Clinicopathological and molecular landscape of 5-year IDH-wild-type glioblastoma survivors: A multicentric retrospective study.

Five-year glioblastoma (GBM) survivors (LTS) are the minority of the isocitrate dehydrogenase (IDH)-wild-type GBM patients, and their molecular fingerprint is still largely unexplored. This multicenter retrospective study analyzed a large LTS-GBM cohort from nine Italian institutions and molecularly characterized a subgroup of patients by mutation, DNA methylation (DNAm) and copy number variation (CNV) profiling, comparing it to standard survival GBM. Mutation scan allowed the identification of pathogenic variants in most cases, showing a similar mutational spectrum in both groups, and highlighted TP53 as the most commonly mutated gene in the LTS group. We confirmed DNAm as a valuable tool for GBM classification with a diagnostic refinement by using brain tumor classifier v12.5. LTS were more heterogeneous with more cases classified as diffuse pediatric high-grade glioma subtypes and having peculiar CNVs. We observed a global higher methylation in CpG islands and in gene promoters of LTS with methylation levels of distinct gene promoters correlating with prognosis.

Expression analysis of NF1-mutated alleles in a rare compound heterozygous spinal NF1 patient by digital PCR.

BACKGROUD: Neurofibromatosis type 1 (NF1) is a heterogeneous neurocutaneous disorder. Spinal neurofibromatosis (SNF) is a distinct clinical entity of NF1, characterized by bilateral neurofibromas involving all spinal nerve roots. Although both forms are caused by intragenic heterozygous variants of NF1, missense variants have been associated with SNF, according to a dominant inheritance model causing haploinsufficiency. Most patients carry pathogenic variants in one of the NF1 alleles; nevertheless, patients with both NF1-mutated copies have been described. Interestingly, all NF1 variants carried by the known SNF compound heterozygotes were missense/splicing variants or in-frame insertion-deletions. AIMS: To investigate whether there is a differential expression of NF1 variant alleles in an NF1 compound heterozygous SNF patient possibly contributing to clinical phenotype. MATERIALS & METHODS: We performed an allele-specific expression study, by chip-based digital PCR, in an SNF family carrying two NF1 missense variants. We evaluated the expression levels of the two NF1-mutated alleles both carried by the compound heterozygous SNF patient and his relatives. RESULTS: Both alleles were expressed at comparable levels in the patient and hyper-expressed compared to the wild-type alleles of healthy controls. DISCUSSION: Here we provide new insights into expression studies of NF1-mutated transcripts suggesting that a novel pathogenetic mechanism, caused by gain-of-function variants, could be associated with SNF. CONCLUSIONS: Further studies should be performed in larger cohorts, opening new perspectives in the NF1 pathogenesis comprehension.

European Cancer Organisation Essential Requirements for Quality Cancer Care: Adult glioma.

European Cancer Organisation Essential Requirements for Quality Cancer Care (ERQCCs) are explanations of the organisation and actions necessary to provide high-quality care to patients with a specific cancer type. They are compiled by a working group of European experts representing disciplines involved in cancer care, and provide oncology teams, patients, policymakers and managers with an overview of the essential requirements in any healthcare system. The focus here is on adult glioma. Gliomas make up approximately 80% of all primary malignant brain tumours. They are highly diverse and patients can face a unique cognitive, physical and psychosocial burden, so personalised treatments and support are essential. However, management of gliomas is currently very heterogeneous across Europe and there are only few formally-designated comprehensive cancer centres with brain tumour programmes. To address this, the ERQCC glioma expert group proposes frameworks and recommendations for high quality care, from diagnosis to treatment and survivorship. Wherever possible, glioma patients should be treated from diagnosis onwards in high volume neurosurgical or neuro-oncology centres. Multidisciplinary team working and collaboration is essential if patients' length and quality of life are to be optimised.

New insights into the molecular basis of spinal neurofibromatosis type 1.

Spinal neurofibromatosis (SNF) is a form of neurofibromatosis type 1 (NF1) characterized by bilateral neurofibromas involving all spinal roots. The pathogenic mechanisms determining the SNF form are currently unknown. To verify the presence of genetic variants possibly related to SNF or classic NF1, we studied 106 sporadic NF1 and 75 SNF patients using an NGS panel of 286 genes encoding RAS pathway effectors and neurofibromin interactors and evaluated the expression of syndecans (SDC1, SDC2, SDC3, SDC4), the NF1 3' tertile interactors, by quantitative real-time PCR. We previously identified 75 and 106 NF1 variants in SNF and NF1 cohorts, respectively. The analysis of the distribution of pathogenic NF1 variants in the three NF1 tertiles showed a significantly higher prevalence of NF1 3' tertile mutations in SNF than in the NF1 cohort. We hypothesized a potential pathogenic significance of the 3' tertile NF1 variants in SNF. The analysis of syndecan expression on PBMCs RNAs from 16 SNF, 16 classic NF1 patients and 16 healthy controls showed that the expression levels of SDC2 and SDC3 were higher in SNF and NF1 patients than in controls; moreover, SDC2, SDC3 and SDC4 were significantly over expressed in patients mutated in the 3' tertile compared to controls. Two different mutational NF1 spectra seem to characterize SNF and classic NF1, suggesting a pathogenic role of NF1 3' tertile and its interactors, syndecans, in SNF. Our study, providing new insights on a possible role of neurofibromin C-terminal in SNF, could address effective personalized patient management and treatments.

Genome-wide profiling of patient-derived glioblastoma stem-like cells reveals recurrent genetic and transcriptomic signatures associated with brain tumors.

PURPOSE: Patient-derived cancer cell lines can be very useful to investigate genetic as well as epigenetic mechanisms of transformation and to test new drugs. In this multi-centric study, we performed genomic and transcriptomic characterization of a large set of patient-derived glioblastoma (GBM) stem-like cells (GSCs). METHODS: 94 (80 I surgery/14 II surgery) and 53 (42 I surgery/11 II surgery) GSCs lines underwent whole exome and trascriptome analysis, respectively. RESULTS: Exome sequencing revealed TP53 as the main mutated gene (41/94 samples, 44%), followed by PTEN (33/94, 35%), RB1 (16/94, 17%) and NF1 (15/94, 16%), among other genes associated to brain tumors. One GSC sample bearing a BRAF p.V600E mutation showed sensitivity in vitro to a BRAF inhibitor. Gene Ontology and Reactome analysis uncovered several biological processes mostly associated to gliogenesis and glial cell differentiation, S - adenosylmethionine metabolic process, mismatch repair and methylation. Comparison of I and II surgery samples disclosed a similar distribution of mutated genes, with an overrepresentation of mutations in mismatch repair, cell cycle, p53 and methylation pathways in I surgery samples, and of mutations in receptor tyrosine kinase and MAPK signaling pathways in II surgery samples. Unsupervised hierarchical clustering of RNA-seq data produced 3 clusters characterized by distinctive sets of up-regulated genes and signaling pathways. CONCLUSION: The availability of a large set of fully molecularly characterized GCSs represents a valuable public resource to support the advancement of precision oncology for the treatment of GBM.

Cognitive and Behavioral Outcome of Pediatric Low-Grade Central Nervous System Tumors Treated Only with Surgery: A Single Center Experience.

BACKGROUND: The present mono-institutional report aimed to describe the cognitive and behavioral outcomes of low-grade central nervous system (CNS) tumors in a cohort of children treated exclusively with surgical intervention. METHODS: Medical records from 2000-2020 were retrospectively analyzed. We included 38 children (mean age at first evaluation 8 years and 3 months, 16 females) who had undergone presurgical cognitive-behavioral evaluation and/or at least 6 months follow-up. Exclusion criteria were a history of traumatic brain injury, stroke, cerebral palsy or cancer-predisposing syndromes. RESULTS: The sample presented cognitive abilities and behavioral functioning in the normal range, with weaknesses in verbal working memory and processing speed. The obtained results suggest that cognitive and behavioral functioning is related to pre-treatment variables (younger age at symptoms' onset, glioneuronal histological type, cortical location with preoperative seizures), timing of surgery and seizure control after surgery, and is stable when controlling for a preoperative cognitive and behavioral baseline. Younger age at onset is confirmed as a particular vulnerability in determining cognitive sequelae, and children at older ages or at longer postsurgical follow-up are at higher risk for developing behavioral disturbances. CONCLUSIONS: Timely treatment is an important factor influencing the global outcome and daily functioning of the patients. Preoperative and regular postsurgical cognitive and behavioral assessment, also several years after surgery, should be included in standard clinical practices.

CSF-based liquid biopsy pointing to a diagnosis of diffuse glioma in a patient with supposed neurodegenerative disorder.

INTRODUCTION: The differential diagnosis of brain diseases becomes challenging in cases where imaging is not sufficiently informative, and surgical biopsy is impossible or unacceptable to the patient. METHODS: An elderly patient with progressive short-term memory loss and cognitive impairment presented with a normal brain CT scan, a brain FDG-PET that indicated symmetrical deterioration of the white matter in the frontal lobes, and inconclusive results of a molecular marker analysis of suspected dementia in cerebrospinal fluid (CSF). Brain MRI suggested the diagnosis of lower grade glioma. The patient refused surgical biopsy. In order to investigate whether somatic mutations associated with gliomas existed, we performed a "liquid biopsy" by the targeted sequencing of cell-free DNA (cfDNA) from his CSF. RESULTS: Deep sequencing of the cfDNA from CSF revealed somatic mutations characteristically found in gliomas, including mutations of the TP53 (Arg282Trp), BRAF (Val600Glu), and IDH1 (Arg132His) genes. The patient is currently treated with temozolomide, and his clinical and MRI findings suggest the stabilization of his disease. CONCLUSION: Neurological patients may benefit from liquid biopsy diagnostic work-up as it can reveal therapeutically targetable mutations.

Sporadic spinal psammomatous malignant melanotic nerve sheath tumor: A case report and literature review.

Background: Sporadic Spinal Psammomatous Malignant Melanotic Nerve Sheath Tumor (SSP-MMNST) is a rare subgroup of peripheral nerve sheath tumors arising along the spine. Only a few reports of SSP-MMNST have been described. In this paper, we review the literature on SSP-MMNST focusing on clinical, and diagnostic features, as well as investigating possible pathogenetic mechanisms to better implement therapeutic strategies. We also report an illustrative case of a young female presenting with cervicobrachial pain due to two SSP-MMNSTs arising from C5-6 right spinal roots. Case description: We report a case of a 28-year-old woman presenting with right arm weakness and dysesthesia. Clinical examination and neuroimaging were performed, and, following surgical removal of both lesions, a histological diagnosis of SSP-MMNST was obtained. Results: The literature review identified 21 eligible studies assessing 23 patients with SSP-MMNST, with a mean onset age of 41 years and a slight male gender preference. The lumbar district was the most involved spinal segment. Gross-total resection (GTR) was the treatment of choice in all amenable cases, followed in selected cases with residual tumor by adjuvant radiotherapy or chemotherapy. The metastatic and recurrence rates were 31.58% and 36.8%, respectively. Conclusion: Differently from common schwannomas, MMNST represents a rare disease with known recurrence and metastatization propensity. As reported in our review, SSP-MMNST has a greater recurrence rate when compared to other forms of spinal MMNST, raising questions about the greater aggressiveness of the former. We also found that residual disease is related to a higher risk of systemic disease spreading. This metastatic potential, usually associated with primary lumbar localization, is characterized by a slight male prevalence. Indeed, whenever GTR is unachievable, considering the higher recurrence rate, adjuvant radiation therapy should be taken into consideration.

Involvement of GABAergic Interneuron Subtypes in 4-Aminopyridine-Induced Seizure-Like Events in Mouse Entorhinal Cortex in Vitro.

Single-unit recordings performed in temporal lobe epilepsy patients and in models of temporal lobe seizures have shown that interneurons are active at focal seizure onset. We performed simultaneous patch-clamp and field potential recordings in entorhinal cortex slices of GAD65 and GAD67 C57BL/6J male mice that express green fluorescent protein in GABAergic neurons to analyze the activity of specific interneuron (IN) subpopulations during acute seizure-like events (SLEs) induced by 4-aminopyridine (4-AP; 100 µm). IN subtypes were identified as parvalbuminergic (INPV, n = 17), cholecystokinergic (INCCK), n = 13], and somatostatinergic (INSOM, n = 15), according to neurophysiological features and single-cell digital PCR. INPV and INCCK discharged at the start of 4-AP-induced SLEs characterized by either low-voltage fast or hyper-synchronous onset pattern. In both SLE onset types, INSOM fired earliest before SLEs, followed by INPV and INCCK discharges. Pyramidal neurons became active with variable delays after SLE onset. Depolarizing block was observed in ∼50% of cells in each INs subgroup, and it was longer in IN (∼4 s) than in pyramidal neurons (<1 s). As SLE evolved, all IN subtypes generated action potential bursts synchronous with the field potential events leading to SLE termination. High-frequency firing throughout the SLE occurred in one-third of INPV and INSOM We conclude that entorhinal cortex INs are very active at the onset and during the progression of SLEs induced by 4-AP. These results support earlier in vivo and in vivo evidence and suggest that INs have a preferential role in focal seizure initiation and development.SIGNIFICANCE STATEMENT Focal seizures are believed to result from enhanced excitation. Nevertheless, we and others demonstrated that cortical GABAergic networks may initiate focal seizures. Here, we analyzed for the first time the role of different IN subtypes in seizures generated by 4-aminopyridine in the mouse entorhinal cortex slices. We found that in this in vitro focal seizure model, all IN types contribute to seizure initiation and that INs precede firing of principal cells. This evidence is in agreement with the active role of GABAergic networks in seizure generation.

LZTR1 Mutation Mediates Oncogenesis through Stabilization of EGFR and AXL.

LZTR1 is the substrate-specific adaptor of a CUL3-dependent ubiquitin ligase frequently mutated in sporadic and syndromic cancer. We combined biochemical and genetic studies to identify LZTR1 substrates and interrogated their tumor-driving function in the context of LZTR1 loss-of-function mutations. Unbiased screens converged on EGFR and AXL receptor tyrosine kinases as LZTR1 interactors targeted for ubiquitin-dependent degradation in the lysosome. Pathogenic cancer-associated mutations of LZTR1 failed to promote EGFR and AXL degradation, resulting in dysregulated growth factor signaling. Conditional inactivation of Lztr1 and Cdkn2a in the mouse nervous system caused tumors in the peripheral nervous system including schwannoma-like tumors, thus recapitulating aspects of schwannomatosis, the prototype tumor predisposition syndrome sustained by LZTR1 germline mutations. Lztr1- and Cdkn2a-deleted tumors aberrantly accumulated EGFR and AXL and exhibited specific vulnerability to EGFR and AXL coinhibition. These findings explain tumorigenesis by LZTR1 inactivation and offer therapeutic opportunities to patients with LZTR1-mutant cancer. SIGNIFICANCE: EGFR and AXL are substrates of LZTR1-CUL3 ubiquitin ligase. The frequent somatic and germline mutations of LZTR1 in human cancer cause EGFR and AXL accumulation and deregulated signaling. LZTR1-mutant tumors show vulnerability to concurrent inhibition of EGFR and AXL, thus providing precision targeting to patients affected by LZTR1-mutant cancer. This article is highlighted in the In This Issue feature, p. 517.

Development of A Radiomic Model for MGMT Promoter Methylation Detection in Glioblastoma Using Conventional MRI.

The methylation of the O6-methylguanine-DNA methyltransferase (MGMT) promoter is a molecular marker associated with a better response to chemotherapy in patients with glioblastoma (GB). Standard pre-operative magnetic resonance imaging (MRI) analysis is not adequate to detect MGMT promoter methylation. This study aims to evaluate whether the radiomic features extracted from multiple tumor subregions using multiparametric MRI can predict MGMT promoter methylation status in GB patients. This retrospective single-institution study included a cohort of 277 GB patients whose 3D post-contrast T1-weighted images and 3D fluid-attenuated inversion recovery (FLAIR) images were acquired using two MRI scanners. Three separate regions of interest (ROIs) showing tumor enhancement, necrosis, and FLAIR hyperintensities were manually segmented for each patient. Two machine learning algorithms (support vector machine (SVM) and random forest) were built for MGMT promoter methylation prediction from a training cohort (196 patients) and tested on a separate validation cohort (81 patients), based on a set of automatically selected radiomic features, with and without demographic variables (i.e., patients' age and sex). In the training set, SVM based on the selected radiomic features of the three separate ROIs achieved the best performances, with an average of 83.0% (standard deviation: 5.7%) for accuracy and 0.894 (0.056) for the area under the curve (AUC) computed through cross-validation. In the test set, all classification performances dropped: the best was obtained by SVM based on the selected features extracted from the whole tumor lesion constructed by merging the three ROIs, with 64.2% (95% confidence interval: 52.8-74.6%) accuracy and 0.572 (0.439-0.705) for AUC. The performances did not change when the patients' age and sex were included with the radiomic features into the models. Our study confirms the presence of a subtle association between imaging characteristics and MGMT promoter methylation status. However, further verification of the strength of this association is needed, as the low diagnostic performance obtained in this validation cohort is not sufficiently robust to allow clinically meaningful predictions.

Characterization of 22q12 Microdeletions Causing Position Effect in Rare NF2 Patients with Complex Phenotypes.

Neurofibromatosis type 2 is an autosomal dominant tumor-prone disorder mainly caused by NF2 point mutations or intragenic deletions. Few individuals with a complex phenotype and 22q12 microdeletions have been described. The 22q12 microdeletions' pathogenic effects at the genetic and epigenetic levels are currently unknown. We here report on 22q12 microdeletions' characterization in three NF2 patients with different phenotype complexities. A possible effect of the position was investigated by in silico analysis of 22q12 topologically associated domains (TADs) and regulatory elements, and by expression analysis of 12 genes flanking patients' deletions. A 147 Kb microdeletion was identified in the patient with the mildest phenotype, while two large deletions of 561 Kb and 1.8 Mb were found in the other two patients, showing a more severe symptomatology. The last two patients displayed intellectual disability, possibly related to AP1B1 gene deletion. The microdeletions change from one to five TADs, and the 22q12 chromatin regulatory landscape, according to the altered expression levels of four deletion-flanking genes, including PIK3IP1, are likely associated with an early ischemic event occurring in the patient with the largest deletion. Our results suggest that the identification of the deletion extent can provide prognostic markers, predictive of NF2 phenotypes, and potential therapeutic targets, thus overall improving patient management.

A Translational Approach to Spinal Neurofibromatosis: Clinical and Molecular Insights from a Wide Italian Cohort.

Spinal neurofibromatosis (SNF), a phenotypic subclass of neurofibromatosis 1 (NF1), is characterized by bilateral neurofibromas involving all spinal roots. In order to deepen the understanding of SNF's clinical and genetic features, we identified 81 patients with SNF, 55 from unrelated families, and 26 belonging to 19 families with at least 1 member affected by SNF, and 106 NF1 patients aged >30 years without spinal tumors. A comprehensive NF1 mutation screening was performed using NGS panels, including NF1 and several RAS pathway genes. The main features of the SNF subjects were a higher number of internal neurofibromas (p < 0.001), nerve root swelling (p < 0.001), and subcutaneous neurofibromas (p = 0.03), while hyperpigmentation signs were significantly less frequent compared with the classical NF1-affected cohorts (p = 0.012). Fifteen patients underwent neurosurgical intervention. The histological findings revealed neurofibromas in 13 patients and ganglioneuromas in 2 patients. Phenotypic variability within SNF families was observed. The proportion of missense mutations was higher in the SNF cases than in the classical NF1 group (21.40% vs. 7.5%, p = 0.007), conferring an odds ratio (OR) of 3.34 (CI = 1.33−10.78). Two unrelated familial SNF cases harbored in trans double NF1 mutations that seemed to have a subclinical worsening effect on the clinical phenotype. Our study, with the largest series of SNF patients reported to date, better defines the clinical and genetic features of SNF, which could improve the management and genetic counseling of NF1.

High tumor mutational burden and T-cell activation are associated with long-term response to anti-PD1 therapy in Lynch syndrome recurrent glioblastoma patient.

BACKGROUND: Glioblastomas (GBMs) in patients harboring somatic or germinal mutations of mismatch-repair (MMR) genes exhibit a hypermutable phenotype. Here, we describe a GBM patient with increased tumor mutational burden and germline MMR mutations, treated using anti-PD1 therapy. METHODS: A woman with newly diagnosed GBM (nGBM) was treated by surgery, radiotherapy, and temozolomide. The tumor recurred after 13 months leading to a second surgery and treatment with nivolumab. Whole-exome sequencing was performed on the nGBM, recurrent GBM (rGBM), and blood. Immune infiltration was investigated by immunohistochemistry and the immune response in the blood during treatment was analyzed by flow cytometry. RESULTS: High density of infiltrating CD163 + cells was found in both GBM specimens. Large numbers of CD3 + and CD8 + T cells were homogeneously distributed in the nGBM. The infiltration of CD4 + T cells and a different CD8 + T cell density were observed in the rGBM. Both GBM shared 12,431 somatic mutations, with 113 substitutions specific to the nGBM and 1,683 specific to the rGBM. Germline variants included pathogenic mutation in the MSH2 (R359S) gene, suggesting the diagnosis of Lynch syndrome. Systemic immunophenotyping revealed the generation of CD8 + T memory cells and persistent activation of CD4 + T cells. The patient is still receiving nivolumab 68 months after the second surgery. CONCLUSIONS: Our observations indicate that the hypermutator phenotype associated with germinal mutations of MMR genes and abundant T-cell infiltration contributes to a durable clinical benefit sustained by a persistent and robust immune response during anti-PD1 therapy.

Simultaneous Detection of NF1, SPRED1, LZTR1, and NF2 Gene Mutations by Targeted NGS in an Italian Cohort of Suspected NF1 Patients.

Neurofibromatosis type 1 (NF1) displays overlapping phenotypes with other neurocutaneous diseases such as Legius Syndrome. Here, we present results obtained using a next generation sequencing (NGS) panel including NF1, NF2, SPRED1, SMARCB1, and LZTR1 genes on Ion Torrent. Together with NGS, the Multiplex Ligation-Dependent Probe Amplification Analysis (MLPA) method was performed to rule out large deletions/duplications in NF1 gene; we validated the MLPA/NGS approach using Sanger sequencing on DNA or RNA of both positive and negative samples. In our cohort, a pathogenic variant was found in 175 patients; the pathogenic variant was observed in NF1 gene in 168 cases. A SPRED1 pathogenic variant was also found in one child and in a one year old boy, both NF2 and LZTR1 pathogenic variants were observed; in addition, we identified five LZTR1 pathogenic variants in three children and two adults. Six NF1 pathogenic variants, that the NGS analysis failed to identify, were detected on RNA by Sanger. NGS allows the identification of novel mutations in five genes in the same sequencing run, permitting unambiguous recognition of disorders with overlapping phenotypes with NF1 and facilitating genetic counseling and a personalized follow-up.

Clinical, molecular, and radiomic profile of gliomas with FGFR3-TACC3 fusions.

BACKGROUND: Actionable fibroblast growth factor receptor 3 (FGFR3)-transforming acidic coiled-coil protein 3 fusions (F3T3) are found in approximately 3% of gliomas, but their characteristics and prognostic significance are still poorly defined. Our goal was to characterize the clinical, radiological, and molecular profile of F3T3 positive diffuse gliomas. METHODS: We screened F3T3 fusion by real-time (RT)-PCR and FGFR3 immunohistochemistry in a large series of gliomas, characterized for main genetic alterations, histology, and clinical evolution. We performed a radiological and radiomic case control study, using an exploratory and a validation cohort. RESULTS: We screened 1162 diffuse gliomas (951 unselected cases and 211 preselected for FGFR3 protein immunopositivity), identifying 80 F3T3 positive gliomas. F3T3 was mutually exclusive with IDH mutation (P < 0.001) and EGFR amplification (P = 0.01), defining a distinct molecular cluster associated with CDK4 (P = 0.04) and MDM2 amplification (P = 0.03). F3T3 fusion was associated with longer survival for the whole series and for glioblastomas (median overall survival was 31.1 vs 19.9 mo, P = 0.02) and was an independent predictor of better outcome on multivariate analysis.F3T3 positive gliomas had specific MRI features, affecting preferentially insula and temporal lobe, and with poorly defined tumor margins. F3T3 fusion was correctly predicted by radiomics analysis on both the exploratory (area under the curve [AUC] = 0.87) and the validation MRI (AUC = 0.75) cohort. Using Cox proportional hazards models, radiomics predicted survival with a high C-index (0.75, SD 0.04), while the model combining clinical, genetic, and radiomic data showed the highest C-index (0.81, SD 0.04). CONCLUSION: F3T3 positive gliomas have distinct molecular and radiological features, and better outcome.

Gliomatosis cerebri (GC) or GC-like? A picture to be reconsidered in neuro-oncology based on large retrospective analysis of GC series.

INTRODUCTION: Gliomatosis cerebri (GC), defined until 2016 as a distinct astrocytic glioma entity, has been removed from the 2016 World Health Organization classification of tumors of the central nervous system. However, its identity is still debated. MATERIALS AND METHODS: We retrospectively present 122 patients, including a subgroup with histology confirmation (n = 75, cohort b). RESULTS: Radiological features showed extension limited to 3 lobes in 31%; bilateral, midline, and basal ganglia and subtentorial involvement in 95%, 52%, 84%, and 60%, respectively; and contrast enhancement in 59.5%. Perioperative mortality occurred in 4%. Histology concluded for grades II, III, and IV, respectively, in 31%, 35%, and 22% (not specified in 12%). Thirty-one percent had isocitrate dehydrogenase (IDH) 1 mutation. Treatments included radiotherapy in 51.2% and chemotherapy in 74.5%. Median overall survival was 17 months. Negative prognostic factors for survival were older age, poorer Karnofsky Performance Scale (KPS), subtentorial, midline and disseminated disease, and lack of chemotherapy, at univariate analysis. At multivariate analysis, KPS ≥ 80, chemotherapy, and subtentorial and disseminated disease remained prognostic (p < 0.0001). For cohort b, same prognostic factors were confirmed, except for midline location, at univariate analysis; at multivariate analysis, only KPS ≥ 80 and chemotherapy remained prognostic (p < 0.0001). CONCLUSION: We described clinical, neuroimaging, management, and histomolecular features of one of the largest GC series. We identified KPS ≥ 80, radiological pattern as subtentorial localization and dissemination, and chemotherapy as prognostic factors, at multivariate analysis. Planning prospective study, associated to focused genetic assays, could help to clarify if GC has specific features that may result in the identification as a separate entity from other gliomas.

The Search for Molecular Markers in a Gene-Orphan Case Study of a Pediatric Spinal Cord Pilocytic Astrocytoma.

BACKGROUND/AIM: We herein presented a case of pediatric spinal cord pilocytic astrocytoma diagnosed on the basis of histopathological and clinical findings. MATERIALS AND METHODS: Given the paucity of data on genetic features for this tumor, we performed exome, array CGH and RNA sequencing analysis from nucleic acids isolated from a unique and not repeatable very small amount of a formalin-fixed, paraffin-embedded (FFPE) specimen. RESULTS: DNA mutation analysis, comparing tumor and normal lymphocyte peripheral DNA, evidenced few tumor-specific single nucleotide variants in DEFB119, MUC5B, NUDT1, LTBP3 and CPSF3L genes. Differently, tumor DNA was not characterized by for the main pilocytic astrocytoma gene variations, including BRAFV600E. An inframe trinucleotides insertion involving DLX6 or lnc DLX6-AS1 genes was scored in 44.9% of sequenced reads; the temporal profile of this variation on the expression of DLX-AS1 was investigated in patient's urine-derived exosomes, reporting no significant variation in the one-year molecular follow-up. Array CGH identified a tumor microdeletion at the 6q25.3 chromosomal region, spanning 1,01 Mb and comprising ZDHHC14, SNX9, TULP4 and SYTL3 genes. The expression of these genes did not change in urine-derived exosomes during the one-year investigation period. Finally, RNAseq did not reveal any of the common pilocytic BRAF-KIAA1549 genes fusion events. CONCLUSION: To our knowledge, the present report is one of the first described gene-orphan case studies of a pediatric spinal cord pilocytic astrocytoma.

In vivo 2-hydroxyglutarate-proton magnetic resonance spectroscopy (3 T, PRESS technique) in treatment-naïve suspect lower-grade gliomas: feasibility and accuracy in a clinical setting.

Isocitrate dehydrogenase 1/2 (IDH1/2) mutations are often detected in lower-grade gliomas (LGG) and result into 2-hydroxyglutarate (2HG) synthesis. Prior studies showed that 2HG can be detected in vivo using magnetic resonance spectroscopy (MRS), but its accuracy and translational impact are still under investigation. PURPOSE: To investigate the clinical feasibility of MRS for in vivo detection and quantification of 2HG on consecutive treatment-naïve suspect LGG patients and to compare MRS accuracy with tissue IDH1/2 analysis. METHODS: MRS spectra at 3 T were acquired with 1H-MRS single-voxel PRESS 2HG-tailored sequences with TE 30 (group 1) or TE 97 (groups 2A and B). Voxel sizes were 1.5 × 1.5 × 1.5 cm3 for group 1 (n = 13) and group 2A (n = 14) and 2 × 2 × 2 cm3 for group 2B (n = 32). Multiple metabolites' concentrations were analyzed with LCModel. Tumors were assessed for IDH status and main molecular markers. 2HG levels in urine/blood were measured by liquid chromatography-mass spectrometry. RESULTS: The larger voxel TE 97 sequence resulted in highest specificity (100%), sensitivity (79%), and accuracy (87%). Urine and blood 2HG did not result predictive. CONCLUSION: Our data confirm that 2 × 2 × 2-cm3 voxel TE 97 MRS shows high accuracy for 2HG detection, with good sensitivity and 100% specificity in distinguishing IDH mutant gliomas. Main limits of the technique are small tumor volume and low cellularity. Integrating 2HG-MRS with other metabolites may help non-invasive diagnosis of glioma, prognostic assessment, and treatment planning in clinical setting.