Infrequent RAS mutation is not associated with specific histological phenotype in gliomas.

BACKGROUND: Mutations in driver genes such as IDH and BRAF have been identified in gliomas. Meanwhile, dysregulations in the p53, RB1, and MAPK and/or PI3K pathways are involved in the molecular pathogenesis of glioblastoma. RAS family genes activate MAPK through activation of RAF and PI3K to promote cell proliferation. RAS mutations are a well-known driver of mutation in many types of cancers, but knowledge of their significance for glioma is insufficient. The purpose of this study was to reveal the frequency and the clinical phenotype of RAS mutant in gliomas. METHODS: This study analysed RAS mutations and their clinical significance in 242 gliomas that were stored as unfixed or cryopreserved specimens removed at Kyoto University and Osaka National Hospital between May 2006 and October 2017. The hot spots mutation of IDH1/2, H3F3A, HIST1H3B, and TERT promoter and exon 2 and exon 3 of KRAS, HRAS, and NRAS were analysed with Sanger sequencing method, and 1p/19q codeletion was analysed with multiplex ligation-dependent probe amplification. DNA methylation array was performed in some RAS mutant tumours to improve accuracy of diagnosis. RESULTS: RAS mutations were identified in four gliomas with three KRAS mutations and one NRAS mutation in one anaplastic oligodendroglioma, two anaplastic astrocytomas (IDH wild-type in each), and one ganglioglioma. RAS-mutant gliomas were identified with various types of glioma histology. CONCLUSION: RAS mutation appears infrequent, and it is not associated with any specific histological phenotype of glioma.

Systemic MEK inhibition enhances the efficacy of 5-aminolevulinic acid-photodynamic therapy.

BACKGROUND: Protoporphyrin IX (PpIX) gets accumulated preferentially in 5-aminolevulinic acid (5-ALA)-treated cancer cells. Photodynamic therapy (PDT) utilises the accumulated PpIX to trigger cell death by light-induced generation of reactive oxygen species (ROS). We previously demonstrated that oncogenic Ras/MEK decreases PpIX accumulation in cancer cells. Here, we investigated whether combined therapy with a MEK inhibitor would improve 5-ALA-PDT efficacy. METHODS: Cancer cells and mice models of cancer were treated with 5-ALA-PDT, MEK inhibitor or both MEK inhibitor and 5-ALA-PDT, and treatment efficacies were evaluated. RESULTS: Ras/MEK negatively regulates the cellular sensitivity to 5-ALA-PDT as cancer cells pre-treated with a MEK inhibitor were killed more efficiently by 5-ALA-PDT. MEK inhibition promoted 5-ALA-PDT-induced ROS generation and programmed cell death. Furthermore, the combination of 5-ALA-PDT and a systemic MEK inhibitor significantly suppressed tumour growth compared with either monotherapy in mouse models of cancer. Remarkably, 44% of mice bearing human colon tumours showed a complete response with the combined treatment. CONCLUSION: We demonstrate a novel strategy to promote 5-ALA-PDT efficacy by targeting a cell signalling pathway regulating its sensitivity. This preclinical study provides a strong basis for utilising MEK inhibitors, which are approved for treating cancers, to enhance 5-ALA-PDT efficacy in the clinic.

Characteristics and outcomes of elderly patients with diffuse gliomas: a multi-institutional cohort study by Kansai Molecular Diagnosis Network for CNS Tumors.

INTRODUCTION: This study investigates the current state of clinical practice and molecular analysis for elderly patients with diffuse gliomas and aims to elucidate treatment outcomes and prognostic factors of patients with glioblastomas. METHODS: We collected elderly cases (≥ 70 years) diagnosed with primary diffuse gliomas and enrolled in Kansai Molecular Diagnosis Network for CNS Tumors. Clinical and pathological characteristics were analyzed retrospectively. Various factors were evaluated in univariate and multivariate models to examine their effects on overall survival. RESULTS: Included in the study were 140 elderly patients (WHO grade II: 7, III: 19, IV: 114), median age was 75 years. Sixty-seven patients (47.9%) had preoperative Karnofsky Performance Status score of ≥ 80. All patients underwent resection (gross-total: 20.0%, subtotal: 14.3%, partial: 39.3%, biopsy: 26.4%). Ninety-six of the patients (68.6%) received adjuvant treatment consisting of radiotherapy (RT) with temozolomide (TMZ). Seventy-eight of the patients (75.0%) received radiation dose of ≥ 50 Gy. MGMT promoter was methylated in 68 tumors (48.6%), IDH1/2 was wild-type in 129 tumors (92.1%), and TERT promoter was mutated in 78 of 128 tumors (60.9%). Median progression-free and overall survival of grade IV cases was 8.2 and 13.6 months, respectively. Higher age (≥ 80 years) and TERT promoter mutated were associated with shorter survival. Resection and adjuvant RT + TMZ were identified as independent factors for good prognosis. CONCLUSIONS: This community-based study reveals characteristics and outcomes of elderly glioma patients in a real-world setting. Elderly patients have several potential factors for poor prognosis, but resection followed by RT + TMZ could lengthen duration of survival.

Pediatric thalamic glioma with H3F3A K27M mutation, which was detected before and after malignant transformation: a case report.

PURPOSE: Histone H3.3 (H3F3A) mutation in the codon for lysine 27 (K27M) has been found as driver mutations in pediatric glioblastoma and has been suggested to play critical roles in the pathogenesis of thalamic gliomas and diffuse intrinsic pontine gliomas. We report a case of thalamic glioma with H3F3A K27M mutation, which was detected in both the primary tumor diagnosed as diffuse astrocytoma obtained during the first surgery and also in the tumor diagnosed as anaplastic astrocytoma obtained at the second surgery. CASE PRESENTATION: A 14-year-old girl presented with mild headache. Magnetic resonance imaging (MRI) showed a small intraaxial lesion in the left thalamus, which increased in size. Stereotactic tumor biopsy was performed 2 years after the initial diagnosis, and a pathological diagnosis of diffuse astrocytoma (WHO grade 2) was made. The tumor grew further and showed contrast enhancement on MRI despite 16 months of chemotherapy. Surgical removal via the transcallosal approach was then performed, and postoperative pathological diagnosis was anaplastic astrocytoma (WHO grade 3), indicating malignant transformation of the tumor. Molecular diagnosis of tumor tissue obtained at first and second surgeries revealed H3F3A K27M mutation in both primary and secondary specimens. CONCLUSION: This report demonstrates minute neuroradiological and pathological features of malignant transformation from thalamic low grade glioma with H3F3A K27M mutation. It is noteworthy that this mutation was found in this case when the tumor was still a low-grade glioma. Tissue sampling for genetic analysis is useful in patients with thalamic gliomas to predict the clinical course and efficacy of treatments.

Ipsilateral hemiparesis caused by putaminal hemorrhage in a patient with horizontal gaze palsy with progressive scoliosis: a case report.

BACKGROUND: Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disorder caused by mutations in the ROBO3 gene, resulting in a critical absence of crossing fibers in the brainstem. CASE PRESENTATION: We present a patient with ipsilateral hemiparesis caused by putaminal hemorrhage who had a history of horizontal gaze paralysis and scoliosis since childhood. Diffusion tensor imaging (DTI) tractography confirmed the presence of uncrossed corticospinal tracts. Sequence analysis of the entire ROBO3 coding regions revealed a novel nonsense mutation. CONCLUSION: We report the first known HGPPS case with intracranial hemorrhage and ROBO3 mutation showing an absence of major crossing pathways by DTI.

Human-Induced Pluripotent Stem Cell-Derived Neural Progenitor Cells Showed Neuronal Differentiation, Neurite Extension, and Formation of Synaptic Structures in Rodent Ischemic Stroke Brains.

Ischemic stroke is a major cerebrovascular disease with high morbidity and mortality rates; however, effective treatments for ischemic stroke-related neurological dysfunction have yet to be developed. In this study, we generated neural progenitor cells from human leukocyte antigen major loci gene-homozygous-induced pluripotent stem cells (hiPSC-NPCs) and evaluated their therapeutic effects against ischemic stroke. hiPSC-NPCs were intracerebrally transplanted into rat ischemic brains produced by transient middle cerebral artery occlusion at either the subacute or acute stage, and their in vivo survival, differentiation, and efficacy for functional improvement in neurological dysfunction were evaluated. hiPSC-NPCs were histologically identified in host brain tissues and showed neuronal differentiation into vGLUT-positive glutamatergic neurons, extended neurites into both the ipsilateral infarct and contralateral healthy hemispheres, and synaptic structures formed 12 weeks after both acute and subacute stage transplantation. They also improved neurological function when transplanted at the subacute stage with γ-secretase inhibitor pretreatment. However, their effects were modest and not significant and showed a possible risk of cells remaining in their undifferentiated and immature status in acute-stage transplantation. These results suggest that hiPSC-NPCs show cell replacement effects in ischemic stroke-damaged neural tissues, but their efficacy is insufficient for neurological functional improvement after acute or subacute transplantation. Further optimization of cell preparation methods and the timing of transplantation is required to balance the efficacy and safety of hiPSC-NPC transplantation.

Prediction of MGMT promotor methylation status in glioblastoma by contrast-enhanced T1-weighted intensity image.

Background: The study aims to explore MRI phenotypes that predict glioblastoma's (GBM) methylation status of the promoter region of MGMT gene (pMGMT) by qualitatively assessing contrast-enhanced T1-weighted intensity images. Methods: A total of 193 histologically and molecularly confirmed GBMs at the Kansai Network for Molecular Diagnosis of Central Nervous Tumors (KANSAI) were used as an exploratory cohort. From the Cancer Imaging Archive/Cancer Genome Atlas (TCGA) 93 patients were used as validation cohorts. "Thickened structure" was defined as the solid tumor component presenting circumferential extension or occupying >50% of the tumor volume. "Methylated contrast phenotype" was defined as indistinct enhancing circumferential border, heterogenous enhancement, or nodular enhancement. Inter-rater agreement was assessed, followed by an investigation of the relationship between radiological findings and pMGMT methylation status. Results: Fleiss's Kappa coefficient for "Thickened structure" was 0.68 for the exploratory and 0.55 for the validation cohort, and for "Methylated contrast phenotype," 0.30 and 0.39, respectively. The imaging feature, the presence of "Thickened structure" and absence of "Methylated contrast phenotype," was significantly predictive of pMGMT unmethylation both for the exploratory (p = .015, odds ratio = 2.44) and for the validation cohort (p = .006, odds ratio = 7.83). The sensitivities and specificities of the imaging feature, the presence of "Thickened structure," and the absence of "Methylated contrast phenotype" for predicting pMGMT unmethylation were 0.29 and 0.86 for the exploratory and 0.25 and 0.96 for the validation cohort. Conclusions: The present study showed that qualitative assessment of contrast-enhanced T1-weighted intensity images helps predict GBM's pMGMT methylation status.

Neuroradiological, genetic and clinical characteristics of histone H3 K27-mutant diffuse midline gliomas in the Kansai Molecular Diagnosis Network for CNS Tumors (Kansai Network): multicenter retrospective cohort.

This study aims to elucidate the clinical and molecular characteristics, treatment outcomes and prognostic factors of patients with histone H3 K27-mutant diffuse midline glioma. We retrospectively analyzed 93 patients with diffuse midline glioma (47 thalamus, 24 brainstem, 12 spinal cord and 10 other midline locations) treated at 24 affiliated hospitals in the Kansai Molecular Diagnosis Network for CNS Tumors. Considering the term "midline" areas, which had been confused in previous reports, we classified four midline locations based on previous reports and anatomical findings. Clinical and molecular characteristics of the study cohort included: age 4-78 years, female sex (41%), lower-grade histology (56%), preoperative Karnofsky performance status (KPS) scores ≥ 80 (49%), resection (36%), adjuvant radiation plus chemotherapy (83%), temozolomide therapy (76%), bevacizumab therapy (42%), HIST1H3B p.K27M mutation (2%), TERT promoter mutation (3%), MGMT promoter methylation (9%), BRAF p.V600E mutation (1%), FGFR1 mutation (14%) and EGFR mutation (3%). Median progression-free and overall survival time was 9.9 ± 1.0 (7.9-11.9, 95% CI) and 16.6 ± 1.4 (13.9-19.3, 95% CI) months, respectively. Female sex, preoperative KPS score ≥ 80, adjuvant radiation + temozolomide and radiation ≥ 50 Gy were associated with favorable prognosis. Female sex and preoperative KPS score ≥ 80 were identified as independent good prognostic factors. This study demonstrated the current state of clinical practice for patients with diffuse midline glioma and molecular analyses of diffuse midline glioma in real-world settings. Further investigation in a larger population would contribute to better understanding of the pathology of diffuse midline glioma.

Adducted thumb may not be mandatory for prenatal diagnosis of X-linked hydrocephalus in early second trimester.

OBJECTIVE: X-linked hydrocephalus (XLH), the most common genetic hydrocephalus, is caused by mutation of the L1 cell adhesion molecule (L1CAM). A fetus/neonate with this disorder frequently shows an adducted thumb, which has been employed as a helpful finding in the prenatal diagnosis of XLH. MATERIALS AND METHODS: We describe a male fetus with hydrocephalus without an adducted thumb: the pregnancy was terminated at 21 weeks' gestation on the parents' request. Direct sequencing of the umbilical cord revealed L1CAM mutation, which confirmed the diagnosis of XLH. RESULTS: Our literature review demonstrated that while an adducted thumb was observed in almost all fetuses with this disorder after 24 weeks' gestation, it was noted in only 57% (8/14) of fetuses/neonates at less than 24 weeks: it was absent in 43%. CONCLUSION: Even if an adducted thumb is not observed, XLH should not be ruled out, especially in early gestation.

Genetic Alteration May Proceed with a Histological Change in Glioblastoma: A Report from Initially Diagnosed as Nontumor Lesion Cases.

Despite recent signs of progress in diagnostic radiology, it is quite rare that a glioblastoma (GBM) is detected asymptomatically. We describe two patients with asymptomatic nonenhancing GBMs that were not diagnosed with neoplasia at first. The patients had brain scans as medical checkups, and incidentally lesions were detected. In both cases, surgical specimens histopathologically showed no evidence of neoplasia, whereas molecular genetic findings were isocitrate dehydrogenase (IDH)-wildtype, O6-methylguanine-DNA methyltransferase promoter (pMGMT) unmethylated, and telomerase reverse transcriptase (TERT) promoter mutated, which matched to GBM. One patient was observed without adjuvant therapy and the tumor recurred 7 months later. Reoperation was performed, and histopathologically GBM was confirmed with the same molecular diagnosis as the first surgical specimen. Another patient was carefully observed, and chemoradiotherapy was begun 6 months after the operation following the extension of the lesion. Eventually, because of disease progression, both patients deceased. We postulate that in each case, the tumor was not lower-grade glioma but corresponded to the early growth phase of GBM cells. Thus far, cases of malignant transformation from lower-grade glioma or asymptomatic GBM with typical histologic features are reported. Nevertheless, to the best of our knowledge, no such case of nonenhancing, nonhistologically confirmed GBM was reported. We conjecture these cases shed light on the yet unknown natural history of GBM. GBM can take the form of radiological nonenhancing and histological nonneoplastic fashion before typical morphology. Molecular genetic analysis can diagnose atypical preceding GBM, and we recommend early surgical removal and adjuvant treatment.

Revisiting the definition of glioma recurrence based on a phylogenetic investigation of primary and re-emerging tumor samples: a case report.

A recurrent tumor is defined as a re-emerging subclone originating from an ancestorial clone of the primary neoplasm. Hence, it should be distinguished from de novo tumor emerging from other clones. Herein, we describe an exceptional case in which the locally re-emerging glioma did not share genetic alterations of the primary tumor. While the initial tumor harbored mutations in IDH1 and TERT genes as well as 1p/19q codeletion, the re-emerging tumor did not present any of these genetic abnormalities. Variant calling for tumor samples using whole-genome sequencing revealed that 1696 mutations within the primary tumor faded in the re-emerging tumor, and that 4591 mutations were newly detected in the re-emerging tumor. These results suggested that the initial and re-emerging tumors did not share same clonal origins, although the second tumor appeared adjacent to the old surgical cavity 5 years after the initial surgery. We finally speculated that the re-emerging tumor could be a "de novo glioma" or "radiation-induced glioblastoma following treatment of a diffuse glioma." This case highlights the importance of molecular re-evaluation of clinically diagnosed "recurrent" glioma lesions.

Prognostic stratification for IDH-wild-type lower-grade astrocytoma by Sanger sequencing and copy-number alteration analysis with MLPA.

The characteristics of IDH-wild-type lower-grade astrocytoma remain unclear. According to cIMPACT-NOW update 3, IDH-wild-type astrocytomas with any of the following factors show poor prognosis: combination of chromosome 7 gain and 10 loss (+ 7/- 10), and/or EGFR amplification, and/or TERT promoter (TERTp) mutation. Multiplex ligation-dependent probe amplification (MLPA) can detect copy number alterations at reasonable cost. The purpose of this study was to identify a precise, cost-effective method for stratifying the prognosis of IDH-wild-type astrocytoma. Sanger sequencing, MLPA, and quantitative methylation-specific PCR were performed for 42 IDH-wild-type lower-grade astrocytomas surgically treated at Kyoto University Hospital, and overall survival was analysed for 40 patients who underwent first surgery. Of the 42 IDH-wild-type astrocytomas, 21 were classified as grade 4 using cIMPACT-NOW update 3 criteria and all had either TERTp mutation or EGFR amplification. Kaplan-Meier analysis confirmed the prognostic significance of cIMPACT-NOW criteria, and World Health Organization grade was also prognostic. Cox regression hazard model identified independent significant prognostic indicators of PTEN loss (risk ratio, 9.75; p < 0.001) and PDGFRA amplification (risk ratio, 13.9; p = 0.002). The classification recommended by cIMPACT-NOW update 3 could be completed using Sanger sequencing and MLPA. Survival analysis revealed PTEN and PDGFRA were significant prognostic factors for IDH-wild-type lower-grade astrocytoma.

Topoisomerase IIß immunoreactivity (IR) co-localizes with neuronal marker-IR but not glial fibrillary acidic protein-IR in GLI3-positive medulloblastomas: an immunohistochemical analysis of 124 medulloblastomas from the Japan Children's Cancer Group.

We previously reported observing GLI3 in medulloblastomas expressing neuronal markers (NM) and/or glial fibrillary acidic protein (GFAP). Furthermore, patients with medulloblastomas expressing NM or GFAP tended to show favorable or poor prognosis, respectively. In the present study, we focused on the role of topoisomerase IIß (TOP2ß) as a possible regulator for neuronal differentiation in medulloblastomas and examined the pathological roles of GLI3, NM, GFAP, and TOP2ß expressions in a larger population. We divided 124 medulloblastomas into three groups (NM-/GFAP-, NM +/GFAP-, and GFAP +) based on their immunoreactivity (IR) against NM and GFAP. The relationship among GLI3, NM, GFAP, and TOP2ß was evaluated using fluorescent immunostaining and a publicly available single-cell RNA sequencing dataset. In total, 87, 30, and 7 medulloblastomas were classified as NM-/GFAP-, NM + /GFAP-, and GFAP +, and showed intermediate, good, and poor prognoses, respectively. GLI3-IR was frequently observed in NM +/GFAP- and GFAP + , and TOP2ß-IR was frequently observed only in NM +/GFAP- medulloblastomas. In fluorescent immunostaining, TOP2ß-IR was mostly co-localized with NeuN-IR but not with GFAP-IR. In single-cell RNA sequencing, TOP2ß expression was elevated in CMAS/DCX-positive, but not in GFAP-positive, cells. NM-IR and GFAP-IR are important for estimating the prognosis of patients with medulloblastoma; hence they should be assessed in clinical practice.

MEK reduces cancer-specific PpIX accumulation through the RSK-ABCB1 and HIF-1α-FECH axes.

The efficacy of aminolevulinic acid (5-ALA)-based photodynamic diagnosis (5-ALA-PDD) and photodynamic therapy (5-ALA-PDT) is dependent on 5-ALA-induced cancer-specific accumulation of protoporphyrin IX (PpIX). We previously reported that inhibition of oncogenic Ras/MEK increases PpIX accumulation in cancer cells by reducing PpIX efflux through ATP-binding cassette sub-family B member 1 (ABCB1) and ferrochelatase (FECH)-catalysed PpIX conversion to haem. Here, we sought to identify the downstream pathways of Ras/MEK involved in the regulation of PpIX accumulation via ABCB1 and FECH. First, we demonstrated that Ras/MEK activation reduced PpIX accumulation in RasV12-transformed NIH3T3 cells and HRAS transgenic mice. Knockdown of p90 ribosomal S6 kinases (RSK) 2, 3, or 4 increased PpIX accumulation in RasV12-transformed NIH3T3 cells. Further, treatment with an RSK inhibitor reduced ABCB1 expression and increased PpIX accumulation. Moreover, HIF-1α expression was reduced when RasV12-transformed NIH3T3 cells were treated with a MEK inhibitor, demonstrating that HIF-1α is a downstream element of MEK. HIF-1α inhibition decreased FECH activity and increased PpIX accumulation. Finally, we demonstrated the involvement of RSKs and HIF-1α in the regulation of PpIX accumulation in human cancer cell lines. These results demonstrate that the RSK-ABCB1 and HIF-1α-FECH axes are the downstream pathways of Ras/MEK involved in the regulation of PpIX accumulation.

TERT promoter mutation associated with multifocal phenotype and poor prognosis in patients with IDH wild-type glioblastoma.

BACKGROUND: Although mutations in the promoter region of the telomerase reverse transcriptase (TERTp) gene are the most common alterations in glioblastoma (GBM), their clinical significance remains unclear. Therefore, we investigated the impact of TERTp status on patient outcome and clinicopathological features in patients with GBM over a long period of follow-up. METHODS: We retrospectively analyzed 153 cases of GBM. Six patients with isocitrate dehydrogenase 1 (IDH1) or H3F3A gene mutations were excluded from this study. Among the 147 cases of IDH wild-type GBM, 92 (62.6%) had the TERTp mutation. Clinical, immunohistochemical, and genetic factors (BRAF, TP53 gene mutation, CD133, ATRX expression, O 6-methylguanine-DNA methyltransferase [MGMT] promoter methylation) and copy number alterations (CNAs) were investigated. RESULTS: GBM patients with the TERTp mutation were older at first diagnosis versus those with TERTp wild type (66.0 vs. 60.0 years, respectively, P = .034), and had shorter progression-free survival (7 vs. 10 months, respectively, P = .015) and overall survival (16 vs. 24 months, respectively, P = .017). Notably, magnetic resonance imaging performed showed that TERTp-mutant GBM was strongly associated with multifocal/distant lesions (P = .004). According to the CNA analysis, TERTp mutations were positively correlated with EGFR amp/gain, CDKN2A deletion, and PTEN deletion; however, these mutations were negatively correlated with PDGFR amp/gain, CDK4 gain, and TP53 deletion. CONCLUSIONS: TERTp mutations were strongly correlated with multifocal/distant lesions and poor prognosis in patients with IDH wild-type GBM. Less aggressive GBM with TERTp wild type may be a distinct clinical and molecular subtype of IDH wild-type GBM.

Molecular characteristics and clinical outcomes of elderly patients with IDH-wildtype glioblastomas: comparative study of older and younger cases in Kansai Network cohort.

Aging is a known negative prognostic factor in glioblastomas (GBM). Whether particular genetic backgrounds are a factor in poor outcomes of elderly patients with GBM warrants investigation. We aim to elucidate any differences between older and younger adult patients with IDH-wildtype GBM regarding both molecular characteristics and clinical outcomes. We collected adult cases diagnosed with IDH-wildtype GBM from the Kansai Network. Clinical and pathological characteristics were analyzed retrospectively and compared between older (≥ 70 years) and younger (≤ 50 years) cases. Included were 92 older vs. 33 younger cases. The older group included more patients with preoperative Karnofsky performance status score < 70 and had a shorter survival time than the younger group. MGMT promoter was methylated more frequently in the older group. TERT promoter mutation was more common in the older group. There were significant differences in DNA copy-number alteration profiles between age groups in PTEN deletion and CDK4 amplification/gain. In the older group, no molecular markers were identified, but surgical resection was an independent prognostic factor. Age-specific survival difference was significant in the MGMT methylated and TERT wildtype subgroup. Elderly patients have several potential factors in poor prognosis of glioblastomas. Varying molecular profiles may explain differing rates of survival between generations.

Activated leukocyte cell adhesion molecule expression correlates with the WNT subgroup in medulloblastoma and is involved in regulating tumor cell proliferation and invasion.

Cluster of differentiation (CD) 166 or activated leukocyte cell adhesion molecule (ALCAM) is a transmembrane molecule known to be an intercellular adhesion factor. The expression and function of ALCAM in medulloblastoma (MB), a pediatric brain tumor with highly advanced molecular genetics, remains unclear. Therefore, this study aimed to clarify the significance and functional role of ALCAM expression in MB. ALCAM expression in 45 patients with MB was evaluated by immunohistochemical analysis of formalin-fixed paraffin-embedded clinical specimens and the relationship between ALCAM expression and pathological type/molecular subgroup, such as WNT, SHH, Group 3, and Group 4, was examined. Eight ALCAM positive (18%), seven partially positive (16%), and 30 negative (67%) cases were detected. All seven cases of the WNT molecular subgroup were ALCAM positive and ALCAM expression strongly correlated with this subgroup (P < 0.0001). In addition, functional studies using MB cell lines revealed ALCAM expression affected proliferation and migration as a positive regulator in vitro. However, ALCAM silencing did not affect survival or the formation of leptomeningeal dissemination in an orthotopic mouse model, but did induce a malignant phenotype with increased tumor cell invasion at the dissemination sites (P = 0.0029). In conclusion, our results revealed that ALCAM exhibited highly specific expression in the WNT subgroup of MB. Furthermore, we demonstrated that the cell kinetics of MB cell lines can be altered by the expression of ALCAM.

Distribution differences in prognostic copy number alteration profiles in IDH-wild-type glioblastoma cause survival discrepancies across cohorts.

The diagnosis and prognostication of glioblastoma (GBM) remain to be solely dependent on histopathological findings and few molecular markers, despite the clinical heterogeneity in this entity. To address this issue, we investigated the prognostic impact of copy number alterations (CNAs) using two population-based IDH-wild-type GBM cohorts: an original Japanese cohort and a dataset from The Cancer Genome Atlas (TCGA). The molecular disproportions between these cohorts were dissected in light of cohort differences in GBM. The Japanese cohort was collected from cases registered in Kansai Molecular Diagnosis Network for CNS tumors (KNBTG). The somatic landscape around CNAs was analyzed for 212 KNBTG cases and 359 TCGA cases. Next, the clinical impacts of CNA profiles were investigated for 140 KNBTG cases and 152 TCGA cases treated by standard adjuvant therapy using temozolomide-based chemoradiation. The comparative profiling indicated unequal distribution of specific CNAs such as EGFR, CDKN2A, and PTEN among the two cohorts. Especially, the triple overlap CNAs in these loci (triple CNA) were much higher in frequency in TCGA (70.5%) than KNBTG (24.3%), and its prognostic impact was independently validated in both cohorts. The KNBTG cohort significantly showed better prognosis than the TCGA cohort (median overall survival 19.3 vs 15.6 months). This survival difference between the two cohorts completely resolved after subclassifying all cases according to the triple CNA status. The prognostic significance of triple CNA was identified in IDH-wild-type GBM. Distribution difference in prognostic CNA profiles potentially could cause survival differences across cohorts in clinical studies.

Radiomics and MGMT promoter methylation for prognostication of newly diagnosed glioblastoma.

We attempted to establish a magnetic resonance imaging (MRI)-based radiomic model for stratifying prognostic subgroups of newly diagnosed glioblastoma (GBM) patients and predicting O (6)-methylguanine-DNA methyltransferase promotor methylation (pMGMT-met) status of the tumor. Preoperative MRI scans from 201 newly diagnosed GBM patients were included in this study. A total of 489 texture features including the first-order feature, second-order features from 162 datasets, and location data from 182 datasets were collected. Supervised principal component analysis was used for prognostication and predictive modeling for pMGMT-met status was performed based on least absolute shrinkage and selection operator regression. 22 radiomic features that were correlated with prognosis were used to successfully stratify patients into high-risk and low-risk groups (p = 0.004, Log-rank test). The radiomic high- and low-risk stratification and pMGMT status were independent prognostic factors. As a matter of fact, predictive accuracy of the pMGMT methylation status was 67% when modeled by two significant radiomic features. A significant survival difference was observed among the combined high-risk group, combined intermediate-risk group (this group consists of radiomic low risk and pMGMT-unmet or radiomic high risk and pMGMT-met), and combined low-risk group (p = 0.0003, Log-rank test). Radiomics can be used to build a prognostic score for stratifying high- and low-risk GBM, which was an independent prognostic factor from pMGMT methylation status. On the other hand, predictive accuracy of the pMGMT methylation status by radiomic analysis was insufficient for practical use.

Prediction of IDH and TERT promoter mutations in low-grade glioma from magnetic resonance images using a convolutional neural network.

Identification of genotypes is crucial for treatment of glioma. Here, we developed a method to predict tumor genotypes using a pretrained convolutional neural network (CNN) from magnetic resonance (MR) images and compared the accuracy to that of a diagnosis based on conventional radiomic features and patient age. Multisite preoperative MR images of 164 patients with grade II/III glioma were grouped by IDH and TERT promoter (pTERT) mutations as follows: (1) IDH wild type, (2) IDH and pTERT co-mutations, (3) IDH mutant and pTERT wild type. We applied a CNN (AlexNet) to four types of MR sequence and obtained the CNN texture features to classify the groups with a linear support vector machine. The classification was also performed using conventional radiomic features and/or patient age. Using all features, we succeeded in classifying patients with an accuracy of 63.1%, which was significantly higher than the accuracy obtained from using either the radiomic features or patient age alone. In particular, prediction of the pTERT mutation was significantly improved by the CNN texture features. In conclusion, the pretrained CNN texture features capture the information of IDH and TERT genotypes in grade II/III gliomas better than the conventional radiomic features.