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NF1-like optic pathway gliomas in children: clinical and molecular characterization of this specific presentation.

ABSTRACT: Background:Pediatric neurofibromatosis type 1 (NF1)-associated optic pathway gliomas (OPGs) exhibit different clinico-radiological features, treatment, and outcome compared with sporadic OPGs. While NF1-associated OPGs are caused by complete loss-of-function of the NF1 gene, other genetic alterations of the RAS-MAPK pathway are frequently described in the sporadic cases. We identified a group of patients who presented OPGs with typical radiological features of NF1-associated OPGs but without the NF1 diagnostic criteria. We aim to investigate into the possible molecular mechanisms underlying this "NF1-like" pediatric OPGs presentation. Methods:We analyzed clinico-radiological features of 16 children with NF1-like OPGs and without NF1 diagnostic criteria. We performed targeted sequencing of the NF1 gene in constitutional samples (n?=?16). The RAS-MAPK pathway major genes were sequenced in OPG tumor samples (n?=?11); BRAF FISH and IHC analyses were also performed. Results:In one patient's blood and tumor samples, we identified a NF1 nonsense mutation (exon 50: c.7285C>T, p.Arg2429*) with ~8% and ~70% VAFs, respectively, suggesting a mosaic NF1 mutation limited to the brain (segmental NF1). This patient presented signs of neurodevelopmental disorder. We identified a somatic alteration of the RAS-MAPK pathway in eight tumors: four BRAF activating p.Val600Glu mutations, three BRAF:KIAA oncogenic fusions, and one putative gain-of-function complex KRAS indel inframe mutation. Conclusions:NF1-like OPGs can rarely be associated with mosaic NF1 that needs specific constitutional DNA analyses for diagnosis. Further studies are warranted to explore unknown predisposition condition leading to the NF1-like OPG presentation, particularly in patients with the association of a neurodevelopmental disorder.

SUBMITTER: Lobon-Iglesias MJ

PROVIDER: S-EPMC7317061 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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NF1-like optic pathway gliomas in children: clinical and molecular characterization of this specific presentation.

Lobón-Iglesias María Jesús MJ Laurendeau Ingrid I Guerrini-Rousseau Léa L Tauziède-Espariat Arnault A Briand-Suleau Audrey A Varlet Pascale P Vidaud Dominique D Vidaud Michel M Brugieres Laurence L Grill Jacques J Pasmant Eric E

Neuro-oncology advances 20191220 Suppl 1

<h4>Background</h4>Pediatric neurofibromatosis type 1 (NF1)-associated optic pathway gliomas (OPGs) exhibit different clinico-radiological features, treatment, and outcome compared with sporadic OPGs. While NF1-associated OPGs are caused by complete loss-of-function of the <i>NF1</i> gene, other genetic alterations of the RAS-MAPK pathway are frequently described in the sporadic cases. We identified a group of patients who presented OPGs with typical radiological features of NF1-associated OPGs ...[more]

PMID: 32642735

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Project description:PURPOSE:An estimated 5-11% of patients with neurofibromatosis type 1 (NF1) harbour NF1 microdeletions encompassing the NF1 gene and its flanking regions. The purpose of this study was to evaluate the clinical phenotype in children and adolescents with NF1 microdeletions. METHODS:We retrospectively analysed 30 children and adolescents with NF1 microdeletions pertaining to externally visible neurofibromas. The internal tumour load was determined by volumetry of whole-body magnetic resonance imaging (MRI) in 20 children and adolescents with NF1 microdeletions. Furthermore, the prevalence of global developmental delay, autism spectrum disorder and attention deficit hyperactivity disorder (ADHD) were evaluated. RESULTS:Children and adolescents with NF1 microdeletions had significantly more often cutaneous, subcutaneous and externally visible plexiform neurofibromas than age-matched patients with intragenic NF1 mutations. Internal neurofibromas were detected in all 20 children and adolescents with NF1 microdeletions analysed by whole-body MRI. By contrast, only 17 (61%) of 28 age-matched NF1 patients without microdeletions had internal tumours. The total internal tumour load was significantly higher in NF1 microdeletion patients than in NF1 patients without microdeletions. Global developmental delay was observed in 28 (93%) of 30 children with NF1 microdeletions investigated. The mean full-scale intelligence quotient in our patient group was 77.7 which is significantly lower than that of patients with intragenic NF1 mutations. ADHD was diagnosed in 15 (88%) of 17 children and adolescents with NF1 microdeletion. Furthermore, 17 (71%) of the 24 patients investigated had T-scores ? 60 up to 75, indicative of mild to moderate autistic symptoms, which are consequently significantly more frequent in patients with NF1 microdeletions than in the general NF1 population. Also, the mean total T-score was significantly higher in patients with NF1 microdeletions than in the general NF1 population. CONCLUSION:Our findings indicate that already at a very young age, NF1 microdeletions patients frequently exhibit a severe disease manifestation which requires specialized long-term clinical care.

Project description:Unresectable hypothalamic/optic pathway pilocytic astrocytoma (PA) can be challenging to manage due to repeated progressions despite multiple lines of therapy. To identify clinical and biologic factors associated with tumor progression, we retrospectively identified 72 unresectable, non-NF1-associated, hypothalamic/optic pathway PA. Tumors were classified as low- (6.9%), intermediate- (43.1%), and high-risk (50%) based on their response to treatment. High-risk tumors were defined as those that progressed after three or more lines of chemotherapy/targeted therapy, progressed after radiation, developed metastatic disease, or died of disease. DNA methylation profiling and transcriptome analysis (RNA sequencing) were performed on treatment-naïve tumors with available tissue, and the findings were validated by immunohistochemistry (IHC) on additional tumor tissue. The median follow-up of the entire cohort was 12.3 years. High-risk tumors were associated with male sex (M:F = 2.6:1), younger age at diagnosis (median 3.2 years vs. 6.7 years, P = 0.005), and high incidence of KIAA1549-BRAF fusion (81.5% vs. 38.5%, P = 0.0032). High-risk tumors demonstrated decreased CpG methylation and increased RNA expression in many mitochondrial genes and genes downstream of E2F and NKX2.3 transcription factors. Transcriptome analysis identified transcription factor TBX3 and proto-oncogene serine/threonine protein kinase PIM1 as common downstream targets of both E2F and NKX2.3 and potential drivers of tumor progression. IHC confirmed increased expression of TBX3 and PIM1 in high-risk tumors. PIM1 is known to increase the stability and transcriptional activity of MYC, and gene enrichment analysis identified enrichment of MYC targets. Signaling pathways known to be implicated in pilocytic astrocytoma, such as MAPK and PI3K/AKT/mTOR, were also enriched, as well as pathways related to mitochondrial biogenesis and oxidative phosphorylation. Our results support the model in which the p53-PIM1-MYC axis and TBX3 act alongside MAPK and PI3K/AKT/mTOR pathways to promote tumor progression in hypothalamic/optic pathway PA, highlighting potential new targets for combination therapy and refining disease prognosis.

Dataset Information

NF1-like optic pathway gliomas in children: clinical and molecular characterization of this specific presentation.

Publications

NF1-like optic pathway gliomas in children: clinical and molecular characterization of this specific presentation.

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