Abstract
BACKGROUND
Approximately 20% of low-grade gliomas (LGG) display visible protoporphyrin fluorescence during surgery after 5-aminolevulinic acid (5-ALA) administration.
OBJECTIVE
To determine ...if fluorescence represents a prognostic marker in LGG.
METHODS
Seventy-four consecutive patients with LGG (World Health Organization 2016) were operated on with 5-ALA. Fluorescent tissue was specifically biopsied. Tumor size, age, Karnofsky index, contrast-enhancement, fluorescence, and molecular factors (IDH1/IDH2-mutations, Ki67/MIB1 Index, 1p19q codeletions, ATRX, EGFR, p53 expression, and O6-methylguanine DNA methyltransferase promotor methylation), were related to progression-free survival (PFS), malignant transformation-free survival (MTFS) and overall survival (OS).
RESULTS
Sixteen of seventy-four LGGs (21.6%) fluoresced. Fluorescence was partially related to weak enhancement on magnetic resonance imaging and increased (positron emission tomography)PET-FET uptake, but not to Karnofsky Performance Score, tumor size, or age. Regarding molecular markers, only EGFR expression differed marginally (fluorescing vs nonfluorescing: 19% vs 5%; P = .057). Median follow-up was 46.4 mo (95% confidence interval CI: 41.8-51.1). PFS, MTFS, and OS were shorter in fluorescing tumors (PFS: median 9.8 mo, 95% CI: 1.00-27.7 vs 45.8, 31.9-59.7, MTFS: 43.0 27.5-58.5 vs 64.6 57.7-71.5, median not reached, P = .015; OS: 51.6, 34.8-68.3 vs 68.2, 62.7-73.8, P = .002). IDH mutations significantly predicted PFS, MTFS, and OS. In multivariate analysis IDH status and fluorescence both independently predicted MTFS and OS. PFS was not independently predicted by fluorescence.
CONCLUSION
This is the first report investigating the role of ALA-induced fluorescence in histologically confirmed LGG. Fluorescence appeared to be a marker for inherent malignant transformation and OS, independently of known prognostic markers. Fluorescence in LGG might be taken into account when deciding on adjuvant therapies.
Missense mutations of the V600E type constitute the vast majority of tumor-associated somatic alterations in the v-RAF murine sarcoma viral oncogene homolog B1 (
BRAF
) gene. Initially described in ...melanoma, colon and papillary thyroid carcinoma, these alterations have also been observed in primary nervous system tumors albeit at a low frequency. We analyzed exon 15 of
BRAF
spanning the V600 locus by direct sequencing in 1,320 adult and pediatric tumors of the nervous system including various types of glial, embryonal, neuronal and glioneuronal, meningeal, adenohypophyseal/sellar, and peripheral nervous system tumors. A total of 96
BRAF
mutations were detected; 93 of the V600E type and 3 cases with a three base pair insertion between codons 599 and 600. The highest frequencies of
BRAF
V600E
mutations were found in WHO grade II pleomorphic xanthoastrocytomas (42/64; 66%) and pleomorphic xanthoastrocytomas with anaplasia (15/23; 65%), as well as WHO grade I gangliogliomas (14/77; 18%), WHO grade III anaplastic gangliogliomas (3/6) and pilocytic astrocytomas (9/97; 9%). In pilocytic astrocytomas
BRAF
V600E
mutation was strongly associated with extra-cerebellar location (
p
= 0.009) and was most frequent in diencephalic tumors (4/12; 33%). Glioblastomas and other gliomas were characterized by a low frequency or absence of mutations. No mutations were detected in non-glial tumors, including embryonal tumors, meningiomas, nerve sheath tumors and pituitary adenomas. The high mutation frequencies in pleomorphic xanthoastrocytomas, gangliogliomas and extra-cerebellar pilocytic astrocytomas implicate
BRAF
V600E
mutation as a valuable diagnostic marker for these rare tumor entities. Future clinical trials should address whether
BRAF
V600E
mutant brain tumor patients will benefit from
BRAF
V600E
-directed targeted therapies.
Abstract
Atypical teratoid rhabdoid tumor (ATRT) is a rare, highly malignant central nervous system cancer arising in infants and younger children, historically considered to be homogeneous, ...monogenic, and incurable. Recent use of intensified therapies has modestly improved survival for ATRT; however, a majority of patients will still succumb to their disease. While ATRTs almost universally exhibit loss of SMARCB1 (BAF47/INI1/SNF5), recent whole genome, transcriptome, and epigenomic analyses of large cohorts reveal previously underappreciated molecular heterogeneity. These discoveries provide novel insights into how SMARCB1 loss drives oncogenesis and confer specific therapeutic vulnerabilities, raising exciting prospects for molecularly stratified treatment for patients with ATRT.
Abstract
The histological and molecular features and even the mere existence of diffuse astrocytoma, IDH-wildtype, remain unclear. We therefore examined 212 diffuse astrocytomas (grade II WHO) in ...adults using IDH1(R132H) immunohistochemistry followed by IDH1/IDH2 sequencing and neuroimaging review. DNA methylation status and copy number profiles were assessed by Infinium HumanMethylation450k BeadChip. Only 25/212 patients harbored tumors without IDH1/IDH2 hotspot mutations and without contrast enhancement. By DNA methylation profiling, 10/25 tumors were classified as glioblastoma, IDH-wildtype, and an additional 7 cases could not be classified using methylome analysis, but showed genetic characteristics of glioblastoma. Histologically, all of these 17 tumors were low-grade diffuse astrocytomas. Nevertheless, 10/17 patients experienced early malignant progression. Other methylation classes included diffuse midline glioma, H3 K27M-mutant, diffuse astrocytoma, IDH-mutant, pilocytic astrocytoma, and normal or reactive brain tissue (total n = 8). In conclusion, no convincing diffuse astrocytoma, IDH-wildtype, was identified. Most IDH-wildtype tumors showing histopathological and radiological features of low-grade diffuse astrocytoma exhibit molecular and clinical features of high-grade glioma and may represent an early stage of primary glioblastoma. Our findings have implications for the biology, classification and neuropathological diagnosis of diffuse astrocytoma, IDH-wildtype in adults.
Abstract
Background
Controversy exists as to what may be defined as standard of care (including markers for stratification) for patients with atypical teratoid/rhabdoid tumors (ATRTs). The European ...Rhabdoid Registry (EU-RHAB) recruits uniformly treated patients and offers standardized genetic and DNA methylation analyses.
Methods
Clinical, genetic, and treatment data of 143 patients from 13 European countries were analyzed (2009–2017). Therapy consisted of surgery, anthracycline-based induction, and either radiotherapy or high dose chemotherapy following a consensus among European experts. Fluorescence in situ hybridization, multiplex ligation-dependent probe amplification, and sequencing were employed for assessment of somatic and germline mutations in SWItch/sucrose nonfermentable related, matrix associated, actin dependent regulator of chromatin, subfamily B (SMARCB1). Molecular subgroups (ATRT-SHH, ATRT-TYR, and ATRT-MYC) were determined using DNA methylation arrays, resulting in profiles of 84 tumors.
Results
Median age at diagnosis of 67 girls and 76 boys was 29.5 months. Five-year overall survival (OS) and event-free survival (EFS) were 34.7 ± 4.5% and 30.5 ± 4.2%, respectively. Tumors displayed allelic partial/whole gene deletions (66%; 122/186 alleles) or single nucleotide variants (34%; 64/186 alleles) of SMARCB1. Germline mutations were detected in 26% of ATRTs (30/117). The patient cohort consisted of 47% ATRT-SHH (39/84), 33% ATRT-TYR (28/84), and 20% ATRT-MYC (17/84). Age <1 year, non-TYR signature (ATRT-SHH or -MYC), metastatic or synchronous tumors, germline mutation, incomplete remission, and omission of radiotherapy were negative prognostic factors in univariate analyses (P < 0.05). An adjusted multivariate model identified age <1 year and a non-TYR signature as independent negative predictors of OS: high risk (<1 y + non-TYR; 5-y OS = 0%), intermediate risk (<1 y + ATRT-TYR or ≥1 y + non-TYR; 5-y OS = 32.5 ± 8.7%), and standard risk (≥1 y + ATRT-TYR, 5-y OS = 71.5 ± 12.2%).
Conclusions
Age and molecular subgroup status are independent risk factors for survival in children with ATRT. Our model warrants validation within future clinical trials.
Medulloblastoma is the most common pediatric malignant brain tumor. Although current therapies improve survival, these regimens are highly toxic and are associated with significant morbidity. Here, ...we report that placental growth factor (PlGF) is expressed in the majority of medulloblastomas, independent of their subtype. Moreover, high expression of PlGF receptor neuropilin 1 (Nrp1) correlates with poor overall survival in patients. We demonstrate that PlGF and Nrp1 are required for the growth and spread of medulloblastoma: PlGF/Nrp1 blockade results in direct antitumor effects in vivo, resulting in medulloblastoma regression, decreased metastasis, and increased mouse survival. We reveal that PlGF is produced in the cerebellar stroma via tumor-derived Sonic hedgehog (Shh) and show that PlGF acts through Nrp1—and not vascular endothelial growth factor receptor 1—to promote tumor cell survival. This critical tumor-stroma interaction—mediated by Shh, PlGF, and Nrp1 across medulloblastoma subtypes—supports the development of therapies targeting PlGF/Nrp1 pathway.
Display omitted
► PlGF is expressed in medulloblastomas, regardless of their genetic subtype ► The majority of PlGF protein is secreted by cerebellar stromal cells ► Stromal PlGF production is stimulated by paracrine Shh secretion from cancer cells ► Targeting PlGF/Nrp1 pathway suppresses growth and spread of medulloblastoma
Placental growth factor (PlGF) and its receptor neuropilin 1 are required for the growth of medulloblastoma, the most common malignant brain tumor in children. Experiments in mice suggest that inhibition of PlGF or neuropilin may be an effective therapeutic strategy for suppressing the growth of these tumors.
Dysembryoplastic neuroepithelial tumor (DNET) is a benign brain tumor associated with intractable drug-resistant epilepsy. In order to identify underlying genetic alterations and molecular ...mechanisms, we examined three family members affected by multinodular DNETs as well as 100 sporadic tumors from 96 patients, which had been referred to us as DNETs. We performed whole-exome sequencing on 46 tumors and targeted sequencing for hotspot
FGFR1
mutations and BRAF p.V600E was used on the remaining samples. FISH, copy number variation assays and Sanger sequencing were used to validate the findings. By whole-exome sequencing of the familial cases, we identified a novel germline
FGFR1
mutation, p.R661P. Somatic activating
FGFR1
mutations (p.N546K or p.K656E) were observed in the tumor samples and further evidence for functional relevance was obtained by in silico modeling. The FGFR1 p.K656E mutation was confirmed to be
in cis
with the germline p.R661P variant. In 43 sporadic cases, in which the diagnosis of DNET could be confirmed on central blinded neuropathology review, FGFR1 alterations were also frequent and mainly comprised intragenic tyrosine kinase
FGFR1
duplication and multiple mutants
in cis
(25/43; 58.1 %) while BRAF p.V600E alterations were absent (0/43). In contrast, in 53 cases, in which the diagnosis of DNET was not confirmed,
FGFR1
alterations were less common (10/53; 19 %;
p
< 0.0001) and hotspot BRAF p.V600E (12/53; 22.6 %) (
p
< 0.001) prevailed. We observed overexpression of phospho-ERK in FGFR1 p.R661P and p.N546K mutant expressing HEK293 cells as well as
FGFR1
mutated tumor samples, supporting enhanced MAP kinase pathway activation under these conditions. In conclusion, constitutional and somatic
FGFR1
alterations and MAP kinase pathway activation are key events in the pathogenesis of DNET. These findings point the way towards existing targeted therapies.
Biallelic inactivation of SMARCB1, encoding a member of the SWI/SNF chromatin remodeling complex, is the hallmark genetic aberration of atypical teratoid rhabdoid tumors (ATRT). Here, we report how ...loss of SMARCB1 affects the epigenome in these tumors. Using chromatin immunoprecipitation sequencing (ChIP-seq) on primary tumors for a series of active and repressive histone marks, we identified the chromatin states differentially represented in ATRTs compared with other brain tumors and non-neoplastic brain. Re-expression of SMARCB1 in ATRT cell lines enabled confirmation of our genome-wide findings for the chromatin states. Additional generation of ChIP-seq data for SWI/SNF and Polycomb group proteins and the transcriptional repressor protein REST determined differential dependencies of SWI/SNF and Polycomb complexes in regulation of diverse gene sets in ATRTs.
•ATRT epigenomes display a global depletion of H3K27ac and H3K27me3•Neuronal genes bound by SMARCB1 in normal brain are repressed by EZH2 in ATRT•ATRT harbor many active genes occupied by EZH2 but without occupancy of H3K27me3•Residual SWI/SNF occupancy maintains genes active in the presence of Polycomb complex
Erkek et al. show that in atypical teratoid rhabdoid tumors (ATRT), which often lack the SWI/SNF complex component SMARCB1, a large fraction of SMARCB1 binding loci in normal brain is bound by EZH2 but without H3K27me3 and remains in an active state, and some of these genes are essential for ATRT survival.
Atypical teratoid/rhabdoid tumors (AT/RTs) are highly aggressive brain tumors of early childhood poorly responding to therapy. The majority of cases show inactivation of SMARCB1 (INI1, hSNF5, BAF47), ...a core member of the adenosine triphosphate (ATP)-dependent SWI/SNF chromatin-remodeling complex. We here report the case of a supratentorial AT/RT in a 9-month-old boy, which showed retained SMARCB1 staining on immunohistochemistry and lacked genetic alterations of SMARCB1. Instead, the tumor showed loss of protein expression of another SWI/SNF chromatin-remodeling complex member, the ATPase subunit SMARCA4 (BRG1) due to a homozygous SMARCA4 mutation c.2032C>T (p.Q678X). Our findings highlight the role of SMARCA4 in the pathogenesis of SMARCB1-positive AT/RT and the usefulness of antibodies directed against SMARCA4 in this diagnostic setting.
PDF
