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.

Subtyping of Group 3/4 medulloblastoma as a potential prognostic biomarker among patients treated with reduced dose of craniospinal irradiation: a Japanese Pediatric Molecular Neuro-Oncology Group study

BACKGROUND

One of the most significant challenges in patients with medulloblastoma is reducing the dose of craniospinal irradiation (CSI) to minimize neurological sequelae in survivors. Molecular characterization of patients receiving lower than standard dose of CSI therapy is important to facilitate further reduction of treatment burden.

METHODS

We conducted DNA methylation analysis using an Illumina Methylation EPIC array to investigate molecular prognostic markers in 38 patients with medulloblastoma who were registered in the Japan Pediatric Molecular Neuro-Oncology Group and treated with reduced-dose CSI.

RESULTS

Among the patients, 23 were classified as having a standard-risk and 15 as high-risk according to the classic classification based on tumor resection rate and presence of metastasis, respectively. The median follow-up period was 71.5 months (12.0-231.0). The median CSI dose was 18 Gy (15.0-24.0) in both groups, and 5 patients in the high-risk group received a CSI dose of 18.0 Gy. Molecular subgrouping revealed that the standard-risk cohort included 5 WNT, 2 SHH, and 16 Group 3/4 cases; all 15 patients in the high-risk cohort had Group 3/4 medulloblastoma. Among the patients with Group 3/4 medulloblastoma, 9 of the 31 Group 3/4 cases were subclassified as subclass II, III, and V, which were known to an association with poor prognosis according to the novel subtyping among the subgroups. Patients with poor prognostic subtype showed worse prognosis than that of others (5-year progression survival rate 90.4% vs. 22.2%; p < 0.0001). The result was replicated in the multivariate analysis (hazard ratio12.77, 95% confidence interval for hazard ratio 2.38-99.21, p value 0.0026 for progression-free survival, hazard ratio 5.02, 95% confidence interval for hazard ratio 1.03-29.11, p value 0.044 for overall survival).

CONCLUSION

Although these findings require validation in a larger cohort, the present findings suggest that novel subtyping of Group 3/4 medulloblastoma may be a promising prognostic biomarker even among patients treated with lower-dose CSI than standard treatment.

Human induced pluripotent stem cell line (ONHi001-A) generated from a patient with infantile neuroaxonal dystrophy having PLA2G6 c.517C > T (p.Q173X) and c.1634A > G (p.K545R) compound heterozygous mutations

Infantile neuroaxonal dystrophy (INAD) is a rare neurodegenerative disease caused mainly by homozygous or compound heterozygous mutations in the PLA2G6 gene. We generated a human induced pluripotent stem cell (hiPSC) line (ONHi001-A) using fibroblasts derived from a patient with INAD. The patient exhibited c.517C > T (p.Q173X) and c.1634A > G (p.K545R) compound heterozygous mutations in the PLA2G6 gene. This hiPSC line may be useful for studying the pathogenic mechanism underlying INAD.

MPC-15 CLINICAL FEATURE OF NON-MIDLINE GLIOMA WITH H3F3A GENE MUTATION

Introduction

Diffuse midline glioma (DMG), H3K27-altered, is a CNS WHO grade 4 glioma that usually occurs mainly in the brainstem region in children and also in the thalamus and spinal cord in older children and adults. On the other hand, glioma with histone H3 p. G34R/V mutations in the cerebral hemispheres are defined in a new classification of Diffuse hemispheric glioma, H3G34-mutant (DHG), in the WHO 2021 classification. However, there are some reports of H3K27-altered non-midline gliomas (NDMG) that are not located in the midline, but the differences between these hemispheric tumors with mutations in different regions of histone H3 are unknown. In this study, we report a comparative study of the clinical characteristics between two groups of glioma, H3K27-altered NDMGs and H3G34-mutant DHGs.

Methods

Among 4128 brain tumor specimens collected in the Kansai Network for Molecular Diagnosis of Central Nervous System Tumors, 25 NDMG cases, excluding 93 cases defined as DMG, were included out of 118 cases with mutations in the H3F3A gene. Both 16 H3K27-altered NDMG cases and 9 H3G34-mutant DHG cases were examined for comparison of clinical characteristics.

Results

There were no differences in gender, tumor location, or pathology between NDMG and DHG. The median age was 47.3 years in NDMG and 26.2 years in DHG, and NDMG was significantly older than DHG (p=0.003). The rate of MGMT promoter methylation is no significant difference between 4 cases (25%) in NDMG and 6 cases (66.7%) in DHG (p=0.087). The Kaplan-Meier survival curve showed no significant difference, with a median survival of 495 days for NDMG and 587 days for DHG (p=0.765).

Discussion and Conclusion

We reported on gliomas with H3F3A mutations that occur in the cerebral hemispheres. We compared the clinical characteristics of NDMG with H3K27-altered and DHG with H3G34-mutant, which have similar tumor locations of occurrence.

MPC-8 CLINICAL CHARACTERISTICS OF H3 K27-MUTATED GLIOMAS AT MIDLINE AND NEAR MIDLINE

Background and Purpose

Diffuse midline glioma(DMG),H3K27 alterd (WHO 2021, CNS grade 4) is a type of tumor that mainly develops in the CNS's median. However, owing to its rarity, few comprehensive reports have been published. This report conducted a retrospective study on H3p.K27M mutation cases via the Kansai Molecular Diagnosis Network for CNS tumors.

Materials and Methods

H3p.K27M mutation cases were analyzed out of 4128 total gene analysis specimens submitted for suspected glioma during the case accumulation period from May 2007 to July 2022.

Results

There were 109 cases with the H3p.K27M mutation, of which 107 had the H3F3A mutation, and 2 had the HIST1H3B mutation. Of the 93cases that developed a tumor on or around the lateral ventricles of the brain along the midline of the CNS, affected sites included the thalamus (37 cases), brainstem (19 cases), spinal cord (11 cases), and other areas (15 cases), while 7 cases were of multifocal origin and 4 cases were unclassifiable. The patients' ages ranged from 4 to 76 years, with a mean and median age of 32.8 and 30 years, respectively (n = 88). The male to female ratio was 52:36. All cases had IDH-wild type with pMGMT methylation (9.6%), pTERT mutation (3.2%), TP53 mutation (56.5%), BRAF V600E mutation (1.1%), FGFR1 mutation (14.3%), or EGFR mutation (3.3%). Histopathological examination revealed the existence of WHO CNS grade 2, 3, and 4 tumors. Overall survival (OS) was confirmed in 38 cases, with a mean and median age of 15.0 and 11.9 months, respectively. The results of 51 cases in which prognosis was followed up on, suggested that the factors that contributed to the prolongation of OS were female sex (p = 0.0335), thalamus location (p = 0.0366), and irradiation of 50 Gy or more (p = 0.0237).

Discussion/Conclusion

Based on a literature review, we report on the clinical characteristics of DMG in our cases, including the category of midline in DMG.

BIOS-05. SANGER SEQUENCING AND COPY-NUMBER ALTERATION ANALYSIS WITH MLPA CAN CLINICALLY CLASSIFY IDH-WILD-TYPE LOWER-GRADE ASTROCYTOMA

The IDH-wild-type lower-grade astrocytomas are a heterogeneous entity. According to 2021 WHO classification, 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 with a reasonable cost. The purpose of this study was to find precise and cost-effective method for stratifying the prognosis of IDH-wild-type astrocytomas. 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 analyzed for 40 patients. Of the 42 IDH-wild-type astrocytomas, 21 were classified as grade 4 in 2021 WHO classification and all of them had either TERTp mutation or EGFR amplification. Kaplan-Meier analysis confirmed the prognostic significance of 2021 WHO Classification, and WHO grade was also prognostic. Cox regression hazard model identified PTEN loss and PDGFRA amplification as independent significant prognostic indicators (Risk ratio of 9.75, p&lt; 0.001 and 13.9, p=0.002). The classification recommended by 2021 WHO Classification could be completed using Sanger sequencing and MLPA. Survival analysis revealed PTEN and PDGFRA were significant prognostic factors for IDH-wild-type lower-grade astrocytomas.

Failure of human rhombic lip differentiation underlies medulloblastoma formation

Medulloblastoma (MB) comprises a group of heterogeneous paediatric embryonal neoplasms of the hindbrain with strong links to early development of the hindbrain^1-4. Mutations that activate Sonic hedgehog signalling lead to Sonic hedgehog MB in the upper rhombic lip (RL) granule cell lineage^5-8. By contrast, mutations that activate WNT signalling lead to WNT MB in the lower RL^9,10. However, little is known about the more commonly occurring group 4 (G4) MB, which is thought to arise in the unipolar brush cell lineage^3,4. Here we demonstrate that somatic mutations that cause G4 MB converge on the core binding factor alpha (CBFA) complex and mutually exclusive alterations that affect CBFA2T2, CBFA2T3, PRDM6, UTX and OTX2. CBFA2T2 is expressed early in the progenitor cells of the cerebellar RL subventricular zone in Homo sapiens, and G4 MB transcriptionally resembles these progenitors but are stalled in developmental time. Knockdown of OTX2 in model systems relieves this differentiation blockade, which allows MB cells to spontaneously proceed along normal developmental differentiation trajectories. The specific nature of the split human RL, which is destined to generate most of the neurons in the human brain, and its high level of susceptible EOMES⁺KI67⁺ unipolar brush cell progenitor cells probably predisposes our species to the development of G4 MB.

MEDB-30. Subclassification of Group 3/4 medulloblastoma as a potential prognostic biomarker to reduce the dose of craniospinal irradiation in patients with metastatic tumors: A Japanese Pediatric Molecular Neuro-Oncology Group study

BACKGROUND: In patients with medulloblastoma, one of the most significant challenges is to reduce the dose of craniospinal irradiation (CSI) to minimize neurological sequelae in survivors. Molecular characterization of patients treated using lower-dose CSI rather than standard therapy is important for further reducing the treatment burden. METHODS: We conducted DNA methylation analysis using an Illumina Methylation EPIC array to investigate molecular prognostic markers in 38 patients with medulloblastoma who were registered in the Japan Pediatric Molecular Neuro-Oncology Group and were treated using lower-dose CSI rather than standard-dose radiation therapy. RESULTS: Among the patients, 23 were classified as having a “standard-risk” and 15 as having a “high-risk” according to the classic classification based on tumor resection rate and presence of metastasis, respectively. The median follow-up period was 71.5 months. The median CSI dose was 18 Gy in both groups, and 10 patients in the “high-risk” group received a CSI dose of 23.4 Gy or 24 Gy. Molecular subgrouping revealed the “standard-risk” cohort included 5 WNT, 2 SHH, and 16 Group 3/4 cases; all 15 patients in the “high-risk” cohort had Group 3/4 medulloblastoma. Among the patients with Group 3/4 medulloblastoma, 13 of the 16 “standard-risk” patients were subclassified as subtypes I, IV, VI, and VII, which were associated with a good prognosis according to the novel sub-subclassification among Group 3/4 medulloblastomas. However, only 6 of the 15 “high-risk” patients were included in the subtypes. The good prognostic subtype cases among “high-risk” cohort were all survived without recurrence, in contrast to a worse prognosis (5-year progression free survival=33.3%; p=0.01) of the other cases. CONCLUSION: Although these findings require validation in a larger cohort, the present findings suggest that the novel sub-subclassification of Group 3/4 medulloblastoma may be a promising prognostic biomarker for reducing the dose of CSI in patients with metastatic medulloblastoma.

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.

TB-8 Genetic and molecular properties of long-term proliferating tumorsphere -forming glioma derived cells

Long-term proliferating tumorsphere-forming glioma derived cells (LTP-TS-GDCs) and patient derived xenografts (PDXs) are essential tools for translational research for glioma. However, only small subsets of glioma samples are established as LTP-TS and/or PDXs and little is known about the genetics and molecular properties of LTP-TS -forming GDCs and PDX. In this study, we aim to analyze the characteristics of LTP-TS -forming GDCs and PDXs. We tried primary sphere cultures from 56 glioma patient-derived samples and established 11 LTP-TS-GDCs out of 45 glioblastoma samples and no long-term sphere culture was isolated from grade3 and grade 2 gliomas. LTP-TS-GDCs had self-renewal ability and possessed certain multipotency. However, they significantly less expressed SOX1 FOXG1 and TUBB3, whereas they expressed LGALS1 and EN1 significantly higher than normal neural stem/progenitor cells. In addition, we found that LTP-TS-GDCs shared the same genetic profiles with original patients’ tumors. Furthermore, we investigated the genetic differences between the glioma tissues which were successfully established as LTP-TS-GDCs and those which were not. We found that glioma tissues with TERT promotor mutations and triple copy number alteration (CNA) [EGFR, CDKN2A, and PTEN loci] are significantly established as LTP-TS-GDCs. Lastly, we next investigated in vivo characteristics of glioma PDXs. We have injected glioma PDXs lines into immunodeficient mice brains and histopathologically analyzed the characteristics of xenografts. Each xenograft well recapitulated histological features of original patients’ tumors and tumor cells remarkably invade through subventricular zone. In conclusion, each LTP-TS-GDCs and PDXs had various gene expression profiles, reflecting intratumoral and interpatient heterogeneities of glioma. In addition, TERT promotor mutations and triple CNA significantly correlated with success rate of LTP-TS-GDCs. These findings will be of use and advance the preclinical and translational researches of glioma.

MPC-6 Clinical significance of whole chromosomal aberration signatures in non-metastatic medulloblastomas treated with 18Gy of craniospinal irradiation

Background: One of the most significant challenges is a reduction in the dose of craniospinal irradiation (CSI) in patients with medulloblastoma to minimize neurological sequelae. However, a North American clinical trial failed to show the prognostic non-inferiority of lower-dose irradiation compared to that associated with standard-dose radiation therapy for non-metastatic medulloblastomas. A European retrospective study revealed that whole chromosomal aberration signatures (WCASs) are a potential prognostic factor in Group 3/4 medulloblastoma without metastasis, but whether the molecular signature has the same clinical impact in patients treated with lower-dose CSI remains unknown. Methods: We conducted DNA methylation analysis using an Illumina Infinium Human Methylation EPIC BeadChip array to investigate molecular prognostic markers in 23 medulloblastoma patients who were registered in the Japan Pediatric Molecular Neuro-Oncology Group and treated with lower-dose CSI relative to standard treatment. A WCAS was defined as the presence of at least two of three chromosomal changes as follows: chromosome (chr) 7 gain, chr 8 loss, and chr 11 gain.Results: All patients presented with no residue or a residual tumor smaller than 1.5 cm2 after surgery without metastasis. The median age at onset was 6.9 years, and the median follow-up period was 80.6 months. CSI was delivered at a median dose of 18.0 Gy. Regarding molecular subgrouping, there were 5 WNT, 2 SHH, 1 Group 3, and 15 Group 4 medulloblastomas. Seven patients with Group 3/4 medulloblastomas showed WCASs and had significantly better prognosis than those without the alteration (5-year progression-free survival 100% vs. 63%, p = 0.046). Two late relapses occurred at 89 and 115 months after diagnosis, respectively, and one of these patients presented with a WCAS.Conclusion: WCAS may be a molecular prognostic marker not only in patients with medulloblastoma treated with standard-dose CSI but also in those treated with lower-dose irradiation.

TMOD-05. GENETIC AND MOLECULAR PROPERTIES OF LONG-TERM PROLIFERATING TUMORSPHERE -FORMING GLIOMA DERIVED CELLS

Long-term proliferating tumorsphere (LTP-TS)-forming glioma derived cells (GDCs) and patient derived xenografts (PDXs) are essential tools for translational research for glioma. However, only small subsets of glioma samples are established as LTP-TS and/or PDXs and little is known about the genetics and molecular properties of LTP-TS -forming GDCs and PDX. In this study, we aim to analyze the characteristics of LTP-TS -forming GDCs and PDXs. We tried primary sphere cultures from 56 glioma patient-derived samples and established 14 LTP-TS -forming GDCs out of 48 glioblastoma samples and no long-term sphere culture was isolated from grade3 and grade 2 gliomas. LTP-TS -forming GDCs had self-renewal ability and possessed certain multipotency. However, they significantly less expressed SOX1 FOXG1 and TUBB3, whereas they expressed LGALS1 significantly higher than normal neural stem/progenitor cells. In addition, we found that LTP-TS -forming GDCs shared the same genetic profiles with original patients’ tumors. Furthermore, we investigated the genetic differences between the glioma tissues which were successfully established as LTP-TS -forming GDCs and those which were not. We found that glioma tissues with TERT promotor mutations and triple CNA (EGFR, CDKN2A, and PTEN loci) are significantly established as LTP-TS -forming GDCs. Lastly, we next investigated in vivo characteristics of glioma PDXs. We have injected glioma PDXs lines into immunodeficient mice and histopathologically analyzed the characteristics of xenografts. Each xenograft well recapitulated histological features of original patients’ tumors and tumor cells remarkably invade through subventricular zone. In conclusion, each LTP-TS -forming GDCs and PDXs had various gene expression profiles, reflecting intratumoral and interpatient heterogeneities of glioma. In addition, TERT promotor mutations and triple CNA significantly correlated with success rate of LTP-TS -forming GDCs. These findings will be of use and advance the preclinical and translational researches of glioma.

Postsynaptic structure formation of human iPS cell-derived neurons takes longer than presynaptic formation during neural differentiation in vitro

The generation of mature synaptic structures using neurons differentiated from human-induced pluripotent stem cells (hiPSC-neurons) is expected to be applied to physiological studies of synapses in human cells and to pathological studies of diseases that cause abnormal synaptic function. Although it has been reported that synapses themselves change from an immature to a mature state as neurons mature, there are few reports that clearly show when and how human stem cell-derived neurons change to mature synaptic structures. This study was designed to elucidate the synapse formation process of hiPSC-neurons. We propagated hiPSC-derived neural progenitor cells (hiPSC-NPCs) that expressed localized markers of the ventral hindbrain as neurospheres by dual SMAD inhibition and then differentiated them into hiPSC-neurons in vitro. After 49 days of in vitro differentiation, hiPSC-neurons significantly expressed pre- and postsynaptic markers at both the transcript and protein levels. However, the expression of postsynaptic markers was lower than in normal human or normal rat brain tissues, and immunostaining analysis showed that it was relatively modest and was lower than that of presynaptic markers and that its localization in synaptic structures was insufficient. Neurophysiological analysis using a microelectrode array also revealed that no synaptic activity was generated on hiPSC-neurons at 49 days of differentiation. Analysis of subtype markers by immunostaining revealed that most hiPSC-neurons expressed vesicular glutamate transporter 2 (VGLUT2). The presence or absence of NGF, which is required for the survival of cholinergic neurons, had no effect on their cell fractionation. These results suggest that during the synaptogenesis of hiPSC-neurons, the formation of presynaptic structures is not the only requirement for the formation of postsynaptic structures and that the mRNA expression of postsynaptic markers does not correlate with the formation of their mature structures. Technically, we also confirmed a certain level of robustness and reproducibility of our neuronal differentiation method in a multicenter setting, which will be helpful for future research. Synapse formation with mature postsynaptic structures will remain an interesting issue for stem cell-derived neurons, and the present method can be used to obtain early and stable quality neuronal cultures from hiPSC-NPCs.

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.

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 IIβ 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 IIβ (TOP2β) as a possible regulator for neuronal differentiation in medulloblastomas and examined the pathological roles of GLI3, NM, GFAP, and TOP2β 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 TOP2β 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 TOP2β-IR was frequently observed only in NM +/GFAP-  medulloblastomas. In fluorescent immunostaining, TOP2β-IR was mostly co-localized with NeuN-IR but not with GFAP-IR. In single-cell RNA sequencing, TOP2β 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.

Alpha-synuclein dynamics in induced pluripotent stem cell-derived dopaminergic neurons from a Parkinson's disease patient (PARK4) with SNCA triplication

Parkinson's disease (PD) is a neurodegenerative disorder caused by the selective loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). Lewy bodies (LBs), another histological hallmark of PD, are observed in patients with familial or sporadic PD. The therapeutic potential of reducing the accumulation of α‐synuclein, a major LB component, has been investigated, but it remains unknown whether the formation of LBs results in the loss of DA neurons. PARK4 patients exhibit multiplication of the α‐synuclein gene (SNCA) without any pathological mutations, but their symptoms develop relatively early. Therefore, study of PARK4 might help elucidate the mechanism of α‐synuclein aggregation. In this study, we investigated the dynamics of α‐synuclein during the early stage of immature DA neurons, which were differentiated from human‐induced pluripotent stem cells (hiPSCs) derived from either a PARK4 patient with SNCA triplication or a healthy donor. We observed increased α‐synuclein accumulation in PARK4 hiPSC‐derived DA neurons relative to those derived from healthy donor hiPSCs. Interestingly, α‐synuclein accumulation disappeared over time in the PARK4 patient‐derived DA neurons. Moreover, an SNCA‐specific antisense oligonucleotide could reduce α‐synuclein levels during the accumulation stage. These observations may help reveal the mechanisms that regulate α‐synuclein levels, which may consequently be useful in the development of new therapies for patients with sporadic or familial PD.

LGG-38. GENETIC ANALYSIS OF NEUROEPITHELIAL TUMORS IN THE PEDIATRIC AND ADOLESCENT AND YOUNG ADULT AGE IN A SINGLE INSTITUTE

Molecular diagnosis in brain tumors has been widely spread after the publication of WHO 2016 classification. But it become a major problem that there are some tumors not to be classified on its criteria, especially in pediatric neuroepithelial tumors. To clarify the characteristics of gliomas in pediatric and adolescent and young adult age (AYA), we picked up 131 neuroepithelial tumors under 30-year-old at Kyoto University and analyze their molecular profiles. Hot spot mutations in IDH1/2, H3F3A, HIST1H3B, TERT promoter, and BRAF were analyzed by Sanger sequencing, and 1p/19q codeletion was examined by FISH or MLPA. With the pathohistological diagnosis and genetic information, all tumors were classified based on WHO 2016 classification. The terms “not otherwise specified” (NOS) and “not elsewhere classified” (NEC) were used based on cIMPACT-NOW. There were 25 glioblastomas and 34 pilocytic astrocytomas, which accounted for a larger percentage than in adult tumors. IDH-wild type gliomas accounted for 55% in diffuse astrocytomas and 69% in anaplastic astrocytomas. The percentages of gliomas with NEC were 50% of oligodendrogliomas and 20% in anaplastic oligodendrogliomas, respectively. Most pilocytic astrocytomas were under 20-year-old (27 patients) and located in infratentorial area (21 patients). Based on WHO 2016 classification, not a few neuroepithelial tumors in pediatric and AYA ages could be classified clearly. These tumors had more different genetic abnormalities than those in adult. Therefore, it may be important to evaluate these tumors with comprehensive genetic analysis.

MBRS-38. MOLECULAR CLASSIFICATION AND CLINICAL CHARACTERISTICS OF 236 MEDULLOBLASTOMAS IN JAPAN

Recent intensive genomic and molecular biological analyses have made a consensus that medulloblastomas (MBs) are at least classified into four core subgroups, and the new 2016 WHO brain tumor classification has introduced the classification of MBs genetically defined in addition to classical histopathological diagnosis. To establish a nationwide network of a molecular diagnosis system for pediatric brain tumors, the JPMNG co-organized by the Japan Society for Neuro-Oncology and the Japanese Society for Pediatric Neurosurgery have started the clinical researches in 2012, and we have summarized results of molecular analysis of Japanese MBs. Total 236 primary MBs have been subclassified by gene expression profile using the NanoString nCounter system or DNA methylation array, and their single nucleotide mutations and copy number aberrations have been also examined. Mean follow up time was 68.9 months. Proportion of four core subgroups were WNT (16.9%), SHH (25.4%), Group 3 (17.4%) and Group 4 (40.3%), respectively. In cases of less than 3 years old, no WNT have been found and 63.2% cases were SHH. In cases between 3 to 17 years old, Group 4 is the most (47%), and these trends is almost consistent with published references. TP53 mutations were identified in 23.3% of SHH, and they were significantly poor prognosis. Metastatic or MYC gain Group 3 MBs were poor prognosis, while Group 4 MBs with loss of chromosome 11 or whole chromosomal aberration were good prognosis. These findings reveal molecular properties of Japanese MBs and will contribute to develop new therapeutic strategies.

MPC-02 Prognostic effects of molecular factors in elderly patients with IDH-wildtype Glioblastomas

BACKGROUND: Geriatric neuro-oncology is an important research field, because the elderly patients is growing at a very rapid rate. This study investigates molecular features and their prognostic effects in the elderly glioblastomas (GBM). METHODS: We collected adult cases diagnosed with IDH-wildtype GBM and enrolled in Kansai Molecular Diagnosis Network for CNS Tumors (212 cases). Clinical and molecular features were analyzed retrospectively and independent prognostic factors were identified statistically. Focusing on the elderly (&gt;=70 years) cases, the association between molecular factors and overall survivals (OS) was examined. RESULTS: Included in the study were 92 elderly cases (43.4%) and median OS was 12.8 months. MGMT promoter was methylated in 50 (54.3%). Triple CNA (EGFR amplification/gain & PTEN deletion & CDKN2A deletion) was detected in 23 (25.0%). NFKBIA was deleted in 23 (25.0%). In the elderly cases, adjuvant radiation and temozolomide (RT+TMZ) was performed in 39 (42.4%) (mOS = 17.1 months). Statistical analyses of the elderly plus non-elderly cases treated with RT+TMZ (148 cases), MGMT promoter, triple CNA and NFKBIA were identified as independent molecular prognostic factors. In the elderly group, however, there was no significant difference in OS according to MGMT status (methylated = 18.7 vs. unmethylated = 17.1, p = 0.3885) or triple CNA status (triple = 13.6 vs. non-triple = 19.6, p = 0.1734). On the other hand, statistical difference was observed according to NFKBIA status (del = 12.1 vs. non-del = 18.7, p = 0.0157*) even in the elderly cases. CONCLUSION: Prognostic effects of molecular factors might be attenuated in the elderly patients. Further investigation in a larger population is necessary.

NI-13 The effectiveness and limitation of survival prediction in primary glioblastoma using machine learning-based texture analysis

Introduction: Clinical application of survival prediction of primary glioblastoma (pGBM) using preoperative images remains challenging due to a lack of robustness and standardization of the method. This research focused on validating a machine learning-based texture analysis model for this purpose using internal and external cohorts. Method: We included all cases of IDH wild-type pGBM available of preoperative MRI (T1WI, T2WI, and Gd-T1WI) from the databases of Kansai Molecular Diagnosis Network for CNS tumors (KN) and The Cancer Genome Atlas (TCGA). Of 242 cases from KN, we assigned 137 cases as a training dataset (D1), and the remaining 105 cases as an internal validation dataset (D2). Furthermore, we extracted 96 cases from TCGA as an external validation dataset (D3). Preoperative MRI scans were semi-quantitatively analyzed, leading to the acquisition of 489 texture features as explanatory variables. Dichotomous overall survival (OS) with a 16.6 months cutoff was regarded as the response variable (short/long OS). We employed Lasso regression for feature selection, and a survival prediction model constructed for D1 via cross-validation (M1) was applied to D2 and D3 to ensure the model robustness. Results: The population of predicted short OS by M1 significantly showed poorer prognosis in D2 (median OS 11.1 vs. 19.4 months; log-rank test, p=0.03), while there was no significant difference in D3 (median OS 14.2 vs. 11.9 months; p=0.61). In the comparative analysis using t-SNE, there was little variation in the feature distribution among three datasets. Conclusion: We were able to validate the prediction model in the internal but not in the external cohort. The presented result supports the use of machine learning-based texture analysis for survival prediction of pGBM in a localized population or country. However, further consideration is required to achieve a universal prediction model for pGBM, irrespective of regional difference.

TERT promoter mutation confers favorable prognosis regardless of 1p/19q status in adult diffuse gliomas with IDH1/2 mutations

TERT promoter mutations are commonly associated with 1p/19q codeletion in IDH-mutated gliomas. However, whether these mutations have an impact on patient survival independent of 1p/19q codeletion is unknown. In this study, we investigated the impact of TERT promoter mutations on survival in IDH-mutated glioma cases. Detailed clinical information and molecular status data were collected for a cohort of 560 adult patients with IDH-mutated gliomas. Among these patients, 279 had both TERT promoter mutation and 1p/19q codeletion, while 30 had either TERT promoter mutation (n = 24) or 1p/19q codeletion (n = 6) alone. A univariable Cox proportional hazard analysis for survival using clinical and genetic factors indicated that a Karnofsky performance status score (KPS) of 90 or 100, WHO grade II or III, TERT promoter mutation, 1p/19q codeletion, radiation therapy, and extent of resection (90-100%) were associated with favorable prognosis (p < 0.05). A multivariable Cox regression model revealed that TERT promoter mutation had a significantly favorable prognostic impact (hazard ratio = 0.421, p = 0.049), while 1p/19q codeletion did not have a significant impact (hazard ratio = 0.648, p = 0.349). Analyses incorporating patient clinical and genetic information were further conducted to identify subgroups showing the favorable prognostic impact of TERT promoter mutation. Among the grade II-III glioma patients with a KPS score of 90 or 100, those with IDH-TERT co-mutation and intact 1p/19q (n = 17) showed significantly longer survival than those with IDH mutation, wild-type TERT, and intact 1p/19q (n = 185) (5-year overall survival, 94% and 77%, respectively; p = 0.032). Our results demonstrate that TERT promoter mutation predicts favorable prognosis independent of 1p/19q codeletion in IDH-mutated gliomas. Combined with its adverse effect on survival among IDH-wild glioma cases, the bivalent prognostic impact of TERT promoter mutation may help further refine the molecular diagnosis and prognostication of diffuse gliomas.

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, O⁶-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.

The association between 11C-methionine uptake, IDH gene mutation, and MGMT promoter methylation in patients with grade II and III gliomas

AIM

To evaluate the association between ¹¹C-methionine positron-emission tomography (¹¹C-methionine PET) findings, isocitrate dehydrogenase (IDH) gene mutation, and O⁶-methylguanine-DNA methyltransferase (MGMT) promoter methylation in patients with grade II and III gliomas.

MATERIALS AND METHODS

Data were collected from 40 patients with grade II and III gliomas who underwent both magnetic resonance imaging (MRI) and ¹¹C-methionine PET as part of their pre-surgical examination. IDH mutation was examined via DNA sequencing, and MGMT promoter methylation via quantitative methylation-specific polymerase chain reaction (PCR).

RESULTS

A threshold of MGMT promoter methylation of 1% was significantly associated with tumour/normal tissue (T/N) ratio. The T/N ratio in samples with MGMT promoter methylation ≥1% was higher than that in samples with MGMT promoter methylation <1%, and the difference was statistically significant (p=0.011). Reliable prediction of MGMT promoter methylation (<1% versus ≥1%) was possible using the T/N ratio under the receiver operator characteristic (ROC) curve with a sensitivity and specificity of 75% each (cut-off value=1.6: p=0.0226, area under the ROC curve [AUC]=0.76172). Conversely, the T/N ratio had no association with IDH mutation (p=0.6). The ROC curve revealed no reliable prediction of IDH mutation using the T/N ratio (p=0.606, AUC=0.60577).

CONCLUSION

¹¹C-methionine PET parameters can predict MGMT promoter methylation but not IDH mutation status. ¹¹C-methionine uptake may have limited potential to reflect DNA methylation processes in grade II and III gliomas.

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.

ACT-10 TREATMENT FOR GLIOBLASTOMA RECURRED AFTER CONCOMITANT CHEMORADIATION THERAPY WITH TEMOZOLOMIDE AND THEIR PROGNOSIS

There are few data about treatment for glioblastoma recurred after concomitant chemoradiation therapy with temozolomide (TMZ). We retrospectively examined treatment and prognosis of recurred glioblastoma patients who registered Kansai molecular diagnosis network for central nervous system tumors, and whose clinical information were available. One hundred and fifty-seven patients that were clinically diagnosed as recurrence between November 2007 and April 2019 were included. Their median age at primary diagnosis was 52 years old and median KPS was 80%. Proportion of methylated MGMT promoter was 43.3% (65 patients), and mutated IDH was 5.4% (8 patients). Median overall survival after recurrence (mSAR) was 8.2 months. One hundred and sixteen patients (73.9%) were received any anticancer treatment and their mSAR was 10.5m. Combination of TMZ and bevacizumab (Bev) were most frequently used for 33 patients, followed by Bev monotherapy for 17 patients, surgery + TMZ + Bev for 15 patients, surgery + TMZ for 12 patients, and TMZ monotherapy for ten. Their mSAR were 8.0m, 7.5m, 10.5m, 13.0m, and 8.0m, respectively. Using univariate analysis, MGMT promoter methylation (p=0.0007), TMZ (p=0.00933), surgery (p=0.0126), re-radiation (p=0.0367), and surgery+TMZ+Bev (p=0.0493) significantly affected prognosis. By multivariate analysis, MGMT promoter methylation, TMZ, and re-radiation were statistically significant (p=0.000138, 0.00161, 0.00403, respectively). These data showed that relatively young patients with good performance status would receive anti-cancer treatment beyond progression and MGMT promoter methylation might be one of prognostic factor for longer survival. In this cohort, re-radiation was performed for few patients and nitrosourea such as nimustine was almost not used. Further study would be needed whether these treatments have any positive effect or not.

TB-08 PATIENT DERIVED XENOGRAFT’S BIOBANK FROM KANSAI MOLECULAR DIAGNOSIS NETWORK FOR CENTRAL NERVOUS SYSTEM TUMORS

Patient-derived xenografts (PDXs) are essential tools for translational research for brain tumors. However, it is sometimes difficult for each institution to establish PDXs because it needs experiences and techniques and it also takes a lot of works to establish them. Thus we aim to establish patient derived xenograft’s biobank among institutions of Kansai Molecular Diagnosis Network for Central Nervous System (CNS) Tumors, Osaka, Japan. We have already began sharing two anaplastic astrocytoma PDXs, twelve glioblastoma IDH wild type PDXs, two medulloblastoma Shh subgroup PDXs, one atypical teratoid/rhabdoid tumor (AT/RT) PDX, and three metastatic brain tumor PDXs. Furthermore these PDXs can also be cultured in vitro, except 2 medulloblastoma SHH subgroup PDXs, 1 AT/RT PDX. However, we have not yet established any PDXs from low grade glioma, ependymoma, primary central nervous system lymphoma (PCNSL), diffuse intrinsic pontine glioma (DIPG).

We began sharing these PDXs among the institutions of Kansai Molecular Diagnosis Network for CNS Tumors, Osaka, Japan. However, further improvement is necessary to succeed in establishing PDX from low grade glioma, PCSNL, DIPG, etc. and get enough number of PDXs so we can share PDXs from almost all of the brain tumors.

NI-02 THE ASSOCIATION BETWEEN 11C-METHIONINE UPTAKE, IDH GENE MUTATION, AND MGMT PROMOTER METHYLATION IN PATIENTS WITH GRADE II AND III GLIOMAS

AIM

We evaluated the association between ¹¹C-methionine positron emission tomography (¹¹C-methionine PET) findings, isocitrate dehydrogenase (IDH) gene mutation, and O⁶-methylguanine-DNA methyltransferase (MGMT) promoter methylation in patients with grade II and III gliomas.

MATERIALS AND METHODS

Data were collected from 40 patients with grade II and III gliomas who underwent both magnetic resonance imaging (MRI) and ¹¹C-methionine positron emission tomography (PET) as part of their pre-surgical examination. We examined IDH mutation through DNA sequencing, and MGMT promoter methylation through quantitative methylation-specific polymerase chain reaction (PCR).

RESULTS

A threshold of MGMT promoter methylation of 1.0% was significantly associated with tumor/normal tissue (T/N) ratio. The T/N ratio in samples with MGMT promoter methylation ≥1.0% was higher than that in samples with MGMT promoter methylation <1.0%, and the difference was statistically significant (p = 0.011). Reliable prediction of MGMT promoter methylation (<1.0% vs ≥1.0%) was possible using the T/N ratio under the receiver operator characteristic (ROC) curve with a sensitivity and specificity of 75% each (cut-off value = 1.6) (p = 0.0226, AUC = 0.76172). Conversely, the T/N ratio had no association with IDH mutation (p = 0.6). The ROC curve revealed no reliable prediction of IDH mutation using the T/N ratio (p = 0.606, AUC = 0.60577).

CONCLUSION

¹¹C-methionine PET parameters can predict MGMT promoter methylation but not IDH mutation status. ¹¹C-methionine uptake may have limited potential to reflect DNA methylation processes in grade II and III gliomas.

NI-13 PREDICTION OF PROGNOSIS IN NEWLY DIAGNOSED GLIOBLASTOMA USING MACHINE LEARNING-BASED TEXTURE ANALYSIS OF PREOPERATIVE MRI

INTRODUCTION

Preoperative magnetic resonance imaging (MRI) is a critical modality for the determination of glioblastoma (GBM) treatment strategy, as it is thought to reflect the biology of the tumor to some extent. The authors attempted to predict prognosis of newly diagnosed GBM (nGBM) using machine learning-based texture analysis of preoperative MRI in this study.

METHOD

A total of 160 nGBMs with determined overall survival were collected from Kansai Molecular Diagnosis Network for CNS tumors. Preoperative MRI scans (T1WI, T2WI, and Gd-T1WI) from all cases were semi-quantitatively analyzed leading to acquisition of 489 texture features as explanatory variables using Matlab-based in-house software. Dichotomous overall survival (OS) with a cutoff of 15 months was regarded as the response variable (short or long OS). Lasso regression was employed for feature selection to ensure robustness of the prediction model. One hundred patients were randomly assigned as training dataset (TR), followed by predictive model construction via 5-fold cross-validation. Subsequently, the constructed model was transferred to the remaining 60 patients, which was assigned as test dataset (TD). The survival distribution between populations with predicted short and long OS was compared using log-rank test.

RESULTS

Distributions of the analyzed data were as follows; 53 short OS cases in the TR (53.0%) and 27 cases in the TD (45.0%). As for the result of transfer analysis in TD, 38 cases out of 60 (63.3%) were predicted to be short OS (76.3 % of recall, 54.3% of precision, and 63.5% of F-measure). The population of predicted short OS significantly showed poorer prognosis (median OS 14.0 vs 19.1 months) (p=0.02, log-rank test).

CONCLUSION

Short OS was successfully identified from preoperative MRI with high recall rates with our algorithm. The presented result ensures the potential of machine learning-based texture analysis for prognostic stratification of nGBM.

PATH-37. PROGNOSTIC ROLE OF TERT PROMOTER MUTATIONS IMPROVES THE STRATIFICATION OF IDH-MUTATED LOWER GRADE GLIOMA

TERT promoter mutation is associated with 1p/19q codeletion and favorable prognosis in IDH-mutated gliomas. Prognostic and diagnostic significance of TERT promoter mutation is well-recognized in IDH-wildtype glioblastomas, but not in IDH-mutated gliomas. We investigated prognostic efficacy of TERT mutation in a cohort of 560 Japanese IDH-mutated adult gliomas. The molecular status of IDH, TERT and 1p/19q and patient clinical data including Karnofsky performance status (KPS) were collected in all cases. TERT mutations and 1p/19q codeletions were found in 303 and 285 cases, respectively. The patient cohort was divided into four groups by a combination of the 1p/19q and TERT status. The characteristics of 1p/19q intact-TERT mutated group (Astro-TERT group, n=24) were compared with those of 1p/19q intact-TERT wild (Astro-group, n=251) or 1p/19q codeleted-TERT mutated (Oligo-group, n=279) cases. Astro-TERT group with any grade showed intermediate overall survival between the Oligo-group and Astro-group although the survival differences were not statistically significant (median overall survival (OS) not reached (NR) versus NR, and 106 months, respectively. p >0.05). We further conducted subgroup analysis by adjusting KPS and WHO grade as Cox regression analysis for survival indicated the unfavorable survival impact of KPS < 90 and WHO grade IV. In the subgroup with favorable KPS (90–100) and grade II-III (n=438), The OS of Astro-TERT group (median NR) was significantly longer survival than that of Astro-group (median 120.2 months, p=0.032), and was comparable with that of the Oligo-group (median NR, p >0.05). On the other hand, OS of none of the molecular groups significantly differ in poorer KPS subgroups (p >0.05). In grade IV tumors, the OS of the Astro-TERT group (NR) was comparable with that of Astro-group (29 months, p=0.19) rather than Oligo-group (NR, p=0.051). Thus, TERT promoter status provides a valuable prognostic information for IDH-mutated grade II-III gliomas in the current molecular diagnostic system.

TMOD-01. CHARACTERIZATION OF PATIENT-DERIVED PRIMARY CELL LINES AND XENOGRAFTS FOR GLIOBLASTOMA

Patient-derived primary cell culture and xenograft are essential tools for translational research for glioblastoma. However, characteristics of each patient derived cell line and xenograft is not extensively studied. In this study, we aim to analyze the characteristics of our glioblastoma patient-derived cell lines and xenografts based on cell surface markers and their differentiation patterns. We have established 20 glioblastoma primary cell culture lines by serum free medium containing EGF and bFGF and found that primary cell culture lines could be classified based on the expression of CD133 and CD44. Four cell lines had high expression of both CD133 and CD44. Eleven cell lines had high expression of only CD44, three cell lines had high expression of only CD133, two cell lines had low expression of both CD133 and CD44. In addition when we induce differentiation, these cell lines showed differentiation to both glial and neuronal differentiation, but differentiation patterns were different depending on each cell line. Four cell lines showed predominant neuronal differentiation and others showed predominant glial differentiation. We next investigated in vivo characteristics of glioblastoma patient derived xenografts from these established cell lines. We have injected these cell lines into NOD/Shi-scid IL2Rγ KO mouse and histopathologically analyzed characteristics of xenografts. Each xenograft well recapitulated histological features of original patients’ tumors and tumor cells remarkably invade through subventricular zone. These results suggest that glioblastoma patient derived primary cell lines and xenografts have different characteristics of cell surface marker expressions and differentiation patterns, thus can classify these cell lines depending on cell surface marker expressions and differentiation patterns. Further analysis is needed to examine the biological importance of the differences in cell surface marker expressions and differentiation patterns.

PATH-02. A COMBINATION OF MGMT METHYLATION AND NFKBIA COPY NUMBER ALTERATION REFINES PROGNOSTICATION OF IDH-WT GLIOBLASTOMAS

INTRODUCTION

Recent studies have reported that NFKBIA deletion (dNFKBIA) was potentially associated with worse prognosis in glioblastoma (GBM) patients. However, no consensus has been reached to its universal prognostic value. Here, we investigated the survival impact of dNFKBIA using two primary IDH wild-type GBM cohorts: an original Japanese cohort and a dataset from The Cancer Genome Atlas (TCGA). Additionally, prognostic impact of a combination of NFKBIA copy number and MGMT methylation status was evaluated.

METHOD

The Japanese cohort was collected from cases registered in Kansai Molecular Diagnosis Network for CNS tumors (KNBTG). The survival impact of dNFKBIA and/or unmethylated MGMT (uMGMT) were analyzed for 212 KNBTG cases and 265 TCGA cases. The hazard ratio (HR) and p-value were computed using Cox regression analysis.

RESULTS

dNFKBIA was less frequently observed in KNBTG (47 cases, 22.2%) than in TCGA (84 cases, 31.7%). dNFKBIA was associated with unfavorable prognosis in KNBTG (HR 1.52, p = 0.031), while this was not validated in TCGA (HR 1.14, p=0.406). uMGMT was a common adverse prognostic factor in KNBGT (HR 1.72, p = 0.001) and TCGA (HR 1.50, p = 0.008) cohort. When stratified by NFKBIA status, uMGMT was also associated with shorter survival in NFKBIA deleted cases both in KNBTG (HR 1.87, p = 0.002) and TCGA (HR 1.59, p = 0.014). On the other hand, MGMT status was not significantly associated with prognosis in NFKBIA intact cases in either KNBTG (HR 1.45, p = 0.279) or TCGA (HR 1.55, p = 0.131).

DISCUSSION

Although the prognostic value of dNFKBIA in IDH wild-type GBM patients was not validated in TCGA cohort, our results indicated that the prognostication based on MGMT methylation was potentially interacted by NFKBIA status.

DDIS-30. EVALUATION OF THE SUSCEPTIBILITY OF NEURONS DERIVED FROM HUMAN INDUCED PLURIPOTENT STEM CELLS TO ANTICANCER DRUGS FOR CNS TUMORS

Various chemical substances, including pharmaceuticals, pose potential risks of inducing acute or delayed neurotoxicity in adults and causing developmental neurotoxicity in fetuses or children. To ensure the safety of chemical substances and drugs, neurotoxicity risk assessment is critical, and an appropriate evaluation platform for neurotoxicity is desired. At present, several anticancer reagents, including temozolomide, cisplatin, and etoposide, are used for treatment of high-grade astrocytic tumors or medulloblastomas. In comparison to lots of information about anti-tumor cells effects of these reagents, their neurotoxicity to normal neurons, especially human derived cells, have been poorly investigated because of the low accessibility of human central nervous system (CNS) tissues, the technical difficulties related to neuron isolation from adult human CNS tissues, and the higher ethical controversy surrounding the use of human CNS tissues and/or fetal cells compared to animal tissues or cells. In this study, to overcome these issues, we made human induced pluripotent stem cells derived neurons (hiPSC-neurons) for preparing alternative assay for in vitro test using primary human neuronal cells, and evaluated their susceptibility to six commonly used anticancer drugs (temozolomide, nimustine, cisplatin, etoposide, mercaptopurine, and methotrexate). Human iPSC-neurons were differentiated using 5-week monolayer culture from hiPSC-derived neural stem/progenitor cells (hiPSC-NSPCs) established by combination the dual SMAD inhibition method with neurosphere culture. In vitro cytotoxic effects of six drugs on hiPSC-neurons and their parental hiPSC-NSPCs were evaluated by ATP assay and immunocytostaining. The hiPSC-neurons were generally more resistant to the anticancer drugs than hiPSC-NSPCs, although a high dose of cisplatin decreased the levels of the neuronal marker protein ELAVL3/4 in the hiPSC-neurons after a 48-h drug treatment. These results suggest that our methodology is potentially applicable for efficient determination of the toxicity of any drug to hiPSC-neurons.

Evaluation of the susceptibility of neurons and neural stem/progenitor cells derived from human induced pluripotent stem cells to anticancer drugs

Various chemicals, including pharmaceuticals, can induce acute or delayed neurotoxicity in humans. Because isolation of human primary neurons is extremely difficult, toxicity tests for these agents have been performed using in vivo or in vitro models. Human induced pluripotent stem cells (hiPSCs) can be used to establish hiPSC-derived neural stem/progenitor cells (hiPSC-NSPCs), which can then be used to obtain hiPSC-neurons. In this study, we differentiated hiPSC-NSPCs into neurons and evaluated the susceptibility of hiPSC-neurons and parental hiPSC-NSPCs to anticancer drugs in vitro by ATP assay and immunocytostaining. The hiPSC-neurons were more resistant to anticancer drugs than the parental hiPSC-NSPCs. In the toxicity tests, high-dose cisplatin reduced the levels of ELAVL3/4, a neuronal marker, in the hiPSC-neurons. These results suggest that our methodology is potentially applicable for efficient determination of the toxicity of any drug to hiPSC-neurons.

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.

Human Genomic Safe Harbors and the Suicide Gene-Based Safeguard System for iPSC-Based Cell Therapy

The use of human induced pluripotent stem cells (hiPSCs) and recent advances in cell engineering have opened new prospects for cell‐based therapy. However, there are concerns that must be addressed prior to their broad clinical applications and a major concern is tumorigenicity. Suicide gene approaches could eliminate wayward tumor‐initiating cells even after cell transplantation, but their efficacy remains controversial. Another concern is the safety of genome editing. Our knowledge of human genomic safe harbors (GSHs) is still insufficient, making it difficult to predict the influence of gene integration on nearby genes. Here, we showed the topological architecture of human GSH candidates, AAVS1, CCR5, human ROSA26, and an extragenic GSH locus on chromosome 1 (Chr1‐eGSH). Chr1‐eGSH permitted robust transgene expression, but a 2 Mb‐distant gene within the same topologically associated domain showed aberrant expression. Although knockin iPSCs carrying the suicide gene, herpes simplex virus thymidine kinase (HSV‐TK), were sufficiently sensitive to ganciclovir in vitro, the resulting teratomas showed varying degrees of resistance to the drug in vivo. Our findings suggest that the Chr1‐eGSH is not suitable for therapeutic gene integration and highlight that topological analysis could facilitate exploration of human GSHs for regenerative medicine applications. Our data indicate that the HSV‐TK/ganciclovir suicide gene approach alone may be not an adequate safeguard against the risk of teratoma, and suggest that the combination of several distinct approaches could reduce the risks associated with cell therapy. stem cells translational medicine2019;8:627&638

Significance of molecular classification of ependymomas: C11orf95-RELA fusion-negative supratentorial ependymomas are a heterogeneous group of tumors

Extensive molecular analyses of ependymal tumors have revealed that supratentorial and posterior fossa ependymomas have distinct molecular profiles and are likely to be different diseases. The presence of C11orf95-RELA fusion genes in a subset of supratentorial ependymomas (ST-EPN) indicated the existence of molecular subgroups. However, the pathogenesis of RELA fusion-negative ependymomas remains elusive. To investigate the molecular pathogenesis of these tumors and validate the molecular classification of ependymal tumors, we conducted thorough molecular analyses of 113 locally diagnosed ependymal tumors from 107 patients in the Japan Pediatric Molecular Neuro-Oncology Group. All tumors were histopathologically reviewed and 12 tumors were re-classified as non-ependymomas. A combination of RT-PCR, FISH, and RNA sequencing identified RELA fusion in 19 of 29 histologically verified ST-EPN cases, whereas another case was diagnosed as ependymoma RELA fusion-positive via the methylation classifier (68.9%). Among the 9 RELA fusion-negative ST-EPN cases, either the YAP1 fusion, BCOR tandem duplication, EP300-BCORL1 fusion, or FOXO1-STK24 fusion was detected in single cases. Methylation classification did not identify a consistent molecular class within this group. Genome-wide methylation profiling successfully sub-classified posterior fossa ependymoma (PF-EPN) into PF-EPN-A (PFA) and PF-EPN-B (PFB). A multivariate analysis using Cox regression confirmed that PFA was the sole molecular marker which was independently associated with patient survival. A clinically applicable pyrosequencing assay was developed to determine the PFB subgroup with 100% specificity using the methylation status of 3 genes, CRIP1, DRD4 and LBX2. Our results emphasized the significance of molecular classification in the diagnosis of ependymomas. RELA fusion-negative ST-EPN appear to be a heterogeneous group of tumors that do not fall into any of the existing molecular subgroups and are unlikely to form a single category.

Lesion location implemented magnetic resonance imaging radiomics for predicting IDH and TERT promoter mutations in grade II/III gliomas

Molecular biological characterization of tumors has become a pivotal procedure for glioma patient care. The aim of this study is to build conventional MRI-based radiomics model to predict genetic alterations within grade II/III gliomas attempting to implement lesion location information in the model to improve diagnostic accuracy. One-hundred and ninety-nine grade II/III gliomas patients were enrolled. Three molecular subtypes were identified: IDH1/2-mutant, IDH1/2-mutant with TERT promoter mutation, and IDH-wild type. A total of 109 radiomics features from 169 MRI datasets and location information from 199 datasets were extracted. Prediction modeling for genetic alteration was trained via LASSO regression for 111 datasets and validated by the remaining 58 datasets. IDH mutation was detected with an accuracy of 0.82 for the training set and 0.83 for the validation set without lesion location information. Diagnostic accuracy improved to 0.85 for the training set and 0.87 for the validation set when lesion location information was implemented. Diagnostic accuracy for predicting 3 molecular subtypes of grade II/III gliomas was 0.74 for the training set and 0.56 for the validation set with lesion location information implemented. Conventional MRI-based radiomics is one of the most promising strategies that may lead to a non-invasive diagnostic technique for molecular characterization of grade II/III gliomas.

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.

Electronic supplementary material

The online version of this article (10.1007/s11060-018-2957-7) contains supplementary material, which is available to authorized users.

Stereotactic image-based histological analysis reveals a correlation between 11C-methionine uptake and MGMT promoter methylation in non-enhancing gliomas

Gliomas are genetically and histopathologically heterogeneous. Intratumoral heterogeneity in the MGMT promoter methylation status is an important clinical biomarker of glioblastoma. A higher uptake of ¹¹C-methionine in positron-emission tomography (PET) reportedly reflects increased MGMT promoter methylation; however, non-stereotactic comparison of MGMT methylation and ¹¹C-methionine PET images may not be accurate. The present study examined the correlation between ¹¹C-methionine uptake and MGMT promoter methylation in non-enhancing gliomas using stereotactic image-based histological analysis. Data were collected from 9 patients with newly diagnosed non-enhancing glioma who underwent magnetic resonance imaging and ¹¹C-methionine PET during pre-surgical examination. Clinical data were also collected from 3 patients during repeat surgery. The correlation between ¹¹C-methionine uptake and MGMT methylation or cell density was analyzed using histological specimens obtained by multiple stereotactic sampling and an exact local comparison of ¹¹C-methionine PET images and histological specimens was made. A total of 31 stereotactic sample sites were identified. In newly diagnosed cases, the tumor to normal uptake (T/N) ratio revealed a significant positive correlation with MGMT methylation (R=0.54, P=0.009) and a marginal correlation with cell density (R=0.42, P=0.05). In recurrent cases, the T/N ratio demonstrated no correlation with MGMT methylation (R=0.01, P=0.97) or cell density (R=0.15, P=0.70). An increased uptake of ¹¹C-methionine in PET may reflect increased MGMT promoter methylation according to stereotactic image-based histological analysis. ¹¹C-methionine PET could therefore be a useful tool for detecting regional MGMT promoter methylation in non-enhancing primary glioma.

Small-scale screening of anticancer drugs acting specifically on neural stem/progenitor cells derived from human-induced pluripotent stem cells using a time-course cytotoxicity test

Since the development of human-induced pluripotent stem cells (hiPSCs), various types of hiPSC-derived cells have been established for regenerative medicine and drug development. Neural stem/progenitor cells (NSPCs) derived from hiPSCs (hiPSC-NSPCs) have shown benefits for regenerative therapy of the central nervous system. However, owing to their intrinsic proliferative potential, therapies using transplanted hiPSC-NSPCs carry an inherent risk of undesired growth in vivo. Therefore, it is important to find cytotoxic drugs that can specifically target overproliferative transplanted hiPSC-NSPCs without damaging the intrinsic in vivo stem-cell system. Here, we examined the chemosensitivity of hiPSC-NSPCs and human neural tissue—derived NSPCs (hN-NSPCs) to the general anticancer drugs cisplatin, etoposide, mercaptopurine, and methotrexate. A time-course analysis of neurospheres in a microsphere array identified cisplatin and etoposide as fast-acting drugs, and mercaptopurine and methotrexate as slow-acting drugs. Notably, the slow-acting drugs were eventually cytotoxic to hiPSC-NSPCs but not to hN-NSPCs, a phenomenon not evident in the conventional endpoint assay on day 2 of treatment. Our results indicate that slow-acting drugs can distinguish hiPSC-NSPCs from hN-NSPCs and may provide an effective backup safety measure in stem-cell transplant therapies.