BRAF p.V600E-mutant gliomas and glioneuronal tumors comprise a wide clinicopathological spectrum, yet the relationship between genomic alteration burden and histological grade remains incompletely defined. We analyzed 15 BRAF p.V600E-mutant gliomas and glioneuronal tumors across histological grades using the PleSSision Rapid sequencing platform. Single-nucleotide variants (SNVs) and copy-number alterations were assessed in parallel to characterize genomic alteration profiles. Low-grade tumors generally exhibited limited genomic alterations; however, a subset of low-grade tumors showed increased numbers of SNVs. High-grade tumors demonstrated more extensive genomic alterations, characterized predominantly by copy-number gains. A trend toward increased copy-number gains with higher WHO grade was observed. Homozygous deletion of CDKN2A was observed in pleomorphic xanthoastrocytoma, including both CNS WHO grade 2 and grade 3 tumors, and epithelioid glioblastoma. These findings indicate substantial genomic heterogeneity among BRAF p.V600E-mutant gliomas and glioneuronal tumors. While low-grade tumors are generally genomically quiet, a subset shows increased alterations, and high-grade tumors tend to acquire copy-number changes, highlighting the limitations of genomic event counts alone as a surrogate for malignant potential.

Abstract Objective To evaluate clinical outcomes of pediatric cases with diffuse intrinsic pontine glioma (DIPG) treated at our institution and to analyze significance of endoscopic third ventriculostomy (ETV) in patients who developed hydrocephalus during clinical course. Background DIPG is a highly aggressive pediatric brain tumor with extremely poor prognosis. Previous studies reported that 15–60% of DIPG patients exhibit hydrocephalus within approximately 5 months after diagnosis, often further compromising quality of life. We aggressively perform endoscopic ETV for DIPG cases exhibiting suspected obstructive hydrocephalus based on MRI images. Methods We retrospectively reviewed the medical records of 27 consecutive pediatric patients with DIPG treated at our institution between January 2010 and December 2025. Demographic and clinical data, imaging findings, treatment details (including radiotherapy, biopsy, and CSF diversion), and outcomes were analyzed. Results The median age at diagnosis was 6 years (range, 2–13 years), and 8 patients (30%) were male. Stereotactic biopsy was performed in 3 patients (11%). All patients received initial radiotherapy with a planned dose of 54 Gy in 30 fractions, which was discontinued in 1 patient due to intratumoral hemorrhage. The median progression-free survival and overall survival were 5.6 and 11.7 months, respectively. Ventricular enlargement was found in 17 patients (68%) during the clinical course. Among them, we performed endoscopic ETV for 9 patients who developed symptoms associated with acute increasement of intracranial pressure (headache and vomiting in 6, impaired consciousness in 3) without significant ETV-related complications. All 9 patients showed rapid postoperative improvement of symptom. Among these 9 patients, for 6 patients (67%), ETV was performed within 3 months after initial diagnosis. No patients required subsequent permanent shunt placement. The median overall survival after ETV was 6.9 months. Conclusions The prognosis of DIPG remains dismal in the modern treatment era. For patients who developed ventricular enlargement at an early phase, ETV might be a safe and effective option for preservation of favorable quality of life during the remaining clinical course by preventing critical intracranial hypertension.

This study evaluated the feasibility of perampanel (PER) monotherapy for perioperative seizure management in patients undergoing awake craniotomy (AC) for glioma, with emphasis on preventing intraoperative intractable seizures. A retrospective analysis was conducted on patients who underwent AC at our institution between December 2024 and December 2025 and received PER monotherapy. PER was administered preoperatively at 2–4 mg. On the day of surgery, an additional 2 mg of PER was given intravenously at the start of the procedure and another 2 mg upon completion. Of 29 patients who underwent AC, five were excluded (four on multiple antiseizure medications and one who declined PER treatment), leaving 24 for analysis. Intraoperative seizures occurred in 3 patients (12.5

Inhibitors of mutant isocitrate dehydrogenase 1 and 2 (IDH) reduce the oncometabolite D-2-hydroxyglutarate (D2-HG) and have demonstrated clinical efficacy in IDH-mutant glioma, but objective response rates remain relatively low, suggesting that IDH inhibition alone may be insufficient for some tumors. To identify therapeutic vulnerabilities under IDH inhibition, we performed a genome-wide CRISPR/Cas9 screen in an IDH-mutant glioma cell line treated with the mutant IDH inhibitor safusidenib. Candidate genes were validated using genetic knockdown and pharmacologic inhibition across multiple IDH-mutant glioma cell lines, with confirmation using the FDA-approved IDH inhibitor vorasidenib. Transcriptomic profiling, cleavage under targets and tagmentation (CUT&Tag), and functional assays were conducted to elucidate the mechanisms underlying combination effects. Mutant IDH inhibition increased H4K20 monomethylation (H4K20me1) levels in IDH-mutant glioma cells. CRISPR/Cas9 screening identified lysine methyltransferase 5A (KMT5A) as a synthetic-lethal target in this context. Combined inhibition of mutant IDH and KMT5A selectively suppressed IDH-mutant glioma cell growth, inducing cell-cycle arrest and apoptosis. Transcriptomic interaction analysis revealed consistent suppression of oxidative phosphorylation and downregulation of ATP6V0E2 and NDUFB9, which encode an H(+)-ATPase subunit and a mitochondrial complex I component, respectively. Functionally, the combination impaired lysosomal acidification, resulting in the accumulation of undegraded proteins, while heightened sensitivity to complex I inhibition reflected a metabolic vulnerability intrinsic to IDH-mutant glioma. These findings demonstrate that combined inhibition of mutant IDH and KMT5A induces synthetic lethality by disrupting lysosomal and mitochondrial homeostasis, leading to apoptotic cell death, and provide a rationale for improving therapeutic efficacy in aggressive IDH-mutant gliomas.

While the efficacy of chemoradiotherapy for intracranial germ cell tumors is established, recent approaches focus on reducing late complications and optimizing treatment intensity by lowering radiation doses and intensifying chemotherapy. From 1978 to 2014, our institution treated germ cell tumors (excluding yolk sac tumor and choriocarcinoma) with carboplatin (CBDCA) and etoposide (VP-16) plus 30 Gy whole ventricular irradiation, achieving 5-year PFS rates of 91.4% for germinoma and 77.2% for non-germinoma, and OS rates of 97.1% and 78.9%, respectively. Since 2014, we reduced radiation to 25.2 Gy and added ifosfamide (IFO) to CBDCA+VP-16 to further reduce late complications. This study retrospectively evaluated outcomes of this new protocol. We retrospectively analyzed 41 patients with newly diagnosed primary intracranial germ cell tumors from April 2014 to August 2022: 24 germinomas, 13 intermediate prognosis non-germinomas, and 4 poor prognosis (yolk sac tumor/choriocarcinoma). All underwent surgery followed by IFO+CBDCA+VP-16 chemotherapy and radiotherapy. Germinoma/intermediate prognosis groups received 25.2 Gy whole ventricular (or whole brain for basal ganglia tumors) irradiation; poor prognosis group received 30.6 Gy craniospinal irradiation. Local boosts were added as needed. The 5-year PFS was 95.8% for germinoma, 84.6% for intermediate prognosis, and 75.0% for poor prognosis groups. All groups had a 5-year OS of 100%. Grade 3 or higher hematologic toxicity occurred in 75.6%, but no treatment-related deaths. Myelosuppression was enhanced after radiotherapy but manageable in all cases. These findings suggest that reducing radiation while intensifying chemotherapy with IFO may improve survival and reduce late adverse effects.

Isocitrate dehydrogenase 1 (IDH1) mutant gliomas are typically diagnosed as low-grade tumors with relatively slow progression. However, many of these tumors inevitably undergo malignant transformation, becoming highly aggressive and resistant to current therapies. While small-molecule inhibitors targeting mutant IDH1 have shown clinical efficacy in some low-grade gliomas, their therapeutic impact in high-grade gliomas remains suboptimal, underscoring the need for new treatment strategies. In this study, we sought to identify novel vulnerabilities in IDH1 mutant gliomas that could be exploited to overcome resistance to mutant IDH1 inhibitors. We conducted a genome-wide CRISPR/Cas9 knockout screening in IDH1 mutant glioma cell lines treated with a mutant IDH1 inhibitor. This approach uncovered multiple candidate genes whose loss induced synthetic lethality in the presence of IDH1 inhibition, particularly genes involved in cell cycle regulation and survival signaling. Although monotherapy with the IDH1 inhibitor successfully reduced intracellular D-2-hydroxyglutarate levels, it exhibited only limited effects on cell proliferation. In contrast, combination treatment with the IDH1 inhibitor and small-molecule inhibitors targeting selected synthetic lethal genes led to marked synergistic antitumor effects, including robust induction of apoptosis. These results were consistently observed in two independent IDH1 mutant glioma cell lines, suggesting potential generalizability of the strategy. We are currently investigating the underlying molecular mechanisms driving this synergy, including changes in epigenetic landscapes and chromatin accessibility, to better understand the biological consequences of combination therapy. Our findings propose a promising therapeutic strategy that targets the adaptive resistance mechanisms of IDH1 mutant gliomas through synthetic lethality. This approach may pave the way for precision medicine tailored to the specific vulnerabilities of malignant IDH1 mutant gliomas and provide new avenues to improve outcomes for patients with treatment-refractory disease.

BACKGROUND:The 5th edition of the World Health Organization Classification of Tumors of the CNS introduced a subclassification of tumors based on key molecular markers. In adult-type diffuse gliomas, isocitrate dehydrogenase (IDH) and telomerase reverse transcriptase (TERT) promoter mutations play pivotal roles in the molecular classification. This study developed a rapid genotyping system using GeneSoC, a real-time PCR platform with microfluidic thermal cycling capable of completing 50 cycles of PCR within 20 min. METHODS:To establish optimal analytical conditions, frozen tumor tissues from 67 patients and artificial DNA vectors were analyzed using this system. This system demonstrated a detection limit of at least 5% variant allele frequency for the IDH1 R132H and TERT promoter C228T/C250T mutations. Subsequently, intraoperative testing was performed in 120 cases using this system. RESULTS:The sensitivity and specificity of IDH1 R132H mutation were 0.985 and 0.982, respectively, whereas those of TERT promoter C228T/C250T mutation were 1.000 and 1.000, respectively. These mutations were detected intraoperatively within approximately 25 min after tumor tissue collection. Furthermore, this assay identified tumor boundaries in an IDH-mutated glioma case, where IDH1 R132H mutations could not be detected. CONCLUSIONS:The GeneSoC®︎-based rapid genotyping system may be effective not only for intraoperative diagnosis of diffuse glioma but also for detecting tumor boundaries.

CNS WHO grade 2 diffuse gliomas with IDH mutations (IDHmut-LGGs) typically exhibit indolent growth but carry a substantial risk of malignant transformation (MT). In this study, we developed and validated a simplified mathematical model to estimate both the timing and likelihood of MT using only pre- and postoperative tumor volumes. This model represents a refinement of our prior approach, which relied on longitudinal MRI data and estimated cumulative tumor burden via trapezoidal integration. In contrast, the new model calculates cumulative tumor volume as the integral of an exponential growth function, enabling accurate MT risk estimation from minimal imaging data. We applied the model to a multi-institutional cohort of 269 patients with IDHmut-LGGs (118 oligodendrogliomas and 151 astrocytomas lacking contrast enhancement on MRI) from 10 centers across Japan. The MT risk predictions generated by the simplified model demonstrated high concordance with those of the previous serial-volume model, with Pearson correlation coefficients of 0.94 for oligodendrogliomas and 0.86 for astrocytomas, and significantly outperformed a time-based model (p < 0.01). Quantitative estimates revealed that, in oligodendrogliomas, the 5-year cumulative MT risk without surgical resection was approximately 41%, whereas reducing tumor volume to 5 cm³ postoperatively reduced the risk to 4.6%. Similarly, in astrocytomas, the corresponding risk decreased from 86% to 14% with comparable volume reduction. Tumor size–based stratification further revealed that lower pre- and postoperative tumor volumes are associated with delayed malignant transformation and improved overall survival (p < 0.05). To promote clinical applicability, we are currently developing a web-based decision-support tool that utilizes pre- and postoperative tumor volumes to estimate MT risk and timing. This platform will enable clinicians to simulate the impact of surgical resection extent, thereby supporting data-driven surgical planning and individualized patient care. Our model offers a practical and robust framework for improving outcome prediction and treatment strategies in IDHmut-LGGs.

The 5th edition of the World Health Organization (WHO) Classification of Tumours of Central Nervous System (CNS) tumours (WHO CNS 5) introduced subclassification of tumors using important molecular markers. In adult-type diffuse gliomas, Isocitrate dehydrogenase (IDH) mutation and telomerase reverse transcriptase (TERT) promoter mutations play pivotal roles in molecular classification. Herein, we aimed to develop a rapid genotyping system using a GeneSoC based on real-time polymerase chain reaction (PCR) with microfluidic thermal cycling, which enables 50-cycles PCR within 20 minutes. To determine analysis condition, we analyzed frozen tumor tissues derived from 67 cases and artificial DNA vector using this system. We could detect at least 5% variant allele frequency of IDH R132H mutation or TERT promoter C228T/C250T mutation. Next, we analyzed 117 cases intra-operatively using this system. After tumor collection we could obtain genotyping of IDH1 R132H for 21.86 minutes or those of TERT C228T/C250T for 24.72 minutes, respectively (n=10). Sensitivity and specificity of IDH1 R132H are 0.979 and 0.984, respectively. Also, those of TERT promoter C228T/C250T are 1.000 and 1.000, respectively. These mutations could be detected within approximately 25 minutes after collection of tumor tissue, intra-operatively. This system is effective for intraoperative diagnosis of astrocytoma, IDH-mutant and oligodendroglioma, IDH-mutant and 1p/19q-codeleted during removal of lower grade diffuse glioma. Also, during removal of diffuse glioma with IDH mutation, we could detect tumor boundary where the IDH1 R132H status turned out to be wild-type, intra-operatively. A rapid genotyping system using GeneSoC might be effective not only for the intra-operative diagnosis of diffuse glioma but also for detection of tumor boundary.

Diffuse hemispheric glioma H3 G34-mutant (DHG) has been identified as a distinct pediatric-type high-grade glioma, according to the World Health Organization (WHO) classification of central nervous system tumors. Widely accepted treatment options include surgery, radiation, and conventional chemotherapy. However, the efficacy of the surgical resection remains unclear. Although there are some reports, a comprehensive understanding of the clinical characteristics, pathogenesis, and outcomes of DHG is insufficient to evaluate the efficacy of maximal tumor resection. We retrospectively analyzed nine cases of DHG, focusing on imaging features and progression patterns. Initial Magnetic Resonance Imaging (MRI) revealed T2/FLAIR high lesions with minimal or no contrast enhancement in all cases. The lesions exhibited T2/FLAIR hyperintensities and focal diffusion restriction in the deep white matter, with most showing high methionine accumulation, suggesting deep white matter infiltration at the time of diagnosis. The extent of white matter infiltration in tumor resection cases was significantly negatively correlated with the extent of resection (EOR). In addition, cases with EOR of 90% or more had significantly longer progression-free survival (PFS) and overall survival (OS). However, achieving an EOR of 90% or more was possible in fewer than half of the cases, primarily in those with relatively limited white matter involvement. Histopathological findings of the tumor obtained by initial resection and autopsy revealed extensive deep white matter infiltration, with one patient demonstrating tumor invasion into the brainstem at death. Our study highlights early deep white matter infiltration of DHGs, complicating surgical resection, and potentially contributing to a poor prognosis. While EOR may influence survival to some extent, residual lesions extensively infiltrate the white matter and eventually invade the brainstem and contralateral brain, thereby contributing to mortality. These findings underscore the challenges of managing DHGs and emphasize the need for further research on effective therapeutic strategies, particularly to understand and target their unique progression patterns.

IDH1-mutant gliomas often undergo malignant transformation over time and progress into treatment-resistant, high-grade tumors. While mutant IDH1 inhibitors have shown some efficacy against lower-grade gliomas, their effects on high-grade gliomas remain limited. Under these circumstances, there is an urgent need to identify novel therapeutic targets from the perspective of synthetic lethality. To identify genes exhibiting synthetic lethality with mutant IDH1 inhibitors, we performed a genome-wide CRISPR/Cas9 screen. Although treatment with the mutant IDH1 inhibitor alone effectively suppressed intracellular D-2-hydroxyglutarate production, it had minimal impact on cell proliferation. Therefore, we aimed to discover gene alterations that could elicit antitumor effects not achievable by monotherapy. The screening identified 176 gene candidates that demonstrated synthetic lethality with the mutant IDH1 inhibitor. Gene Ontology analysis revealed that many of these genes were associated with metabolic pathways. Among them, we focused on KMT5A, a gene involved in amino acid metabolism for which small-molecule inhibitors are already available. Knockdown of KMT5A using siRNA alone did not affect cell proliferation; however, its combination with the mutant IDH1 inhibitor significantly suppressed cell growth. Furthermore, the use of a KMT5A inhibitor in combination therapy led to a marked reduction in cell viability, G0/G1 cell cycle arrest, and induction of late apoptosis. These combinatorial effects were consistently observed across two different cell lines, suggesting potential broad applicability of the strategy. This study successfully identified novel synthetic lethal targets that enhance the efficacy of mutant IDH1 inhibitors in IDH1-mutant gliomas. In particular, combination therapy with KMT5A inhibition emerged as a promising treatment strategy. Ongoing investigations aim to elucidate the underlying molecular mechanisms, including epigenomic alterations. These findings may contribute to the development of precision medicine approaches to overcome resistance to mutant IDH1 inhibitors.

Tumor treating fields (TTFields) treatment has been an important option for the treatment of glioblastoma. The introduction of novel treatment options may lead to distinct recurrence patterns compared to those observed with conventional therapies; however, the specific recurrence pattern during TTFields treatment has not been elucidated. Here, we analyzed 39 cases of glioblastoma treated with TTFields. Although a usage rate of more than 75

BACKGROUND AND PURPOSE:Differentiating between a brain tumor and a nontumorous lesion remains a diagnostic challenge, particularly when conventional imaging modalities such as CT and MRI provide inconclusive results. While 11C-methionine PET (MET-PET) has shown potential in neuro-oncology, its diagnostic performance across a broad spectrum of brain pathologies has not been comprehensively evaluated. This study, therefore, assessed the sensitivity, specificity, and uptake patterns of MET-PET in a large cohort of brain lesions. MATERIALS AND METHODS:This single-center retrospective study analyzed 426 consecutive patients with undiagnosed brain lesions who underwent MET-PET imaging between January 2019 and May 2024. Tumor-to-normal region ratios (TNRs) were calculated by using a threshold of 1.5 for positive findings. Histologic diagnoses were established on the basis of the World Health Organization 2021 criteria, including isocitrate dehydrogenase (IDH) mutation status and 1p/19q-codeletion. RESULTS:Among the cohort, 342 cases (67.8%) were confirmed as having tumorous lesions; 76 (17.8%), as having nontumorous lesions; and 61 (14.3%) remained undiagnosed. MET-PET exhibited high sensitivity (86.2%) but limited specificity (47.4%) for tumor detection. In multiple sclerosis cases, MET-PET showed a remarkably high positivity rate (n = 10/12) that was significantly higher than for other nontumorous lesions. In terms of tumors, IDH wild-type glioblastomas had significantly higher TNRs compared with IDH-mutant gliomas, while oligodendrogliomas had higher TNRs compared with astrocytomas, in which TNR values correlated with tumor grade. CONCLUSIONS:MET-PET demonstrated robust sensitivity for brain tumor detection but was limited by low specificity due to false-positives in inflammatory conditions and false-negatives for low-grade tumors. These findings imply the importance of integrating MET-PET with other imaging modalities to enhance diagnostic accuracy.

IDH-mutant lower-grade gliomas (IDHmut-LGGs) generally exhibit relatively slow progression. However, a significant proportion of cases undergo malignant transformation (MT) within several years, which greatly impacts overall prognosis. We previously developed a mathematical model to estimate the risk and timing of MT based on tumor volume calculated from all available MRI scans during the clinical course (Aoki et al., Cancer Res, 2021). While this model was useful for retrospective analysis, it required longitudinal imaging data and thus had limited applicability in prospective clinical practice. In this study, we developed a simplified mathematical model that dynamically estimates MT risk and timing without the need for serial imaging. The model uses only pre- and postoperative tumor volumes and treatment information as inputs, and assumes exponential tumor growth with treatment-specific growth coefficients. We applied this model to 269 patients with IDHmut-LGGs (118 oligodendrogliomas and 151 astrocytomas) from 10 institutions across Japan. The predicted values showed strong concordance with those of the previous model, with correlation coefficients of 0.94 for oligodendrogliomas and 0.86 for astrocytomas. Furthermore, the model significantly outperformed a simple time-based model (p < 0.01). Using this model, we quantitatively assessed the effect of surgical tumor volume reduction on MT risk in cases with an initial tumor volume of 50 cm3. In oligodendrogliomas, the 5-year MT risk was estimated at 38.52% without resection, which decreased to 9.47% when the postoperative volume was reduced to 10 cm3, and to 6.36% when reduced to 5 cm3. In astrocytomas, the corresponding MT risk was 85.70% without surgery, which decreased to 25.23% and 14.17% with postoperative volumes of 10 cm3 and 5 cm3, respectively. We are currently developing a web-based clinical decision-support tool based on this model, which is expected to assist in prospective treatment planning and optimization of surgical strategies in routine clinical settings.

Li-Fraumeni syndrome (LFS) is an autosomal dominant tumor predisposition syndrome caused by heterozygous germline mutations or deletions in the TP53 tumor suppressor gene. Central nervous system tumors, such as choroid plexus tumors, medulloblastomas, and diffuse gliomas, are frequently found in patients with LFS. Although molecular profiles of diffuse gliomas that develop in pediatric patients with LFS have been elucidated, those in adults are limited. Recently, diffuse gliomas have been divided into pediatric- and adult-type gliomas, based on their distinct molecular profiles. In the present study, we investigated the molecular profiles of high-grade gliomas in three adults with LFS. These tumors revealed characteristic histopathological findings of high-grade glioma or glioblastoma and harbored wild-type IDH1/2 according to whole exome sequencing (WES). However, these tumors did not exhibit the key molecular alterations of glioblastoma, IDH-wildtype such as TERT promoter mutation, EGFR amplification, or chromosome 7 gain and 10 loss. Although WES revealed no other characteristic gene mutations or copy number alterations in high-grade gliomas, such as those in histone H3 genes, PDGFRA amplification was found in all three cases together with uniparental disomy of chromosome 17p, where the TP53 gene is located. DNA methylation analyses revealed that all tumors exhibited DNA methylation profiles similar to those of pediatric-type high-grade glioma H3-wildtype and IDH-wildtype (pHGG H3-/IDH-wt), RTK1 subtype. These data suggest that high-grade gliomas developed in adult patients with LFS may be involved in pHGG H3-/IDH-wt. PDGFRA and homozygous alterations in TP53 may play pivotal roles in the development of this type of glioma in adult patients with LFS.