition during mouse Nf1-OPG evolution, as well as in human pediatric low-grade gliomas (LGGs). We show that T cells and microglia are the main non-neoplastic immune cell populations in both murine and human LGGs.
Project description:20% of patients affected with diffuse low-grade brain tumors have high cell density foci harboring higher KI67 index and DNA alterations. These foci may represent tumor progression towards high-grade gliomas. Here we performed transcriptome analysis of those foci vs adjacent tumoral tissues dissected from formalin fixed and paraffin embedded blocks.