NTRK2 gene fusions are uncommon in pilocytic astrocytoma.

BACKGROUND: Pilocytic astrocytoma is the most frequent pediatric glioma. Despite its overall good prognosis, complete surgical resection is sometimes unfeasible, especially for patients with deep-seated tumors. For these patients, the identification of targetable genetic alterations such as NTRK fusions, raised as a new hope for therapy. The presence of gene fusions involving NTRK2 has been rarely reported in pilocytic astrocytoma. The aim of the present study was to investigate the frequency of NTRK2 alterations in a series of Brazilian pilocytic astrocytomas. METHODS: Sixty-nine pilocytic astrocytomas, previously characterized for BRAF and FGFR1 alterations were evaluated. The analysis of NTRK2 alterations was performed using a dual color break apart fluorescence in situ hybridization (FISH) assay. RESULTS: NTRK2 fusions were successfully evaluated by FISH in 62 of the 69 cases. Neither evidence of NTRK2 gene rearrangements nor NTRK2 copy number alterations were found. CONCLUSIONS: NTRK2 alterations are uncommon genetic events in pilocytic astrocytomas, regardless of patients' clinicopathological and molecular features.

The T-box transcription factor brachyury behaves as a tumor suppressor in gliomas.

The oncogene brachyury (TBXT) is a T-box transcription factor that is overexpressed in multiple solid tumors and is associated with tumor aggressiveness and poor patient prognosis. Gliomas comprise the most common and aggressive group of brain tumors, and at the present time the functional and clinical impact of brachyury expression has not been investigated previously in these neoplasms. Brachyury expression (mRNA and protein) was assessed in normal brain (n = 67), glioma tissues (n = 716) and cell lines (n = 42), and further in silico studies were undertaken using genomic databases totaling 3115 samples. Our glioma samples were analyzed for copy number (n = 372), promoter methylation status (n = 170), and mutation status (n = 1569 tissues and n = 52 cell lines) of the brachyury gene. The prognostic impact of brachyury expression was studied in 1524 glioma patient tumors. The functional impact of brachyury on glioma proliferation, viability, and cell death was evaluated both in vitro and in vivo. Brachyury was expressed in the normal brain, and significantly downregulated in glioma tissues. Loss of brachyury was associated with tumor aggressiveness and poor survival in glioma patients. Downregulation of brachyury was not associated with gene deletion, promoter methylation, or inactivating point mutations. Brachyury re-expression in glioma cells was found to decrease glioma tumorigenesis by induction of autophagy. These data strongly suggest that brachyury behaves as a tumor suppressor gene in gliomas by modulating autophagy. It is important to note that brachyury constitutes an independent positive biomarker of patient prognosis. Our findings indicate that the role of brachyury in tumorigenesis may be tissue-dependent and demands additional investigation to guide rational interventions. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Evaluation of the prognostic potential of EGFL7 in pilocytic astrocytomas.

Pilocytic astrocytoma (PA) is the most frequent solid neoplasm in childhood. It has a good 5-year overall survival (90% in childhood and 52% in adults). However, up to 20% of patients experience residual tumor growth, recurrence, and death. Although the main genetic alteration of PAs, including KIAA1549:BRAF fusion, involves chromosome 7q34, we previously found frequent loss in chr9q34.3 locus in a small subset of these tumors. Among the genes present in this locus, EGFL7 is related to poor prognosis in several tumor types. In this study, we aimed to assess EGFL7 expression through immunohistochemistry, and to evaluate its prognostic value in a series of 64 clinically and molecularly well-characterized pilocytic astrocytomas. We found high expression of EGFL7 in 71.9% of patients. Low EGFL7 expression was associated with older patients, the mean age mainly older than 11 years (P = 0.027). EGFL7 expression was not associated with presence of KIAA1549:BRAF fusion, BRAF mutation, FGFR1 mutation, nor FGFR1 duplication. Moreover, high EGFL7 expression was associated with high FGFR1 (P = 0.037) and 5'-deoxy-5'-methyltioadenosine phosphorylase (MTAP) (P = 0.005) expression, and with unfavorable outcome of patients (P = 0.047). Multivariate analysis revealed low EGFL7 expression related to older patients and high EGFL7 expression related to retained expression of MTAP. In addition, we found a borderline significance of unfavorable outcome and high EGFL7 expression. Finally, EGFL7 expression was not associated with overall or event-free survival of PA patients. Our findings point to EGFL7 expression as a novel candidate prognostic marker in PA, which should be further investigated.

Study of hTERT and Histone 3 Mutations in Medulloblastoma.

Hotspot activating mutations of the telomerase reverse transcriptase (hTERT) promoter region were recently described in several tumor types. These mutations lead to enhanced expression of telomerase, being responsible for telomere maintenance and allowing continuous cell division. Additionally, there are alternative telomere maintenance mechanisms, associated with histone H3 mutations, responsible for disrupting the histone code and affecting the regulation of transcription. Here, we investigated the clinical relevance of these mechanistically related molecules in medulloblastoma. Sixty-nine medulloblastomas, formalin fixed and paraffin embedded, from a cohort of patients aged 1.5-70 years, were used to investigate the hotspot mutations of the hTERT promoter region, i.e. H3F3A and HIST1H3B, using Sanger sequencing. We successfully sequenced hTERT in all 69 medulloblastoma samples and identified a total of 19 mutated cases (27.5%). c.-124:G>A and c.-146:G>A mutations were detected, respectively, in 16 and 3 samples. Similar to previous reports, hTERT mutations were more frequent in older patients (p < 0.0001), being found only in 5 patients <20 years of age. In addition, hTERT-mutated tumors were more frequently recurrent (p = 0.026) and hTERT mutations were significantly enriched in tumors located in the right cerebellar hemisphere (p = 0.039). No mutations were found on the H3F3A or HIST1H3B genes. hTERT promoter mutations are frequent in medulloblastoma and are associated with older patients, prone to recurrence and located in the right cerebellar hemisphere. On the other hand, histone 3 mutations do not seem to be present in medulloblastoma.

The prognostic impact of TERT promoter mutations in glioblastomas is modified by the rs2853669 single nucleotide polymorphism.

Human hotspot TERT promoter (TERTp) mutations have been reported in a wide range of tumours. Several studies have shown that TERTp mutations are associated with clinicopathological features; in some instances, TERTp mutations were considered as biomarkers of poor prognosis. The rs2853669 SNP, located in the TERT promoter region, was reported to modulate the increased TERT expression levels induced by the recurrent somatic mutations. In this study we aimed to determine the frequency and prognostic value of TERTp mutations and TERT rs2853669 SNP in 504 gliomas from Portuguese and Brazilian patients. TERTp mutations were detected in 47.8% of gliomas (216/452). Glioblastomas (GBM) exhibited the highest frequency of TERTp mutations (66.9%); in this glioma subtype, we found a significant association between TERTp mutations and poor prognosis, regardless of the population. Moreover, in a multivariate analysis, TERTp mutations were the only independent prognostic factor. Our data also showed that the poor prognosis conferred by TERTp mutations was restricted to GBM patients carrying the rs2853669 A allele and not in those carrying the G allele. In conclusion, the presence of TERTp mutations was associated with worse prognosis in GBM patients, although such association depended on the status of the rs2853669 SNP. The status of the rs2853669 SNP should be taken in consideration when assessing the prognostic value of TERTp mutations in GBM patients. TERTp mutations and the rs2853669 SNP can be used in the future as biomarkers of glioma prognosis.

Expression of Methylthioadenosine Phosphorylase (MTAP) in Pilocytic Astrocytomas.

BACKGROUND/OBJECTIVES: Pilocytic astrocytomas (PAs) are the most frequent astrocytomas in children and adolescents. Methilthioadenosine phosphorylase(MTAP) is a tumor-suppressor gene, the loss of expression of which is associated with a poor prognosis and better response to specific chemotherapy in leukemia and non-small-cell lung cancer. The expression of MTAP in brain tumors remains largely unknown and its biological role in PA is still unexplored. Our aims were to describe the immunohistochemical MTAP expression in a series of PAs and relate it to the clinicopathological features of the patients. METHODS: We assessed MTAP expression on immunohistochemistry in 69 pediatric and adult patients with PA in a tissue microarray platform. RESULTS: Retained expression of MTAP was seen in >85% of the tumors compared to in the nonneoplastic adjacent tissue. Only 3 supratentorial tumors showed a complete loss of MTAP expression. No significant association with clinicopathological features or overall survival of the patients was found. CONCLUSIONS: MTAP expression is retained in PAs and is not an outcome predictor for these tumors. Nevertheless, a subset of patients with PAs exhibiting a loss of MTAP could potentially benefit from treatment with specific chemotherapy, especially when lesions are recurrent or surgical resection is not recommended.

Angiogenesis and expression of PDGF-C, VEGF, CD105 and HIF-1α in human glioblastoma.

Glioblastoma (GBM), the most frequent and aggressive brain tumor, is characterized by marked angiogenesis directly related to invasiveness and poor prognosis. Hypoxia is considered to be an important stimulus for angiogenesis by inducing hypoxia-inducible factor 1-alpha (HIF-1α) overexpression that activates platelet-derived growth factor (PDGF) and VEGF. The aim of this study is to analyze the expression of PDGF-C, VEGF in endothelial and tumor cells of GBM and their relation to HIF-1α expression. Two hundred and eight GBM cases were studied by tissue microarray immunohistochemical preparation. Expression of HIF-1α, VEGF and PDGF-C was observed in 184 (88.5%), 131 (63%) and 160 (76.9%) tumor cases, respectively. The numbers of vessels were quantified by CD34, PDGF-C, VEGF and CD105 staining, and were in median 20, 16, 5 and 6, respectively. The GBMs that showed positive or negative expression for HIF-1α showed a median vascular density of 30 and 14, respectively, for CD34 (P < 0.015). Positive expression for HIF-1α was correlated with VEGF and PDGF-C expression in tumors (P < 0.001). There was a significant correlation between VEGF and PDGF-C expression in the cytoplasm of GBM tumor cells (P < 0.0001). We showed that VEGF expression in tumor cells was correlated with its expression in blood vessels (P < 0.0001). Endothelial cells with PDGF-C and VEGF positive expression were also positive for CD105 and their nuclei for Ki-67, confirming the neoangiogenic and proliferative influence of VEGF and PDGF-C. VEGF nuclear staining in tumor cells (P = 0.002) as well as nuclear staining for HIF-1α and VEGF (P = 0.005) correlated with survival. In summary, our present findings of the concomitant upregulation of PDGF-C with VEGF in GBM tumor cells and vessels further reinforce the benefit of using combined anti-angiogenic approaches to potentially improve the therapeutic response for GBM.

Incidence of venous thromboembolism and bleeding in patients with malignant central nervous system neoplasm: Systematic review and meta-analysis.

Central nervous system (CNS) malignant neoplasms may lead to venous thromboembolism (VTE) and bleeding, which result in rehospitalization, morbidity and mortality. We aimed to assess the incidence of VTE and bleeding in this population. METHODS: This systematic review and meta-analysis (PROSPERO CRD42023423949) were based on a standardized search of PubMed, Virtual Health Library and Cochrane (n = 1653) in July 2023. After duplicate removal, data screening and collection were conducted by independent reviewers. The combined rates and 95% confidence intervals for the incidence of VTE and bleeding were calculated using the random effects model with double arcsine transformation. Subgroup analyses were performed based on sex, age, income, and type of tumor. Heterogeneity was calculated using Cochran's Q test and I2 statistics. Egger's test and funnel graphs were used to assess publication bias. RESULTS: Only 36 studies were included, mainly retrospective cohorts (n = 30, 83.3%) from North America (n = 20). Most studies included were published in high-income countries. The sample size of studies varied between 34 and 21,384 adult patients, mostly based on gliomas (n = 30,045). For overall malignant primary CNS neoplasm, the pooled incidence was 13.68% (95%CI 9.79; 18.79) and 11.60% (95%CI 6.16; 18.41) for VTE and bleeding, respectively. The subgroup with elderly people aged 60 or over had the highest incidence of VTE (32.27% - 95%CI 14.40;53.31). The studies presented few biases, being mostly high quality. Despite some variability among the studies, we observed consistent results by performing sensitivity analysis, which highlight the robustness of our findings. CONCLUSIONS: Our study showed variability in the pooled incidence for both overall events and subgroup analyses. It was highlighted that individuals over 60 years old or diagnosed with GBM had a higher pooled incidence of VTE among those with overall CNS malignancies. It is important to note that the results of this meta-analysis refer mainly to studies carried out in high-income countries. This highlights the need for additional research in Latin America, and low- and middle-income countries.

EGFL7 expression profile in IDH-wildtype glioblastomas is associated with poor patient outcome.

BACKGROUND: Despite the advances in glioblastoma (GBM) treatment, the average life span of patients is 14 months. Therefore, it is urgent to identity biomarkers of prognosis, treatment response, or development of novel treatment strategies. We previously described the association of high epidermal growth factor-like domain multiple 7 (EGFL7) expression and unfavorable outcome of pilocytic astrocytoma patients. The present study aims to analyze the prognostic potential of EGFL7 in GBM isocitrate dehydrogenase (IDH)-wildtype, using immunohistochemistry and in silico approaches. METHODS: Spearman's correlation analysis of The Cancer Genome Atlas RNA sequencing data was performed. The genes strongly correlated to EGFL7 expression were submitted to enrichment gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Additionally, EGFL7 expression was associated with patient overall survival. The expression of EGFL7 was analyzed through immunohistochemistry in 74 GBM IDH-wildtype patients' samples, and was associated with clinicopathological data and overall survival. RESULTS: In silico analysis found 78 genes strongly correlated to EGFL7 expression. These genes were enriched in 40 biological processes and eight KEGG pathways, including angiogenesis/vasculogenesis, cell adhesion, and phosphoinositide 3-kinase-Akt, Notch, and Rap1 signaling pathways. The immunostaining showed high EGFL7 expression in 39 cases (52.7%). High immunolabelling was significantly associated with low Karnofsky Performance Status and poor overall survival. Cox analysis showed that GBMs IDH-wildtype with high EGFL7 expression presented a higher risk of death compared to low expression (hazard ratio, 1.645; 95% confidence interval, 1.021 to 2.650; p = .041). CONCLUSIONS: This study gives insights regarding the genes that are correlated with EGFL7, as well as biological processes and signaling pathways, which should be further investigated in order to elucidate their role in glioblastoma biology.

Loss of 5'-Methylthioadenosine Phosphorylase (MTAP) is Frequent in High-Grade Gliomas; Nevertheless, it is Not Associated with Higher Tumor Aggressiveness.

The 5'-methylthioadenosine phosphorylase (MTAP) gene is located in the chromosomal region 9p21. MTAP deletion is a frequent event in a wide variety of human cancers; however, its biological role in tumorigenesis remains unclear. The purpose of this study was to characterize the MTAP expression profile in a series of gliomas and to associate it with patients' clinicopathological features. Moreover, we sought to evaluate, through glioma gene-edited cell lines, the biological impact of MTAP in gliomas. MTAP expression was evaluated in 507 glioma patients by immunohistochemistry (IHC), and the expression levels were associated with patients' clinicopathological features. Furthermore, an in silico study was undertaken using genomic databases totalizing 350 samples. In glioma cell lines, MTAP was edited, and following MTAP overexpression and knockout (KO), a transcriptome analysis was performed by NanoString Pan-Cancer Pathways panel. Moreover, MTAP's role in glioma cell proliferation, migration, and invasion was evaluated. Homozygous deletion of 9p21 locus was associated with a reduction of MTAP mRNA expression in the TCGA (The Cancer Genome Atlas) - glioblastoma dataset (p < 0.01). In addition, the loss of MTAP expression was markedly high in high-grade gliomas (46.6% of cases) determined by IHC and Western blotting (40% of evaluated cell lines). Reduced MTAP expression was associated with a better prognostic in the adult glioblastoma dataset (p < 0.001). Nine genes associated with five pathways were differentially expressed in MTAP-knockout (KO) cells, with six upregulated and three downregulated in MTAP. Analysis of cell proliferation, migration, and invasion did not show any significant differences between MTAP gene-edited and control cells. Our results integrating data from patients as well as in silico and in vitro models provide evidence towards the lack of strong biological importance of MTAP in gliomas. Despite the frequent loss of MTAP, it seems not to have a clinical impact in survival and does not act as a canonic tumor suppressor gene in gliomas.

Association study of an epidermal growth factor gene functional polymorphism with the risk and prognosis of gliomas in Brazil.

Epidermal growth factor (EGF) plays an important role in cancer. A functional single nucleotide polymorphism (SNP) in the 5'-untranslated region of the EGF gene (+61 A>G) may influence its expression and contribute to cancer predisposition and aggressiveness. Aiming to investigate the role of EGF +61 A>G in the susceptibility to glioma and its prognosis, we performed a case-control study with 165 patients and 200 healthy controls from Brazil. Comparisons of genotype distributions and allele frequencies did not reveal any significant differences between the groups. The mean overall survival was 9.2 months for A/A, 8.2 months for A/G, and 7.7 months for G/G. When survival curves were plotted we found that the +61G allele is associated with poor overall survival (p=0.023) but not with disease-free survival (p=0.527). Our data suggest that, although there is no association between the EGF +61 A>G genotype and glioma susceptibility, this SNP is associated with shorter overall survival of glioma patients in the Brazilian population. Nevertheless, future studies utilizing a larger series are essential for a definitive conclusion.

OTX1 and OTX2 Genes in Medulloblastoma.

OBJECTIVE: To study the prevalence of OTX1 and OTX2 gene expression in 60 medulloblastoma specimen samples and to establish correlations between gene expression and clinical and histopathological aspects. METHODS: We performed a retrospective analysis of 60 patients with a diagnosis of medulloblastoma at the Clinicas Hospital of the School of Medicine, University of São Paulo, and the Cancer Hospital of Barretos. We created a database of the 60 patients containing information on the gene expression of OTX1 and OTX2 (obtained using real-time polymerase chain reaction) and clinical and epidemiological data. Statistical tests were performed to verify potential correlations of clinicopathological data and follow-up aspects with gene expression. RESULTS: The OTX1 gene was expressed in 52% of the study population. Expression varied with age (higher in adults), location (predominantly by hemisphere), and histological type (desmoplastic). The OTX2 gene was expressed in 62% of the study population. Expression varied with age (higher in younger age groups), location (predominantly vermis), and histological type (classic and anaplastic). A statistical correlation between OTX2 gene expression and the development of leptomeningeal metastases was observed. CONCLUSIONS: The relative expression of OTX1 and OTX2 was dependent on patient age, tumor location, and histological variant. In addition, OTX2 expression might be a predictive factor for leptomeningeal metastases of medulloblastoma. The OTX pathway should be consider as an important venue for medulloblastomas development.

WNT6 is a novel oncogenic prognostic biomarker in human glioblastoma.

Glioblastoma (GBM) is a universally fatal brain cancer, for which novel therapies targeting specific underlying oncogenic events are urgently needed. While the WNT pathway has been shown to be frequently activated in GBM, constituting a potential therapeutic target, the relevance of WNT6, an activator of this pathway, remains unknown. Methods: WNT6 protein and mRNA levels were evaluated in GBM. WNT6 levels were silenced or overexpressed in GBM cells to assess functional effects in vitro and in vivo. Phospho-kinase arrays and TCF/LEF reporter assays were used to identify WNT6-signaling pathways, and significant associations with stem cell features and cancer-related pathways were validated in patients. Survival analyses were performed with Cox regression and Log-rank tests. Meta-analyses were used to calculate the estimated pooled effect. Results: We show that WNT6 is significantly overexpressed in GBMs, as compared to lower-grade gliomas and normal brain, at mRNA and protein levels. Functionally, WNT6 increases typical oncogenic activities in GBM cells, including viability, proliferation, glioma stem cell capacity, invasion, migration, and resistance to temozolomide chemotherapy. Concordantly, in in vivo orthotopic GBM mice models, using both overexpressing and silencing models, WNT6 expression was associated with shorter overall survival, and increased features of tumor aggressiveness. Mechanistically, WNT6 contributes to activate typical oncogenic pathways, including Src and STAT, which intertwined with the WNT pathway may be critical effectors of WNT6-associated aggressiveness in GBM. Clinically, we establish WNT6 as an independent prognostic biomarker of shorter survival in GBM patients from several independent cohorts. Conclusion: Our findings establish WNT6 as a novel oncogene in GBM, opening opportunities to develop more rational therapies to treat this highly aggressive tumor.

Copy Number Profiling of Brazilian Astrocytomas.

Copy number alterations (CNA) are one of the driving mechanisms of glioma tumorigenesis, and are currently used as important biomarkers in the routine setting. Therefore, we performed CNA profiling of 65 astrocytomas of distinct malignant grades (WHO grade I-IV) of Brazilian origin, using array-CGH and microsatellite instability analysis (MSI), and investigated their correlation with TERT and IDH1 mutational status and clinico-pathological features. Furthermore, in silico analysis using the Oncomine database was performed to validate our findings and extend the findings to gene expression level. We found that the number of genomic alterations increases in accordance with glioma grade. In glioblastomas (GBM), the most common alterations were gene amplifications (PDGFRA, KIT, KDR, EGFR, and MET) and deletions (CDKN2A and PTEN) Log-rank analysis correlated EGFR amplification and/or chr7 gain with better survival of the patients. MSI was observed in 11% of GBMs. A total of 69% of GBMs presented TERT mutation, whereas IDH1 mutation was most frequent in diffuse (85.7%) and anaplastic (100%) astrocytomas. The combination of 1p19q deletion and TERT and IDH1 mutational status separated tumor groups that showed distinct age of diagnosis and outcome. In silico validation pointed to less explored genes that may be worthy of future investigation, such as CDK2, DMRTA1, and MTAP Herein, using an extensive integrated analysis, we indicated potentially important genes, not extensively studied in gliomas, that could be further explored to assess their biological and clinical impact in astrocytomas.

CXCR7 and CXCR4 Expressions in Infiltrative Astrocytomas and Their Interactions with HIF1α Expression and IDH1 Mutation.

The CXCR7, a new receptor for CXCL12 with higher affinity than CXCR4 has raised key issues on glioma cell migration. The aim of this study is to investigate the CXCR7 mRNA expression in diffuse astrocytomas tissues and to evaluate its interactions with CXCR4 and HIF1α expression and IDH1 mutation. CXCR7, CXCR4 and HIF1α mRNA expression were evaluated in 129 frozen samples of astrocytomas. IDH1 mutation status was analyzed with gene expressions, matched with clinicopathological parameters and overall survival time. Protein expression was analyzed by immunohistochemistry in different grades of astrocytoma and in glioma cell line (U87MG) by confocal microscopy. There was significant difference in the expression levels of the genes studied between astrocytomas and non-neoplasic (NN) controls (p < 0.001). AGII showed no significant correlation between CXCR7/HIF1α (p = 0.548); there was significant correlation between CXCR7/CXCR4 (p = 0.042) and CXCR7/IDH1 (p = 0.008). GBM showed significant correlations between CXCR7/CXCR4 (p = 0.002), CXCR7/IDH1 (p < 0.001) and CXCR7/HIF1α (p = 0.008). HIF1α overexpression was associated with higher expressions of CXCR7 (p = 0.01) and CXCR4 (p < 0.0001), while IDH1 mutation was associated with lower CXCR7 (p = 0.009) and CXCR4 (p = 0.0005) mRNA expressions. Protein expression increased with malignancy and in U87MG cell line was mainly localized in the cellular membrane. CXCR7 was overexpressed in astrocytoma and correlates with CXCR4 and IDH1 in AGII and CXCR4, IDH1 and HIF1α in GBM. Overexpression HIF1α was related with higher expressions of CXCR7 and CXCR4, otherwise IDH1 mutation related with lower expression of both genes. No association between CXCR7 and CXCR4 expression and survival data was related.

Meningioma of the Fourth Ventricle: Literature Review

Meningiomas are among the most common central nervous system tumors, with an incidence that ranges from 15% to 40% of intracranial tumors. Of these, only 0.5% to 3% are intraventricular, and the rarest of them occurs in the fourth ventricle. Fourth-ventricle meningiomas originate generally fromthe choroid plexus and have no dural adhesions. Most often, they manifest in young patients, around 41 years of age, with a possible predominance in females, through intracranial hypertension and cerebellar syndromes. The treatment consists of surgical resection, which commonly presents good results due to the characteristics of the tumor. So, for better preoperative planning, the radiological differentiation of the most frequent tumors in this location is important. Themost common histologic subtypes are fibroblastic and meningothelial, both grade I according to the World Health Organization (WHO), although there are reports of tumors of grades II and III. We report a case ofmeningioma of the fourth ventricle operated in our institution, and we have conducted a literature review, through which we found that 57 cases have been reported so far, with the first one reported in 1938.

KIAA1549: BRAF Gene Fusion and FGFR1 Hotspot Mutations Are Prognostic Factors in Pilocytic Astrocytomas.

Up to 20% of patients with pilocytic astrocytoma (PA) experience a poor outcome. BRAF alterations and Fibroblast growth factor receptor 1 (FGFR1) point mutations are key molecular alterations in Pas, but their clinical implications are not established. We aimed to determine the frequency and prognostic role of these alterations in a cohort of 69 patients with PAs. We assessed KIAA1549:BRAF fusion by fluorescence in situ hybridization and BRAF (exon 15) mutations by capillary sequencing. In addition, FGFR1 expression was analyzed using immunohistochemistry, and this was compared with gene amplification and hotspot mutations (exons 12 and 14) assessed by fluorescence in situ hybridization and capillary sequencing. KIAA1549:BRAF fusion was identified in almost 60% of cases. Two tumors harbored mutated BRAF. Despite high FGFR1 expression overall, no cases had FGFR1 amplifications. Three cases harbored a FGFR1 p.K656E point mutation. No correlation was observed between BRAF and FGFR1 alterations. The cases were predominantly pediatric (87%), and no statistical differences were observed in molecular alterations-related patient ages. In summary, we confirmed the high frequency of KIAA1549:BRAF fusion in PAs and its association with a better outcome. Oncogenic mutations of FGFR1, although rare, occurred in a subset of patients with worse outcome. These molecular alterations may constitute alternative targets for novel clinical approaches, when radical surgical resection is unachievable.

Molecular Profiling of a Rare Rosette-Forming Glioneuronal Tumor Arising in the Spinal Cord.

Rosette-forming glioneuronal tumor (RGNT) of the IV ventricle is a rare and recently recognized brain tumor entity. It is histologically composed by two distinct features: a glial component, resembling pilocytic astrocytoma, and a component forming neurocytic rosettes and/or perivascular rosettes. Herein, we describe a 33-year-old man with RGNT arising in the spinal cord. Following an immunohistochemistry validation, we further performed an extensive genomic analysis, using array-CGH (aCGH), whole exome and cancer-related hotspot sequencing, in order to better understand its underlying biology. We observed the loss of 1p and gain of 1q, as well as gain of the whole chromosomes 7, 9 and 16. Local amplifications in 9q34.2 and 19p13.3 (encompassing the gene SBNO2) were identified. Moreover, we observed focal gains/losses in several chromosomes. Additionally, on chromosome 7, we identified the presence of the KIAA1549:BRAF gene fusion, which was further validated by RT-PCR and FISH. Across all mutational analyses, we detected and validated the somatic mutations of the genes MLL2, CNNM3, PCDHGC4 and SCN1A. Our comprehensive molecular profiling of this RGNT suggests that MAPK pathway and methylome changes, driven by KIAA1549:BRAF fusion and MLL2 mutation, respectively, could be associated with the development of this rare tumor entity.

In Vitro and In Vivo Analysis of RTK Inhibitor Efficacy and Identification of Its Novel Targets in Glioblastomas.

Treatment for glioblastoma consists of radiotherapy and temozolomide-based chemotherapy. However, virtually all patients recur, leading to a fatal outcome. Receptor tyrosine kinase (RTK)-targeted therapy has been the focus of attention in novel treatment options for these patients. Here, we compared the efficacy of imatinib, sunitinib, and cediranib in glioblastoma models. In the present work, the biologic effect of the drugs was screened by viability, cell cycle, apoptosis, migration, and invasion in vitro assays or in vivo by chick chorioallantoic membrane assay. Intracellular signaling was assessed by Western blot and the RTK targets were identified using phospho-RTK arrays. The amplified status of KIT, PDGFRA, and VEGFR2 genes was assessed by quantitative polymerase chain reaction. In a panel of 10 glioblastoma cell lines, we showed that cediranib was the most potent. In addition, cediranib and sunitinib synergistically sensitize the cells to temozolomide. Cediranib efficacy was shown to associate with higher cytostatic and unique cytotoxic effects in vitro and both antitumoral and antiangiogenic activity in vivo, which could associate with its great capacity to inhibit mitogen-activated protein kinase (MAPK) and AKT pathways. The molecular status of KIT, PDGFRA, and VEGFR2 did not predict glioblastoma cell responsiveness to any of the RTK inhibitors. Importantly, phospho-RTK arrays revealed novel targets for cediranib and sunitinib therapy. In conclusion, the novel targets found may be of value as future biomarkers for therapy response in glioblastoma and lead to the rational selection of patients for effective molecular targeted treatment.