Automated volumetry of meningiomas in contrast-enhanced T1-Weighted MRI using deep learning

BACKGROUND

Meningiomas are among the most common intracranial tumors. In these tumors, volumetric assessment is not only important for planning therapeutic intervention but also for follow-up examination.However, a highly accurate automated volumetric method for meningiomas using single-modality magnetic resonance imaging (MRI) has not yet been reported. Here, we aimed to develop a deep learning-based automated volumetry method for meningiomas in MRI and investigate its accuracy and potential clinical applications.

METHODS

For deep learning, we used MRI images of patients with meningioma who were referred to Osaka University Hospital between January 2007 and October 2020. Imaging data of eligible patients were divided into three non-overlapping groups: training, validation, and testing. The model was trained and tested using the leave-oneout cross-validation method. Dice index (DI) and root mean squared percentage error (RMSPE) were measured to evaluate the model accuracy. Result: A total of 178 patients (64.6 ± 12.3 years [standard deviation]; 147 women) were evaluated. Comparison of the deep learning model and manual segmentation revealed a mean DI of 0.923 ± 0.051 for tumor lesions. For total tumor volume, RMSPE was 9.5 ± 1.2%, and Mann-Whitney U test did not show a significant difference between manual and algorithm-based measurement of the tumor volume (p = 0.96).

CONCLUSION

The automatic tumor volumetry algorithm developed in this study provides a potential volume-based imaging biomarker for tumor evaluation in the field of neuroradiological imaging, which will contribute to the optimization and personalization of treatment for central nervous system tumors in the near future.

Surgical resection of glioblastoma in basal ganglia and utility of exoscope: Technical case reports

Background

Due to the presence of many perforating arteries and the deep location of basal ganglia tumors, dissection of the perforating arteries is critical during tumor resection. However, this is challenging as these arteries are deeply embedded in the cerebrum. Surgeons need to bend their heads for a long time using operative microscope and it is uncomfortable for the operating surgeon. A high-definition (4K-HD) 3D exoscope system can significantly improve the surgeon's posture during resection and widen the operating view field considerably by adjusting the camera angle.

Methods

We report two cases of glioblastoma (GBM) involving basal ganglia. We used a 4K-HD 3D exoscope system for resecting the tumor and analyzed the intraoperative visualization of the operative fields.

Results

We could approach the deeply located feeding arteries before successfully resecting the tumor using a 4K-HD 3D exoscope system which would have been difficult with the sole use of an operative microscope. The postoperative recoveries were uneventful in both cases. However, postoperative magnetic resonance imaging showed infarction around the caudate head and corona radiata in one of the cases.

Conclusion

This study has highlighted using a 4K-HD 3D exoscope system in dissecting GBM involving basal ganglia. Although postoperative infarction is a risk, we could successfully visualize and dissect the tumors with minimal neurological deficits.

NI-3 FEASIBILITY OF MRI PERFUSION IN DISCRIMINATING BETWEEN EDEMA AND INFILTRATIVE AREAS IN THE PERI-GBM NON-CONTRAST T2 WEIGHTED HIGH AREA

Background

Glioblastomas are highly infiltrative tumors, and differentiating between infiltrating tumors and vasogenic edema occurring in the non-enhancing T2-weighted hyperintense area is challenging. Here, we differentiated between infiltrating tumors and edemas in glioblastomas using dynamic perfusion-weighted MR imaging.

Methods

Data were collected from 33 patients with glioblastomas and 15 with meningioma as controls, who underwent resection at our institution between January 2019 and March 2022. The MRI data included T2 weighted images and contrast-enhanced T1 weighted images, and dynamic perfusion-weighted MR imaging. Two neurosurgeons manually assigned regions of interest (ROIs) to infiltrating tumors and vasogenic edema based on a previous report using conventional MRI features. The ratio of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) in the ROIs to that contralateral normal regions were calculated. We also histological analysis using histological specimens obtained by stereotactic biopsy in each ROI.

Results

CBF and MTT ratios of infiltrating tumors and edemas differed significantly (p<0.01), while CBF and MTT ratios of edemas and controls showed similarities. MTT values of controls and infiltrating tumors differed significantly (p=0.02). Receiver operating characteristic curve analysis revealed that CBF (area under the curve [AUC]=0.81) and MTT(AUC=0.95) were effective in distinguishing between infiltrating tumors and edemas. Pathological analysis revealed that cell density, MIB1-index, and microvessel density were higher in infiltrating tumors than in edemas.

Conclusions

Using dynamic perfusion-weighted MR imaging may prove useful in differentiating infiltrating tumors from edemas in the non-contrast T2 hyperintensity region of glioblastomas.

IM-3 IDENTIFICATION OF THERAPEUTIC TARGET ANTIGENS USING PATIENT DERIVED GLIOBLASTOMA AND THEIR APPLICATION TO CAR-T THERAPY

Introduction

Recently, CAR-T cell (chimertic antigen receptor T-cell) therapy has been attracting and has shown high therapeutic efficacy, especially in the hematological tumors. The T cells from patient are then genetically engineered to specifically bind to and attack the target tumor cell antigen. In the brain, EGFRvIII or HER2 have been used as antigens, but have yet to show positive results. It is necessary to find antibodies that are more specific and have a therapeutic effect.

Methods

A primary culture line was prepared from glioblastoma surgical specimens, and immunized to Balb/c mice with it.The B cells from the mice were fused with myeloma cells, immortalized, and cultured monoclonally to obtain a number of monoclonal antibodies reacted glioblastoma cells. The obtained antibodies were reacted with glioblastoma cells and normal brain cells, and those that specifically react to glioblastoma were selected by flowcytometry to obtain antibody candidates that could be specifically expressed on the surface of glioblastoma cells.

Results

Approximately 20,000 antibody-producing strains were generated. From these, about 3,200 strains were selected as the reacted with immunized glioblastoma. About 560 strains was selected that reacted with at least one other glioblastoma, and from these, we selected 30 strains that did not react with normal brain cells. Finally, the cells were frozen and thawed at least once, and 13 stably growing strains selected.

Discussion

We have been identified one antibody among approximately 500 strains in past our study, and have confirmed that it is B7H3, a pan-tumor antibody. We will generate more antibody candidates in the future, as well as identify antibodies in 13 strains that have already been selected and confirmed to be glioblastoma-specific antibodies. We will also create CAR-T cells targeting these antibodies and confirm their anti-tumor effects.

ACT-20 PHASE 1/2, PROSPECTIVE, INTERNATIONAL MULTI-CENTER STUDY TO ESTABLISH THE SAFETY AND FEASIBILITY OF BLOOD-BRAIN-BARRIER DISRUPTION COMBINED WITH CARBOPLATIN FOR RECURRENT GLIOBLASTOMA; FIRST CLINICAL EXPERIENCE IN JAPAN

The prognosis for glioblastoma is still very poor despite intensive treatment by surgery, radiation, and chemotherapy. One of the reasons for poor prognosis of glioblastoma is blood-brain-barrier (BBB), which limits the delivery of chemotherapeutic agents to the brain. Focused ultrasound (FUS) therapy is approved for essential tremor and Parkinson disease in Japan and preclinical studies suggest low-intensity focused ultrasound (LIFU) administered with microbubbles (MB) can disrupt BBB and can improve the delivery of chemotherapeutic agents. Thus, currently, focused ultrasound therapy has gained attention in neuro-oncology and a number of clinical trials using FUS for the treatment of glioblastoma are underway. Our institutions (Osaka University Hospital and Saito Yukoukai Hospital) are the first in Japan to join the international multicenter study to examine the safety and feasibility of BBB disruption by FUS and MB combined with intravenous carboplatin for the treatment of recurrent glioblastoma. We are planning to enroll one recurrent glioblastoma patient for this study soon. BBB disruption strategies using FUS and MB for the treatment of neuro-oncological disease has potentials to improve the outcome of patients and many clinical trials will be performed in future.

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.

MNG-3 STRATIFICATION OF TUMOR GROWTH BY RISK FACTORS AND PREDICTED TUMOR VOLUME CURVES FOR SUPRATENTORIAL MENINGIOMAS

Background

The natural history of meningiomas is still unclear, and no guidelines have been established based on objective indices regarding the necessity and timing of therapeutic intervention.Objective: We attempted to provide statistics on the characteristics of tumor volume change, stratify tumor growth by risk factors, and generate a predictive tumor volume curve based on the statistics, with the aim of describing the natural history of meningiomas.

Methods

313 cases were included in the study, with the origin of meningioma being the circumflex and parasagittal sinus areas and the cerebral sickle region, and with multiple MRI scans performed at intervals of at least 3 months. Relative growth rate (RGR) and annual volume change (AVC) were calculated by measuring tumor volume, and the patients were classified into three groups according to the combination of gender, age, and MRI T2WI signal intensity, and compared.

Results

The median RGR and AVC of the entire cohort were 6.1% and 0.20 cm3/year, respectively, and there were significant differences between groups in gender (p=0.018) and MRI T2WI (p < 0.001) for RGR and tumor location (p=0.025) and initial tumor volume (p < 0.001)for AVC. The median RGR and AVC in the classification were 17.5% and 1.05 cm3/year for the very high growth group, 8.2% and 0.33 cm3/year for the high growth group, and 3.4% and 0.04 cm3/year for the low growth group, showing significant differences between the groups (p < 0.001). The predicted tumor volume curve showed an average 2.24-fold or 5.24 cm3 increase in volume over 5 years in the very high-growth group, while little tumor volume change was observed in the low-growth group.

Conclusion

The combination of growth risk factors allowed stratification of tumor growth and provided a predictive tumor volume curve for each county. The results may assist in the treatment of meningiomas.

Identification of glioblastoma-specific antigens expressed in patient-derived tumor cells as candidate targets for chimeric antigen receptor T cell therapy

Background

New therapies for glioblastoma (GBM) are urgently needed because the disease prognosis is poor. Chimeric antigen receptor (CAR)-T cell therapy that targets GBM-specific cell surface antigens is a promising therapeutic strategy. However, extensive transcriptome analyses have uncovered few GBM-specific target antigens.

Methods

We established a library of monoclonal antibodies (mAbs) against a tumor cell line derived from a patient with GBM. We identified mAbs that reacted with tumor cell lines from patients with GBM but not with nonmalignant human brain cells. We then detected the antigens they recognized using expression cloning. CAR-T cells derived from a candidate mAb were generated and tested in vitro and in vivo.

Results

We detected 507 mAbs that bound to tumor cell lines from patients with GBM. Among them, E61 and A13 reacted with tumor cell lines from most patients with GBM, but not with nonmalignant human brain cells. We found that B7-H3 was the antigen recognized but E61. CAR-T cells were established using the antigen-recognition domain of E61-secreted cytokines and exerted cytotoxicity in co-culture with tumor cells from patients with GBM.

Conclusions

Cancer-specific targets for CAR-T cells were identified using a mAb library raised against primary GBM tumor cells from a patient. We identified a GBM-specific mAb and its antigen. More mAbs against various GBM samples and novel target antigens are expected to be identified using this strategy.

IMMU-19. IDENTIFICATION OF TARGET ANTIGENS FOR CHIMERIC ANTIGEN RECEPTOR T- CELL THERAPY AGAINST GLIOBLASTOMA USING A MONOCLONAL ANTIBODY LIBRARY RAISED AGAINST PATIENT-DERIVED TUMOR SPHERES

New therapies for GBM are urgently needed due to its poor prognosis and chimeric antigen receptor T (CAR-T) cell therapy is thought to be a promising strategy. To develop CAR-T cell therapy, cell surface targets that is highly specific for GBM cells are needed.Although extensive transcriptome analyses of GBM cells were performed, few transcripts highly specific for GBM cells have been identified. However, GBM cell-specific antigen epitopes formed by post-translational modifications of proteins may have been missed, and could still be discovered by thoroughly searching for cancer-specific monoclonal antibodies and characterizing the antigens they recognize. In this study, we applied this strategy to search for GBM-specific cell surface targets using patient derived tumor spheres. We identified two monoclonal antibodies E61 and A13 as those reacting with GBM cells but not with normal brain parenchymal cells. CAR-T cells derived from both monoclonal antibodies produced IL-2 and IFNɤ and exerted cytotoxicity to GBM cells by chromium 51 release assay. In addition, we identified B7-H3, which is frequently used for a CAR-T cell target against GBM, as the antigen recognized by B7-H3 by the expression cloning method. These results indicate that the strategy shown in this study is useful for identifying antigens that are expressed on patient-derived GBM cells and potentially useful as targets for CAR T cells.

Growth risk classification and typical growth speed of convexity, parasagittal, and falx meningiomas: a retrospective cohort study

OBJECTIVE

Meningiomas are the most common primary intracranial tumors, and their clinical and biological characteristics vary by location. Convexity, parasagittal, and falx meningiomas account for approximately 50%-65% of intracranial meningiomas. Focusing only on these locations, the aim of this study was to determine the typical speed of tumor growth, to assess the growth risk, and to show the possible tumor volume that many lesions can reach after 5 years.

METHODS

Patients with radiologically suspected convexity, parasagittal, or falx meningiomas at the authors' institution were studied retrospectively. The relative growth rate (RGR) and annual volume change (AVC) were calculated from MRI at more than 3-month intervals. Based on sex, age, and signal intensity on T2-weighted MRI, the cases were classified into three groups: extremely high-growth, high-growth, and low-growth groups.

RESULTS

The data of 313 cases were analyzed. The median RGR and AVC for this entire cohort were 6.1% (interquartile range [IQR] 2.4%-16.0%) and 0.20 (IQR 0.04-1.18) cm3/year, respectively. There were significant differences in sex (p = 0.018) and T2-weighted MRI signal intensity (p < 0.001) for RGR, and T2-weighted MRI signal intensity (p < 0.001), tumor location (p = 0.025), and initial tumor volume (p < 0.001) for AVC. The median RGR and AVC were 17.5% (IQR 8.3%-44.1%) and 1.05 (IQR 0.18-3.53) cm3/year, 8.2% (IQR 2.9%-18.6%) and 0.33 (IQR 0.06-1.66) cm3/year, and 3.4% (IQR 1.2%-5.8%) and 0.04 (IQR 0.02-0.21) cm3/year for the extremely high-growth, high-growth, and low-growth groups, respectively, with a significant difference among the groups (p < 0.001). A 2.24-times, or 5.24 cm3, increase in tumor volume over 5 years was typical in the extremely high-growth group, whereas the low-growth group showed little change in tumor volume even over a 5-year follow-up period.

CONCLUSIONS

For the first time, the typical speed of tumor growth was calculated, focusing only on patients with convexity, parasagittal, and falx meningiomas. In addition, the possible tumor volume that many lesions in these locations can reach after 5 years was shown based on objective indicators. These results may allow clinicians to easily detect lesions that require frequent follow-up or early treatment by determining whether they deviate from the typical range of the growth rate, similar to a growth chart for children.

[Utility of Neurosurgical Procedures Using 4K 3D Exoscopes: Clinical Experience with a 4K 3D Exoscope and Review of Literature]

The operating microscope has been an essential tool in neurosurgery since the late 1960s and continues to be a critically important tool for neurosurgical procedures. However, it may be accompanied by flaws since the neurosurgeon's position during surgery is limited. A newly developed surgical microscope, ORBEYE^TM(OLYMPUS, Tokyo, Japan), was launched to overcome the shortcomings of the operative microscope and offers 4 K, high-quality, and three-dimensional(3D)imaging. ORBEYE^TM offers similar visual fidelity but superior ergonomics and educational benefits compared with those of the operating microscope. Exoscopic surgeries maintain the same safety profiles as those using operative microscopes and have the potential to allow neurosurgeons to generalize neurosurgical procedures, which are considered difficult due to the neurosurgeon's awkward positions. This study summarizes the utility of the 4K 3D exoscope, ORBEYE^TM, and presents our experiences with its use in neurosurgical procedures.

Cerebellopontine angle metastasis of a neuroendocrine tumor mimicking vestibular schwannoma: A case report

Background:

Neuroendocrine tumors (NETs) are uncommon neoplasms arising from neuroendocrine cells and are rarely associated with intracranial metastases.

Case Description:

We discuss the case of a 74-year-old woman with a right CPA tumor. She had a history of retroperitoneal NET, but was diagnosed with vestibular schwannoma due to a right-sided hearing loss and a right CPA tumor along the VII and VIII nerves. After a 3-year follow-up, she presented with repetitive vomiting, a 1-month history of gait instability, and a 3-month history of general fatigue. Brain imaging revealed tumor growth and edematous changes in the right cerebellum. She underwent retrosigmoid craniotomy and partial resection. Histopathological examination revealed metastatic NET. She underwent stereotactic radiosurgery for residual lesion and, at 11 months of follow-up, the lesion was confirmed to have shrunk on magnetic resonance imaging (MRI).

Conclusion:

This is the first case to report the natural course of cerebellopontine metastasis of a NET. The differential diagnosis of CPA tumors is diverse, and, in our case, we suspected a vestibular schwannoma because of the typical symptoms and imaging features. However, the tumor grew relatively faster than expected and showed intratumoral hemorrhage during the 3-year follow-up. Therefore, in patients with a history of a NET, a careful follow-up is advisable even for lesions highly suspected to be another benign tumor on MRI. Careful follow-up imaging and appropriate treatment strategies were useful to manage the brain metastasis. Although NETs metastasizing to the CPA are extremely rare, this possibility should be considered when patients with NETs have intracranial lesions.

GCT-21. Long-term outcome and follow up of intracranial germ cell tumors: Reduced-dose radiotherapy and intensified chemotherapy improves clinical outcome and quality of life for long-term survivors

BACKGROUND: Intracranial germ cell tumors (iGCT) are heterogeneous tumors with several histopathology. Chemoradiotherapy is effective and required for treatment against them, but optimal treatment intensity should be selected from the viewpoint of both improvement of clinical outcome and avoidance of late complications. We introduced a protocol with reduced-dose radiotherapy and intensified chemotherapy for iGCT. OBJECTIVE: We retrospectively analysed the clinical outcome, especially for non-germinomatous germ cell tumors and long-term clinical outcome of late complications, enrollment and employment, as indicators of quality of life (QOL). MATERIALS AND METHODS: Thirty-eight children and young adults (28 men and 10 women) with iGCTs treated in our institution from 1997 to 2013 were enrolled in this study. They consisted of 26 germinomas including HCG-producing cases and 12 non-germinomatous GCTs (NGGCT). Local irradiation was selected for all patients, and the dose of irradiation was 23.4-54 Gy. The whole-brain irradiation was made in patients who had intracranial dissemination, but any prophylactic irradiation to the whole brain and spinal cord was not performed. For NGGCT, high-dose chemotherapy and peripheral blood stem cell transplantation (PBSCT) were introduced. Second-look surgeries were performed for cases with residual tumors after induction chemotherapies. RESULTS: In germinoma group and NGGCT group, 10-year progression-free survival was 86% and 84%, 10-year overall survival was 93% and 91%, respectively. About late complications, endocrinological replacement (39%), cerebrovascular disease such as cavernous hemangioma and arterial stenosis (18%), secondary neoplasm (2.6%) were observed. Regarding QOL, enrollment and return to school rate was 92% and employment and the return rate was 89%, which were influenced by hemipararesis associated with basal ganglia lesion, intractable epilepsy and whole-brain irradiation. CONCLUSION: Reduced-dose radiotherapy and intensified chemotherapy for iGCT, especially NGGCT, improved the clinical outcome and QOL of long-term survivors, suppressing late complications. Further comprehensive follow-up and analysis are needed.

Selective targeting of multiple myeloma cells with a monoclonal antibody recognizing the ubiquitous protein CD98 heavy chain

Cancer-specific cell surface antigens are ideal therapeutic targets for monoclonal antibody (mAb)-based therapy. Here, we report that multiple myeloma (MM), an incurable hematological malignancy, can be specifically targeted by an mAb that recognizes a ubiquitously present protein, CD98 heavy chain (hc) (also known as SLC3A2). We screened more than 10,000 mAb clones raised against MM cells and identified R8H283, an mAb that bound MM cells but not normal hematopoietic or nonhematopoietic cells. R8H283 specifically recognized CD98hc. R8H283 did not react with monomers of CD98hc; instead, it bound CD98hc in heterodimers with a CD98 light chain (CD98lc), a complex that functions as an amino acid transporter. CD98 heterodimers were abundant on MM cells and took up amino acids for constitutive production of immunoglobulin. Although CD98 heterodimers were also present on normal leukocytes, R8H283 did not react with them. The glycoforms of CD98hc present on normal leukocytes were distinct from those present on MM cells, which may explain the lack of R8H283 reactivity to normal leukocytes. R8H283 exerted anti-MM effects without damaging normal hematopoietic cells. These findings suggested that R8H283 is a candidate for mAb-based therapies for MM. In addition, our findings showed that a cancer-specific conformational epitope in a ubiquitous protein, which cannot be identified by transcriptome or proteome analyses, can be found by extensive screening of primary human tumor samples.

How Much Tumor Volume Is Responsible for Development of Clinical Symptoms in Patients With Convexity, Parasagittal, and Falx Meningiomas?

Purpose: Meningiomas are the most common primary intracranial neoplasms and clinical symptom appearance depends on their volume and location. This study aimed to identify factors that influence clinical symptoms and to determine a specific threshold tumor volume for the prediction of symptomatic progression in patients with convexity, parasagittal, and falx meningiomas.

Materials and Methods: We retrospectively studied patients with radiologically suspected convexity, parasagittal, or falx meningiomas at our institution.

Results: The data of three hundred thirty-three patients were analyzed. We further divided patients into two groups based on clinical symptoms: an asymptomatic group (250 cases) and a symptomatic group (83 cases). Univariate analysis revealed significant differences between the groups in terms of sex (p = 0.002), age at the time of volumetric analysis (p < 0.001), hyperintense lesions on T2-weighted images (p = 0.029), peritumoral edema (p < 0.001), maximum tumor diameter (p < 0.001), and tumor volume (p < 0.001). Further multivariate analysis revealed significant differences between the groups in terms of age at the time of volumetric analysis (p = 0.002), peritumoral edema (p < 0.001), and tumor volume (p < 0.001). The receiver operating characteristic curve revealed a threshold tumor volume of 21.1 ml for predicting whether a patient would develop symptoms (sensitivity 0.843, specificity 0.880, an area under the curve 0.919 [95% confidence interval: 0.887–0.951]).

Conclusion: We identified factors predictive of clinical symptoms in patients with convexity, parasagittal, and falx meningiomas and determined the first-ever threshold tumor volume for predicting symptomatic progression in such patients.

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.

COT-16 Development of automatic lesion extraction application using artificial intelligence for the purpose of simplifying tumor volume measurement of meningioma

BACKGROUND: With the widespread use of MRI equipment and brain scans, opportunities to perform follow-up examinations for meningiomas have increased. On the other hand, an objective evaluation index for meningiomas characterized by slow changes on imaging has not been established. To establish a volume-based evaluation index for meningoceles, we are developing an application for automatic lesion extraction using artificial intelligence as a highly reproducible tumor volume measurement technique that enables large volume image data processing. METHODS: In this study, 195 patients with meningioma who underwent contrast-enhanced MRI imaging at Osaka University Hospital were included. The images were manually extracted by three neurosurgeons and used as supervised data. deeplabV3 was used as the learning network. All the supervised data were randomly divided into training (80%) and testing (20%) data, and the application was constructed by deep learning and validation with 5-fold cross-validation. The matching rate of the area of the region automatically extracted by the device against the test data and the mean square error rate of the calculated tumor volume were used as indices of the product measurement performance. RESULTS: The matching rate using the automatic extraction application for the correct data(Dice index) was 91.5% on average. The mean squared error rate of the tumor volume calculated from these extracted regions was 8.84%. CONCLUSION: We consider that this application using artificial intelligence has a certain degree of validity in terms of the accuracy of extracted lesions. In the future, it is necessary not only to improve the performance of the equipment but also to clarify the clinical significance of the new imaging biomarkers based on tumor volume that can be obtained from these lesion extraction techniques.

TB-9 An attempt to establish a patient-derived brain tumor culture model by organoid culture method

Background: Molecular heterogeneity among and within tumors are one of the reasons for the poor survival rate of brain tumors even with the current standard therapy. However, monolayer culture and neuro-sphere culture (NS) use exogenous growth factors, so may not show the true nature of the tumor. And the culture establishment rate is low, especially low-grade tumors. Therefore, we used the glioblastoma organoid (GBO) culture method showed by Fadi to create culture models of various brain tumors and investigated their characteristics.

Methods: We examined the establishment rate in pathological and genotypic types of 56 patients who underwent brain tumor resection at our hospital between January 2020 and June 2021 and were cultured with GBO or NS. If tumor cells are increased visually at 1 month after culture, we defined establishment.

Results: There were 15 cases of glioblastoma, 7 cases of anaplastic astrocytoma, 7 cases of diffuse astrocytoma, 3 cases of diffuse midline glioma, 2 cases of anaplastic oligodendroglioma, 5 cases of oligodendroglioma, and 16 cases of others. The establishment rate was 76.5% by the GBO method and 40% by the N S method. By histological type, GBO: 80% in glioblastoma, NS: 58.3% in glioblastoma, GBO: 83.3% in AA, NS: 40% in AA, and GBO: 100% in DA. The IDH mutation and pTERT mutation were investigated in GBO: IDHwt/TERT+ 87.5%, IDHwt/TERT- 64.3%, IDHmt/TERT- 100%, and in NS: IDHwt/TERT+ 75%, IDHwt/TERT- 33.3%, IDHmt/ TERT- 20% in NS. In addition, establishment was observed in GBO 2 case in medulloblastoma, 1 case in ependymoma.

Discussion and Conclusion: This suggest that GBO can be used to establish culture models for low-grade tumors. In addition, GBO can establish culture earlier, so it is expected to be applicable to personalized therapies such as preclinical drug efficacy studies tailored to individual patients.

IM-7 Identification of novel glioblastoma specific antigen using patient derived tumor cell for CAR-T cell therapy

Chimeric antigen receptor T (CAR-T) cell therapy is a newly developed antitumor immunotherapy presenting remarkable clinical response with leukemia, and is expected to be applied to other malignant solid tumors including glioblastoma (GBM). However, for development of CAR-T therapy against GBM, identification of novel and suitable tumor specific antigen is required to expect higher therapeutic efficacy. Herein, we developed our original method to detect novel GBM specific antigen using patient derived GBM (PD-GBM) cells. First, BALB/c mice were immunized by footpad injection of PD-GBM cells. B cells were extracted from lymph nodes of the mice, fused with murine myeloma cells, and then cultured to produce monoclonal antibodies for GBM cells. About 500 GBM binding monoclonal antibody lines were established, and then each antibody was again analyzed by flow cytometry with multiple PD-GBM cells and human non-tumor brain cells to find out GBM specific antibodies. Consequently, two GBM specific antibody lines were selected and genetically analyzed to identify the recognized antigen. CAR-T cells targeting the detected antigens were successfully generated, and the cytotoxicity against GBM cells was confirmed by chromium releasing assay and bioluminescent cytokine assay. Remarkably, one of the identified tumor specific antigens proved to be B7-H3, which is known pan-cancer antigen expected to be one CAR-T therapeutic target for malignant solid tumors, also expressed in most GBM cells. This result confirms that our experimental method using murine antigen-antibody reaction is feasible for detecting antigen as a novel CAR-T therapeutic target for GBM. Moreover, this method can also detect antigens derived from post-translational conformational changes such as glycosylation, which might have been overlooked by conventional methods. In addition, these results suggest our method using PD-GBM cells can identify potential targets of CAR-T therapy for each GBM patients respectively, thus leading to precision immunotherapy for GBM.

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.

Subgroup and subtype-specific outcomes in adult medulloblastoma

Medulloblastoma, a common pediatric malignant central nervous system tumour, represent a small proportion of brain tumours in adults. Previously it has been shown that in adults, Sonic Hedgehog (SHH)-activated tumours predominate, with Wingless-type (WNT) and Group 4 being less common, but molecular risk stratification remains a challenge. We performed an integrated analysis consisting of genome-wide methylation profiling, copy number profiling, somatic nucleotide variants and correlation of clinical variables across a cohort of 191 adult medulloblastoma cases identified through the Medulloblastoma Advanced Genomics International Consortium. We identified 30 WNT, 112 SHH, 6 Group 3, and 41 Group 4 tumours. Patients with SHH tumours were significantly older at diagnosis compared to other subgroups (p < 0.0001). Five-year progression-free survival (PFS) for WNT, SHH, Group 3, and Group 4 tumours was 64.4 (48.0-86.5), 61.9% (51.6-74.2), 80.0% (95% CI 51.6-100.0), and 44.9% (95% CI 28.6-70.7), respectively (p = 0.06). None of the clinical variables (age, sex, metastatic status, extent of resection, chemotherapy, radiotherapy) were associated with subgroup-specific PFS. Survival among patients with SHH tumours was significantly worse for cases with chromosome 3p loss (HR 2.9, 95% CI 1.1-7.6; p = 0.02), chromosome 10q loss (HR 4.6, 95% CI 2.3-9.4; p < 0.0001), chromosome 17p loss (HR 2.3, 95% CI 1.1-4.8; p = 0.02), and PTCH1 mutations (HR 2.6, 95% CI 1.1-6.2; p = 0.04). The prognostic significance of 3p loss and 10q loss persisted in multivariable regression models. For Group 4 tumours, chromosome 8 loss was strongly associated with improved survival, which was validated in a non-overlapping cohort (combined cohort HR 0.2, 95% CI 0.1-0.7; p = 0.007). Unlike in pediatric medulloblastoma, whole chromosome 11 loss in Group 4 and chromosome 14q loss in SHH was not associated with improved survival, where MYCN, GLI2 and MYC amplification were rare. In sum, we report unique subgroup-specific cytogenetic features of adult medulloblastoma, which are distinct from those in younger patients, and correlate with survival disparities. Our findings suggest that clinical trials that incorporate new strategies tailored to high-risk adult medulloblastoma patients are urgently needed.

Utility of a novel exoscope, ORBEYE, in gravity-assisted brain retraction surgery for midline lesions of the brain

Background

Midline brain lesions, such as falx meningioma, arteriovenous malformations, and cavernous malformations, are usually approached from the ipsilateral interhemispheric fissure. To this end, patients are positioned laterally with the ipsilateral side up. However, some studies have reported the usefulness of gravity-assisted brain retraction surgery, in which patients are placed laterally with the ipsilateral side down or up, enabling surgeons to approach the lesions through the ipsilateral side or through a contralateral interhemispheric fissure, respectively. This surgery requires less brain retraction. However, when using an operative microscope, performing this surgery requires the surgeon to operate in an awkward position. A recently developed high-definition (4K-HD) 3-D exoscope system, ORBEYE, can improve the surgeon's posture while performing gravity-assisted brain retraction surgery.

Methods

We report five cases with midline brain tumors managed by resectioning with gravity-assisted brain retraction surgery using ORBEYE. We also performed an ergonomic analysis of gravity-assisted brain retraction surgery with a craniotomy model and a neuronavigation system.

Results

Gravity-assisted brain retraction surgery to the midline brain tumors was successfully performed for all five patients, using ORBEYE, without any postoperative neurological deficit.

Conclusion

Gravity-assisted brain retraction surgery to the midline brain lesions using ORBEYE is feasible, and ORBEYE is ergonomically more favorable than a microscope. ORBEYE has the potential to generalize neurosurgical approaches considered difficult due to the surgeon's awkward position, such as gravity-assisted brain retraction surgery.

Distinct difference in tumor-infiltrating immune cells between Wilms' tumor gene 1 peptide vaccine and anti-programmed cell death-1 antibody therapies

Background

Wilms’ tumor gene 1 (WT1) peptide vaccine and anti-programmed cell death-1 (anti-PD-1) antibody are expected as immunotherapies to improve the clinical outcome of glioblastoma. The aims of this study were to clarify how each immunotherapy affects tumor-infiltrating immune cells (TIIs) and to determine whether the combination of these two therapies could synergistically work.

Methods

Mice were transplanted with WT1 and programmed cell death-ligand 1 doubly expressing glioblastoma cells into brain followed by treatment with WT1 peptide vaccine, anti-PD-1 antibody, or the combination of the two, and survival of each therapy was compared. CD45⁺ cells were positively selected as TIIs from the brains with tumors, and TIIs were compared between WT1 peptide vaccine and anti-PD-1 antibody therapies.

Results

Most mice seemed to be cured by the combination therapy with WT1 peptide vaccine and anti-PD-1 antibody, which was much better survival than each monotherapy. A large number of CD4⁺ T cells, CD8⁺ T cells, and NK cells including WT1-specific CD8⁺ and CD4⁺ T cells infiltrated into the glioblastoma in WT1 peptide vaccine-treated mice. On the other hand, the number of TIIs did not increase, but instead PD-1 molecule expression was decreased on the majority of the tumor-infiltrating CD8⁺ T cells in the anti-PD-1 antibody-treated mice.

Conclusion

Our results clearly demonstrated that WT1 peptide vaccine and anti-PD-1 antibody therapies worked in the different steps of cancer-immunity cycle and that the combination of the two therapies could work synergistically against glioblastoma.

Necessity for craniospinal irradiation of germinoma with positive cytology without spinal lesion on MR imaging-A controversy

Background

Cerebrospinal fluid (CSF) cytology and spinal MR imaging are routinely performed for staging before treatment of intracranial germinoma. However, the interpretation of the results of CSF cytology poses 2 unresolved clinical questions: (1) Does positive CSF cytology correlate with the presence of spinal lesion before treatment? and (2) Is craniospinal irradiation (CSI) necessary for patients with positive CSF cytology in the absence of spinal lesion?

Methods

Multicenter retrospective analyses were performed based on a questionnaire on clinical features, spinal MR imaging finding, results of CSF cytology, treatments, and outcomes which was sent to 86 neurosurgical and 35 pediatrics departments in Japan. Pretreatment frequencies of spinal lesion on MR imaging were compared between the patients with positive and negative cytology. Progression-free survival (PFS) rates were compared between patients with positive CSF cytology without spinal lesion on MR imaging treated with CSI and with whole brain or whole ventricular irradiation (non-CSI).

Results

A total of 92 germinoma patients from 45 institutes were evaluated by both CSF cytology and spinal MR images, but 26 patients were excluded because of tumor markers, the timing of CSF sampling or incomplete estimation of spinal lesion. Of the remaining 66 germinoma patients, spinal lesions were equally identified in patients with negative CSF cytology and positive cytology (4.9% and 8.0%, respectively). Eleven patients treated with non-CSI had excellent PFS comparable to 11 patients treated with CSI.

Conclusion

CSI is unnecessary for germinoma patients with positive CSF cytology without spinal lesions on MR imaging.

So-called bifocal tumors with diabetes insipidus and negative tumor markers: are they all germinoma?

BACKGROUND

The Delphi consensus statements on the management of germ cell tumors (GCTs) failed to reach agreements on the statement that the cases with (i) pineal and neurohypophyseal bifocal lesion, (ii) with diabetes insipidus, and (iii) with negative tumor markers can be diagnosed as germinoma without histological verification. To answer this, multicenter retrospective analysis was performed.

METHODS

A questionnaire on clinical findings, histological diagnosis, and details of surgical procedures was sent to 86 neurosurgical and 35 pediatrics departments in Japan.

RESULTS

Fifty-one institutes reported 132 cases that fulfilled the 3 criteria. Tissue sampling was performed in 91 cases from pineal (n = 44), neurohypophyseal (n = 32), both (n = 6), and distant (n = 9) lesions. Histological diagnosis was established in 89 cases: pure germinoma or germinoma with syncytiotrophoblastic giant cells in 82 (92.1%) cases, germinoma and mature teratoma in 2 cases, and granulomatous inflammation in 2 cases. Histological diagnosis was not established in 2 cases. Although no tumors other than GCTs were identified, 3 (3.4%) patients had non-germinomatous GCTs (NGGCTs). None of the patients developed permanent complications after endoscopic or stereotactic biopsy. Thirty-nine patients underwent simultaneous procedure for acute hydrocephalus without permanent complications, and hydrocephalus was controlled in 94.9% of them.

CONCLUSION

All patients who fulfilled the 3 criteria had GCTs or granulomatous inflammation, but not other types of tumors. However, no fewer than 3.4% of the patients had NGGCTs. Considering the safety and the effects of simultaneous procedures for acute hydrocephalus, biopsy was recommended in such patients.

Impact of Inversion Time for FLAIR Acquisition on the T2-FLAIR Mismatch Detectability for IDH-Mutant, Non-CODEL Astrocytomas

The current research tested the hypothesis that inversion time (TI) shorter than 2,400 ms under 3T for FLAIR can improve the diagnostic accuracy of the T2-FLAIR mismatch sign for identifying IDHmt, non-CODEL astrocytomas. We prepared three different cohorts; 94 MRI from 76 IDHmt, non-CODEL Lower-grade gliomas (LrGGs), 33 MRI from 31 LrGG under the restriction of FLAIR being acquired with TI < 2,400 ms for 3T or 2,016 ms for 1.5T, and 112 MRI from 112 patients from the TCIA/TCGA dataset for LrGG. The presence or absence of the “T2-FLAIR mismatch sign” was evaluated, and we compared diagnostic accuracies according to TI used for FLAIR acquisition. The T2-FLAIR mismatch sign was more frequently positive when TI was shorter than 2,400 ms under 3T for FLAIR acquisition (p = 0.0009, Fisher’s exact test). The T2-FLAIR mismatch sign was positive only for IDHmt, non-CODEL astrocytomas even if we confined the cohort with FLAIR acquired with shorter TI (p = 0.0001, Fisher’s exact test). TCIA/TCGA dataset validated that the sensitivity, specificity, PPV, and NPV of the T2-FLAIR mismatch sign to identify IDHmt, non-CODEL astrocytomas improved from 31, 90, 79, and 51% to 67, 94, 92, and 74%, respectively and the area under the curve of ROC improved from 0.63 to 0.87 when FLAIR was acquired with shorter TI. We revealed that TI for FLAIR impacts the T2-FLAIR mismatch sign’s diagnostic accuracy and that FLAIR scanned with TI < 2,400 ms in 3T is necessary for LrGG imaging.

Chloride intracellular channel 1 cooperates with potassium channel EAG2 to promote medulloblastoma growth

Ion channels represent a large class of drug targets, but their role in brain cancer is underexplored. Here, we identify that chloride intracellular channel 1 (CLIC1) is overexpressed in human central nervous system malignancies, including medulloblastoma, a common pediatric brain cancer. While global knockout does not overtly affect mouse development, genetic deletion of CLIC1 suppresses medulloblastoma growth in xenograft and genetically engineered mouse models. Mechanistically, CLIC1 enriches to the plasma membrane during mitosis and cooperates with potassium channel EAG2 at lipid rafts to regulate cell volume homeostasis. CLIC1 deficiency is associated with elevation of cell/nuclear volume ratio, uncoupling between RNA biosynthesis and cell size increase, and activation of the p38 MAPK pathway that suppresses proliferation. Concurrent knockdown of CLIC1/EAG2 and their evolutionarily conserved channels synergistically suppressed the growth of human medulloblastoma cells and Drosophila melanogaster brain tumors, respectively. These findings establish CLIC1 as a molecular dependency in rapidly dividing medulloblastoma cells, provide insights into the mechanism by which CLIC1 regulates tumorigenesis, and reveal that targeting CLIC1 and its functionally cooperative potassium channel is a disease-intervention strategy.

GCT-69. VOLUMETRIC CHANGE BEFORE CHEMORADIOTHERAPY AND INFLUENCE OF DIAGNOSTIC RADIATION EXPOSURE IN INTRACRANIAL GERMINOMAS

BACKGROUND

Spontaneous regression in intracranial germ cell tumors has been reported in some literatures, but the mechanism has not been well known. We retrospectively measured the tumor volume before chemoradiotherapy and analyzed factors that influence reduction of tumor volume.

PATIENTS AND METHODS

Plural MRI scans were done before the first course of chemotherapy regimen in 27 patients with primary intracranial germinomas. Their age ranged from 8 to 31 years. 35 lesions from them were enrolled and included 13 pineal, 4 neurohypophyseal, 4 basal ganglia, 4 bifocal type, and 2 multiple lesions. All regions were verified as pure germinoma or HCG-producing germinoma by histopathological examination. Tumor volume of 35 lesions was analyzed by volumetric assessment based on MRI. Ratio of volumetric change between the first MRI and the scan immediately before chemotherapy was defined as shrinking rate (%). Period between disease onset and the first chemotherapy was 20 to 47 days. Diagnostic radiation dose was calculated in each case.

RESULTS

Initial tumor volume ranged from 0.962 to 72.356 cubic centimeters (mean: 8.27). Diagnostic radiation dose: 40.5 to 910.1 mGy. Shrinking rate ranged from -57.8 to 85.4% (mean: 30.8). In 10 regions, shrinking rate was within 30%. Shrinking rate was significant positively influenced by diagnostic radiation dose (p<0.05) and negatively influenced by initial volume (p<0.05). But, other factors such as age, sex, histopathological parameters did not influence tumor shrinkage.

CONCLUSION

This study shows that the volume of intracranial germ cell tumors is changing dynamically before chemoradiotherapy in many cases. Diagnostic exposure to low-dose radiation influences tumor shrinkage of intracranial germinomas.

QOL-44. ASSESSMENT OF NEUROCOGNITIVE FUNCTION AND MRI PARAMETERS IN LONG-TERM SURVIVORS WITH POSTERIOR FOSSA TUMORS: A COMPARISON BETWEEN MEDULLOBLASTOMAS TREATED BY REDUCED-DOSE CRANIOSPINAL IRRADIATION AND OTHER TUMORS

BACKGROUND

Children with medulloblastoma cannot avoid chemoradiotherapy including craniospinal radiation, although prognosis of medulloblastoma has improved and previous studies have reported a significant risk of intellectual disturbance by these treatments. We retrospectively analysed neurocognitive functions, clinical MRI parameters of patients with posterior fossa tumors, especially medulloblastomas.

MATERIALS AND METHODS

Twenty-two patients (12 medulloblastomas, 5 ependymomas, 5 astrocytomas) treated in our institution were enrolled in this study. Mean age was 7.8 years and 6.5 years, percentage of hydrocephalus at onset was 66.7% and 60%, respectively in medulloblastoma group and in other tumor group (ependymoma and astrocytoma). Postoperative chemoradiotherapy including reduced-dose craniospinal irradiation (18Gy) was done for medulloblastoma group and local radiation or operation only was done for other group. Version 3 or 4 of Wechsler Intelligent Scale for Children (WISC) was used by neurocognitive function analysis. Ventricular size, white matter volume and other parameters were also was estimated based on MRI. Follow-up duration was 6–17 years (mean: 10.5 years).

RESULTS

Evaluations of neurocognitive functions based on WISC pointed out lower performance IQ than verbal IQ in long term survivor of both group, especially working memory (P=0.05). Both hydrocephalus and cranial nerve complications was influenced lower scores of WISC, but age at onset did not influence WISC scores. Comparison between both group showed there was no significant difference about cognitive function and white matter volume.

STMO-03 Surgical resection for precentral gyrus glioma

Primary motor cortex glioma is usually considered unresectable because of its high risk for motor deficit. However, recent reports suggest that surgical resection for primary motor cortex brain tumor is feasible for selected patients. In this study, we analyzed the neurological outcomes for 27 patients who underwent surgical resections for precentral gyrus glioma. Glioma grades for 27 patients were Grade II in 6 cases, Grade III in 7 cases, and Grade IV in 13 cases. 11 patients were recurrent glioma cases and glioma grade for those patients were Grade II in 4 cases, Grade III in 3 cases, and Grade IV in 4 cases. Extent of resection for 27 patients was biopsy in 2 cases, partial resection in 16 cases, and more than 90% of resections in 9 cases. 6 patients underwent awake surgery and glioma grade for those patients were Grade II in 3 cases, Grade III in 2 cases, and Grade IV in 1 case. Median extent of resection for patients who underwent awake surgery was 90%. Transient neurological worsening was observed in 5 patients, however, no patient exhibited permanent neurological deficit. Surgical resections for primary motor cortex glioma were feasible in selected patients without severe neurological complication. Careful intraoperative awake mapping is desirable to achieve maximum resections.

ANGI-03 Functional roles of CD166/activated leukocyte cell adhesion molecule (CD166/ALCAM) for glioblastoma invasion

CD166/activated leukocyte cell adhesion molecule (CD166/ALCAM) is a transmembrane receptor, widely expressed in various tissues, and is involved in several functions such as cell adhesion, neurogenesis and angiogenesis. We have previously reported that CD166/ALCAM is expressed on glioblastoma progenitor cells and is involved in glioblastoma invasion. However, we only have analyzed the functional roles of ALCAM using glioblastoma cell lines, not using patient derived xenografts. In this study, we investigated the functional roles of CD166/ALCAM using patient derived xenografts. We established CD166/ALCAM knocked-down glioblastoma patient derived cell lines by shRNA. For in vitro analysis, we seeded control and CD166/ALCAM knocked-down glioblastoma cells on culture dishes and performed time lapse analysis to investigate cell motility. For in vivo analysis, we orthotopically injected control and CD166/ALCAM knocked-down glioblastoma cells into the immunodeficient mice. When the mice got sick due to the tumor, we dissected the mice and analyzed the difference in invasion by immunohistochemical analysis. We found that CD166/ALCAM knocked-down glioblastoma cells significantly decreased cell motility by time lapse analysis. In addition, CD166/ALCAM knocked-down glioblastoma cells suppressed cell invasion and leptomeningeal metastasis by immunohistochemical analysis from patient derived xenografts. Our results suggest that CD166/ALCAM is involved in glioblastoma invasion, thus future studies are necessary to investigate whether CD166/ALCAM could be a therapeutic target for glioblastoma.

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.

COT-18 Prognosis and problems about secondary intracranial neoplasm in childhood cancer survivors: a single-institution retrospective cohort study

Objective: As childhood cancer survivors gradually increased, late complications of treatment have been at issue and risk of secondary neoplasm is increasing cumulatively. We retrospectively analyzed clinical outcome and problems of treatment for secondary intracranial neoplasm. Patients and Methods: 497 patients (children, adolescents and young adults) with malignant central nervous system neoplasm were treated in our institution from 1971 to 2015. 188 cases (37.8%) were enrolled in this follow-up study. Diagnosis of primary neoplasm included low grade glioma (29%), embryonal tumor (23.5%), germ cell tumor (24.5%), ependymoma (8%), other (15%). Results: Fourteen cases of them were diagnosed as secondary intracranial neoplasm. Twelve cases were operated and histopathological diagnosis included 6 glioblastomas, 1 anaplastic astrocytoma, 1 anaplastic ependymoma, 4 meningiomas. In all cases, histopathological finding and molecular profile of secondary intracranial neoplasm differed from that of primary malignant brain tumors. Duration from the first operation of primary tumors to diagnosis of secondary intracranial neoplasm ranged from 5 to 36 years (average: 29.3). In malignant glioma cases except meningioma cases, origin of them was contained in high irradiation field (&gt;40Gy). In malignant glioma cases, Chemotherapies using temozolomide and bevacizumab were selected after tumor removal. In 3 cases of them, reirradiation was performed. Response for treatment was poor or transient in most cases, median survival time was 12 months. Of late complications, such as endocrinological problem needed replacement (55%), cerebrovascular event (15.9%), secondary neoplasm (7.4%), secondary neoplasm was importantly related with prognosis. Conclusion: It is difficult to plan therapeutic strategies against second malignant neoplasm because of lack of information in case of long-term survivors and restriction for first radiation. Clinical outcome of them is poor and new treatment targets should be developed. It is important to plan clinical trials to reduce treatment intensity and usable long-term follow-up system.

Endovascular Treatment for Middle Cerebral Artery Aneurysms: Single-Center Experience and Review of Literatures

Objective

The efficacy of endovascular treatment for middle cerebral artery (MCA) aneurysms remains controversial. However, recent studies have reported the safety of endovascular treatment for MCA aneurysms. In this study, we studied the efficacy and clinical outcomes of endovascular treatment for MCA aneurysms in our hospital and the morphology and anatomy of MCA aneurysms that were suitable for endovascular treatment.

Methods

We retrospectively analyzed 26 cases of MCA aneurysms which had undergone endovascular treatment at our institution between January 2015 and October 2018. We studied sizes and shapes of the aneurysms, clinical and angiographical outcomes one year after the treatment, and complications in these 26 patients. We also compared the differences in these parameters of the 26 patients with those of 61 other patients who were treated with clipping during the same period.

Results

The median aneurysm size was 6.1 mm (1.8-29.9 mm), with the shapes of the aneurysms irregular in 8, and round in the other 18 cases. Four cases (15.4%) had ruptured aneurysms. All aneurysms were treated with assist techniques; 8 (30.8%) were treated by stent-assisted technique and 18 (69.2%) were treated by balloon-assisted technique and endovascular treatment was successfully performed in all (100%) cases. While the aneurysms were completely obliterated in 22 of them (84.6%), the remaining 4 cases (15.4%) had neck remnants. We observed periprocedural complications in 5 of the 26 (19.2%) aneurysms, all of which were transient and completely recovered during the follow-up period. The efficacy and complication rates were not different from the MCA aneurysms treated with clipping. All MCA aneurysms arising from the M1 trunk were treated with endovascular treatment, and those with a round shape with the axis not deviating from M1 were also treated with endovascular treatment.

Conclusion

Endovascular treatment for MCA aneurysms is safe and effective together with adjunctive techniques such as balloon-assisted technique or stent-assisted technique. Thus, M1 trunk aneurysms and MCA bifurcation aneurysms with a round shape along the same axis of MCA may be good indications for endovascular treatment. However, long-term clinical and angiographical outcomes remain unknown. Thus, further studies are needed to address the existing limitations.

CBIO-02. COMPREHENSIVE ANALYSIS OF MECHANISMS AND MOLECULAR TARGETS FOR BREAST CANCER LEPTOMENINGEAL METASTASIS

Leptomeningeal metastasis from solid cancer is a devastating state for cancer patients. Leptomeningeal metastasis is diagnosed either by cerebrospinal fluid cytology and/or magnetic resonance imaging (MRI). However, it remains unclear as to whether tumor cells attached to leptomeninges are the same from floating tumor cells in cerebrospinal fluid (CSF). In this study, we aim to analyze the differences between tumor cells attached to leptomeninges and floating cells in CSF by xenograft models. We used breast cancer cell line, MDA-MB-231, labelled with green fluorescent protein (GFP) and luciferase. We injected those cells into right lateral ventricle of NOD/Shi-scid IL2Rγ KO mice. When the mice got any signs of tumor, we dissected spinal cord and got CSF from mice. We sorted tumor cells by flow cytometry and extracted RNA from the sorted tumor cells from spinal cord and CSF, respectively. We analyzed transcriptome differences between tumor cells from spinal cord and CSF by RNA sequencing. We found that extracellular matrix related proteins were highly upregulated while cell growth related proteins were downregulated in tumor cells from spinal cord compared with those from CSF. These results suggest that tumor cells attached to leptomeninges have different transcriptome profiles from floating tumor cells in CSF and extracellular matrix related proteins could be therapeutic targets for breast cancer leptomeningeal metastasis.

NIMG-11. IMPACT OF INVERSION TIME FOR FLAIR ACQUISITION ON THE T2-FLAIR MISMATCH DETECTABILITY FOR IDH-MUTANT, NON-CODEL ASTROCYTOMAS

PURPOSE

The current research tested the hypothesis that TI shorter than 2400 ms under 3T for FLAIR can improve the diagnostic accuracy of the T2-FLAIR mismatch sign for identifying IDHmt, non-CODEL astrocytomas.

EXPERIMENTAL DESIGN

We prepared three different cohorts; 94 MRI from 76 IDHmt, non-CODEL LrGGs, 33 MRI from 31 LrGG under the restriction of FLAIR being acquired with TI &lt; 2400 ms for 3T or 2016 ms for 1.5T, and 103 MRI from 103 patients from the TCIA/TCGA dataset for LrGG. The presence or absence of the “T2-FLAIR mismatch sign” was evaluated, and we compared diagnostic accuracies according to TI used for FLAIR acquisition.

RESULTS

The T2-FLAIR mismatch sign was more frequently positive when TI was shorter than 2400 ms under 3T for FLAIR acquisition (p = 0.0009, Fisher’s exact test). The T2-FLAIR mismatch sign was positive only for IDHmt, non-CODEL astrocytomas even if we confined the cohort with FLAIR acquired with shorter TI (p = 0.0001, Fisher’s exact test). TCIA/TCGA dataset validated that the sensitivity, specificity, PPV, and NPV of the T2-FLAIR mismatch sign to identify IDHmt, non-CODEL astrocytomas improved from 31%, 90%, 79%, and 51% to 67%, 94%, 92%, and 74%, respectively if we acquired FLAIR with TI shorter than 2400 ms.

CONCLUSIONS

We revealed that TI for FLAIR impacts diagnostic accuracy of the T2-FLAIR mismatch sign and that FLAIR scanned with TI &lt; 2400 ms in 3T is necessary for LrGG imaging.

Surgical Treatment of Brain Metastasis of Extramammary Paget's Disease: A Case Report

Extramammary Paget’s disease (EMPD) is a rare form of neoplasm. Metastasis of EMPD to locations other than lymph nodes and intra-epithelial regions is rare; there are a limited number of case reports of metastases to the liver, lung, bone, and brain. We present a rare case of EMPD that metastasized to the brain and was treated with surgical resection. A 66-year-old man presented with a small palpable mass in the scrotum. After 5 years of observation, he was diagnosed with EMPD that metastasized to the lymph nodes and lung. Tumor resection and postoperative chemotherapy were performed. Six months after the last chemotherapy treatment, he presented with a right temporal lobe tumor and underwent surgical resection. Histopathological analysis revealed brain metastasis of EMPD. Three months after surgery, magnetic resonance imaging (MRI) showed local tumor recurrence, and intensity modulated radiation therapy (IMRT) (45 Gy/15 Fr) was performed. Although the metastatic brain tumor was well controlled, the primary tumor progressed. He was provided best supportive care and died 5 months after brain tumor resection. In this report, we present a rare case of brain metastasis of EMPD, treated with surgical resection, and histopathologically confirmed to be metastatic EMPD.

STMO-10 SURGICAL RESECTION FOR PRIMARY MOTOR CORTEX GLIOMA, TWO CASE REPORTS

Primary motor cortex glioma is usually considered unresectable because of its high risk for motor deficit. However recent reports suggest that surgical resections for primary motor cortex brain tumor is feasible for selected patients. In this case report, we report two cases we can successfully resected primary motor cortex glioma by awake surgery without neurological worsening.

Case1 was 32 year-old woman with right primary motor cortex oligodendroglioma. We could only perform biopsy at initial surgery, however the patient got worsening of left hemiparesis which were gradually improved by rehabilitation. The patient underwent 50 Gy of radiation therapy and 6 courses of PCV chemotherapy. 60 months after the initial surgery, the tumor recurred and the she underwent 12 courses of temozolomide chemotherapy, but tumor continued to grow. She underwent second surgery 13 years after the initial biopsy. We resected primary motor cortex tumor by awake surgery without neurological complication.

Case2 was 31 year-old woman with left primary motor cortex oligodendroglioma. We could only perform biopsy at initial surgery, however the patient got mild right hemiparesis which were improved by rehabilitation. The patient underwent 4 courses of PAV chemotherapy and 54 Gy of Intensity Modulated Radiation Therapy (IMRT). 21 months after IMRT, the tumor recurred and the she underwent second surgery. We resected primary motor cortex tumor by awake motor mapping without severe neurological complication.

In conclusion, surgical resections for primary motor cortex glioma is feasible in selected patients without severe neurological complication. Neural plasticity is the reason for this, but careful intraoperative awake mapping is necessary to achieve maximum resections.

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.

MNG-08 VOLUMETRIC STUDIES IN ASYMPTOMATIC MENINGIOMAS: SLOWDOWN CASES AND GROWTH ARREST CASES

BACKGROUND

The opportunity to follow up for asymptomatic meningiomas has increased. We have reported the risk of volume increase by individual continuous volume measurement of asymptomatic meningiomas. However, We have not reached fully understanding about natural history of meningiomas. Among cases are followed up over time, there are some cases that the volume increase rates slows down or almost stops are observed.

METHODS

We enrolled consecutive adult patients of asymptomatic meningiomas who follow-up for 2 years or more and 3 or more MRI scans. We performed sequential volumetric measurements on 95 patients (105 lesions) who met the criteria. We classified these transient volume curve of each lesion into three groups “Growing”, “Slowdown”, and “Growth arrest” for analysis.

RESULTS

The average age at the first visit was 62.8 years, the average follow-up period was 61.8 months, and the male-female ratio was 20:75 (male: female). There were 67 cases (73 lesions: 70.9%) that were in increasing trend, and 19 cases of those were received resection. Eleven cases (12 lesions: 11.7%) showed a tendency of “slow down” the increase rate, and one patient who became symptomatic led to surgical excision. In 18 cases (18 lesions: 17.4%) in which almost no volume change was observed during the observation period, no cases resulted in surgical treatment.

CONCLUSIONS

Among the meningiomas cases that have been followed for a long time, there are not a few those increase rate of tumor volume slows or does not change. Furthermore, most of these cases did not result in surgical treatment. The presence of these “Slowdown” and “Growth arrest” cases at a certain rate may have suggested the possibility of a Gompertz curve model as the natural course of meningiomas.

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.

IMT-07 CLINICAL TRIAL OF A COCKTAIL WILMS’ TUMOR 1 (WT1) VACCINATION USING TWO HLA CLASS I PEPTIDES AND ONE CLASS II PEPTIDE FOR RECURRENT MALIGNANT GLIOMAS

PURPOSE

Our clinical trials shows the safety and clinical efficacy of Wilms’ tumor 1 (WT1) human leukocyte antigen (HLA) class I (Izumoto S et al. J Neurosurg. 2008) and class II (Tsuboi A et al. Cancer Immunol Immunother. 2019) peptide vaccination for recurrent malignant gliomas have been established. We have developed a cocktail vaccine (WT1 trio) containing two class I peptides (HLA-A*24:02 and HLA-A*02:01) and one II class peptide to improve more effective immunological response and improve patient’s prognosis. Clinical trial of a cocktail vaccination using WT1 HLA class I and II peptides for recurrent malignant gliomas is planned to verify its safety, clinical efficacy and usefulness of surrogate markers.

PATIENTS AND METHODS

Twenty-three patients with recurrent malignant gliomas, which showed WT1-positive in tumor samples and HLA-A*24:02 or HLA-A*02:01-positive in blood sample, were enrolled. These patients (age: 26–72 years old, average: 49.4) included 15 cases of glioblastomas and 8 of anaplastic astrocytomas. Patients received a WT1 trio vaccine intradermally, 7 times at 2-week intervals during 3 months.WT1-DTH and WT1-IgG antibody were regularly measured. Vaccine-related adverse events, best clinical response and the transfer rate of long-term administration of WT1 trio vaccination were estimated.

RESULTS

WT1-DTH positive cases were 12, WT1-IgG antibody positive were in 11. In most patients, WT1 -DTH positiveness coincided with that of WT1-IgG antibody. 9 of 11 cases showed stable disease at 3 months and transferred long-term administration of WT1 trio vaccination. Transfer rate in GBM and AA of long-term administration was 33% and 25%, respectively. Grade1 skin eruption was observed at the injection sites in 15 cases, but no significant adverse events related with vaccination were shown.

CONCLUSION

the safety and clinical efficacy of WT1 trio vaccination was verified for recurrent malignant gliomas. WT1-DTH and WT1-IgG antibody may be useful surrogate markers.

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.

Recurrent noncoding U1 snRNA mutations drive cryptic splicing in SHH medulloblastoma

Recurrent somatic single nucleotide variants (SNVs) in cancer are largely confined to protein coding genes, and are rare in most pediatric cancers^1–3. We report highly recurrent hotspot mutations of U1 spliceosomal small nuclear RNAs (snRNAs) in ~50% of Sonic Hedgehog medulloblastomas (Shh-MB), which were not present across other medulloblastoma subgroups. This U1-snRNA hotspot mutation (r.3a>g), was identified in <0.1% of 2,442 cancers across 36 other tumor types. Largely absent from infant Shh-MB, the mutation occurs in 97% of adults (Shhδ), and 25% of adolescents (Shhα). The U1-snRNA mutation occurs in the 5′ splice site binding region, and snRNA mutant tumors have significantly disrupted RNA splicing with an excess of 5′ cryptic splicing events. Mutant U1-snRNA mediated alternative splicing inactivates tumor suppressor genes (PTCH1), and activates oncogenes (GLI2, CCND2), represents a novel target for therapy, and constitutes a highly recurrent and tissue-specific mutation of a non-protein coding gene in cancer.

Feasibility of Salvage Re-irradiation With Stereotactic Radiotherapy for Recurrent Glioma Using CyberKnife

AIM

To evaluate the toxicity and efficacy of re-irradiation with salvage stereotactic radiotherapy (SRT) for recurrent glioma using CyberKnife.

PATIENTS AND METHODS

This study retrospectively investigated 35 patients with 48 recurrent grade 2-4 gliomas who received SRT between 1998 and 2011. Six patients (17.1%) had grade 2 gliomas, nine (25.7%) had grade 3 gliomas, and 20 (57.1%) had glioblastomas; all initially underwent surgery and conventional radiotherapy. The median initial and subsequent radiotherapy doses were 60 and 26 Gy, respectively.

RESULTS

After a median follow-up period of 9.0 months, the only toxicity of grade 2 or more was radiation-induced brain necrosis in four patients (11.4%). The median overall and progression-free survival periods following re-irradiation were 9.0 and 3.0 months, respectively. Univariate analysis revealed that performance status at salvage re-irradiation was a significant predictor of progression-free survival.

CONCLUSION

Salvage re-irradiation using CyberKnife is feasible, with an acceptable toxicity profile, for patients with recurrent glioma.

A Hematogenous Route for Medulloblastoma Leptomeningeal Metastases

While the preponderance of morbidity and mortality in medulloblastoma patients are due to metastatic disease, most research focuses on the primary tumor due to a dearth of metastatic tissue samples and model systems. Medulloblastoma metastases are found almost exclusively on the leptomeningeal surface of the brain and spinal cord; dissemination is therefore thought to occur through shedding of primary tumor cells into the cerebrospinal fluid followed by distal re-implantation on the leptomeninges. We present evidence for medulloblastoma circulating tumor cells (CTCs) in therapy-naive patients and demonstrate in vivo, through flank xenografting and parabiosis, that medulloblastoma CTCs can spread through the blood to the leptomeningeal space to form leptomeningeal metastases. Medulloblastoma leptomeningeal metastases express high levels of the chemokine CCL2, and expression of CCL2 in medulloblastoma in vivo is sufficient to drive leptomeningeal dissemination. Hematogenous dissemination of medulloblastoma offers a new opportunity to diagnose and treat lethal disseminated medulloblastoma.