bluuebunny/crossref_metadata_2025 huggingface dataset:
OS06.6A Inhibition of GBM invasion by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonist Perampanel
Authors: Sarnow K , Kanli G , Keunen O , Bjerkvig R
Published: September 2021

BACKGROUND

Extensive tumor cell invasion within the brain represents a major problem for effective treatment of glioblastomas (GBMs). The invasive processes can be divided into three types: Collective cell invasion, perivascular infiltration and single-cell invasion into the brain parenchyma. It has recently been shown that GBM cells have the ability to form synapses with neural cells pointing at an extensive communication network between brain cells GBM cells. This communication network can be mediated via the metabolites glutamine and glutamate both needed for GBM cell proliferation. In this context, it has been shown in preclinical models that Perampanel, an antiepileptic agent, functioning as non-competitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonist, has an inhibitory effect on GBM growth. In order to delineate how Perampanel affects GBM invasion, we here utilised a highly characterized 3D GBM-brain organoid invasion model where single-cell invasion was studied in real-time following Perampanel treatment.

MATERIAL AND METHODS

A brain coculture model, consisting of rat brain organoids expressing various markers of the human adult brain, where confronted with GFP-labelled tumor cells. By using time-lapse confocal microscopy, we quantified single-cell invasion patterns and speed of invasion using two glioma stem cell models (GSCs; BG5 and BG7).

RESULTS

Perampanel treatment significantly reduces tumor cell invasion into the brain organoids with the strongest effect seen in the most invasive GBM (BG5). Here, the single-tumor cell invasion ratio was reduced by 72 % compared to the control group (p=0.0033). In contrast, collective cell invasion was reduced by 19 % (p=0.028). Statistical analysis was performed using an unpaired sample t-test.

CONCLUSION

The AMPA glutamate receptor antagonist Perampanel significantly inhibits GBM invasion, suggesting an important role of the glutamate-glutamine cycle between the GBM cells and neurons in the invasion process. Moreover, this communication and exchange of metabolites seems to be more prominent where single GBM cells invade into the brain parenchyma compared to areas where collective invasion take place.
OS10.6.A Supportive care needs of TYA childhood brain tumour survivors and their caregivers: a mixed methods study
Authors: Nicklin E , Velikova G , Glaser A , Sarwar N , Kwok-Williams M , Debono M , Boele F
Published: September 2021

BACKGROUND

Childhood brain tumour survivors and their family caregivers can experience many late effects of treatment including social, cognitive and physical issues. Yet, the supportive care needs of survivors, now teenagers and young adults (TYAs), and their caregivers population are largely unknown. We aimed to gain an in-depth understanding of this populations’ supportive care needs.

MATERIAL AND METHODS

This study used a convergent mixed methods design including quantitative (survey) and qualitative data (in-depth semi-structured interviews). Participants were recruited from long-term follow-up clinics (in three NHS Trusts in England) and online. Participants included childhood brain tumour survivors, at least five years from diagnosis, currently aged 13–30 and their primary caregivers. The results from quantitative and qualitative data were integrated using a Joint Display Table.

RESULTS

136 eligible survivors and caregivers (78 survivors/58 caregivers) were approached to take part in the survey. In total, 112 participants (69 survivors/43 caregivers) completed the survey. A further 22 participants took part in face-to-face semi-structured interviews (11 survivors/11 caregivers). The integrated findings indicate that both survivors and caregivers have unmet needs many years after diagnosis. TYA survivors specifically had high unmet needs in relation to their psychological health, social lives (including romantic relationships), employment, and independence. Caregivers experienced even more unmet needs - including regarding their own psychological well-being and survivors’ financial issues. Survivors further from diagnosis, unemployed survivors and single caregivers were more likely to report unmet needs. Barriers preventing survivors and caregivers accessing supportive services were highlighted, including (but not exclusive to) families not being aware of support available, location of services, and accessibility to information/support.

CONCLUSION

This research provides leads to improving supportive care and long-term follow-up services. Understanding unmet needs and recognising what services are required is critical to improving survivor and caregiver quality of long-term survival.
OS11.5.A PATZ1 fusions define a novel molecularly distinct CNS tumor entity with a broad histological spectrum
Authors: Al Halabi K T , Sievers P , Stichel D , Sommerkamp A C , Sill M , Jäger N , Wittmann A , Kramm C , Snuderl M , Pfister S M , von Deimling A , Sahm F , Jones D T W
Published: September 2021

BACKGROUND

DNA methylation profiling has emerged as a useful tool for robust classification of rare CNS tumors with a broad morphological spectrum. Routine diagnostic molecular profiling performed in Heidelberg and at international collaborating centers revealed a small but recurring number of CNS tumors with fusions of the PATZ1 gene coupled to either MN1 or EWSR1, displaying a distinct genome-wide methylation profile; indicating that these tumors could form a seperate biological entity.

MATERIAL AND METHODS

We obtained genome-wide DNA-methylation array profiling of 68 primary CNS tumors. RNA-sequencing was perfomed on (n=23/68, 34%) of the tumor samples, including (n=6) from fresh frozen tissue used for gene expression profiling. For n=3 cases, whole exome sequencing (WES) data was generated, and gene panel sequencing data was available for n=13 cases, We systematically reevaluated the histopahthological features of 14 tumors, while immunohistochemical (IHC) staining with Ki-67, GFAP, MAP2, NeuN, Olig-2, Synaptophysin, S-100 and Vimentin was performed for (n=12) tumors. We finally collected clinical data to preliminarily characterize this novel tumor entity.

RESULTS

A selected analysis of the tumors in this novel cohort (n=68), compared with a reference cohort consisting of 15 other low- and high-grade glial and glioneuronal tumor classes, confirmed a clearly distinct grouping. No similarity was seen with the MN1:BEND2 and MN1:CXXC5-fused CNS-tumors. Analysis of Copy number profiles derived from the DNA-methylation data showed a mostly quite genome, with (n=64/65, 98%) of tumors showing copy number variations on Chromosome 22. RNA-sequencing detected PATZ1 fusions in all tumors sequenced (n=12; MN1:PATZ1, n=11; EWSR1:PATZ1). IGF2, PAX2 and GATA2, all genes involved in brain stem cell biology, were upregulated compared to a combined reference cohort of other glioma subtypes. DNA-sequencing showed no relevant alterations at the level of point mutations or small insertions/deletions. The tumors in our cohort showed polyphenotypic histologies along the glial spectrum, with a subset of tumors being diagnosed as Gliobastoma, WHO Grade 4 and bi- and multiphasic differentaion patterns being evident. IHC performed on tissue available did not favor a particular lineage, with most tumors showing immunopositivity to GFAP. Reverse translation of the gene expression data showed a potential role for NG2 as immunostaining marker. The median age was 11.0 years (0–80), (MN1:PATZ1 manifested at a younger age (median = 4 years) vs EWSR1:PATZ1 (median = 14 years)). Median PFS was 12 months.

CONCLUSION

We describe here a novel, molecularly distinct CNS tumor class with strikingly variable histopathologic morphology. We postulate that the PATZ1 fusions are a key driver of tumor initiation. Preliminary indications suggest an intermediate prognosis.
OS12.7.A Characterization of intra-tumoral heterogeneity and differential immune activation during malignant progression of meningiomas on single cell level
Authors: Blume C , Dogan H , Schweizer L , Wick W , Weller M , Mann M , Kalamarides M , von Deimling A , Schlesner M , Sahm F
Published: September 2021

BACKGROUND

As the most common intracranial tumor, meningiomas have caused increasing interest in the field of medical research. Based on their mutational profile, meningiomas can be separated into two main groups: NF2 altered meningiomas, which can occur at WHO grades 1 to 3, and non-NF2 mutant meningiomas with mutations in other genes, such as TRAF7, AKT1, KLF4, and SMO, which are usually of WHO grade 1. While this means that non-NF2 mutant meningiomas usually follow a benign course, risk stratification for NF2 mutant meningiomas remains difficult. As of now, the underlying mechanisms contributing to the malignant phenotype of some NF2 mutant meningiomas remained unknown, even though some molecular markers have been associated with an increased risk of recurrence. Here, we sought to characterize robust molecular subgroups for meningiomas and identify the critical steps in malignant progression of these tumors.

MATERIAL AND METHODS

We applied bulk RNA sequencing and proteomic analyses for 44 meningioma samples as well as single nuclei RNA sequencing analyses for an additional set of 26 meningiomas with a total of 46,002 nuclei. Both datasets comprised samples across the molecular landscape of meningiomas and WHO grades 1, 2, and 3.

RESULTS

The meningioma subgroups previously identified on epigenomic level were found consistently also on transcriptomic, proteomic, and phospho-proteomic levels. In addition, strong differences in numbers and types of infiltrating immune cells between subgroups became apparent. A decreased number of infiltrating macrophages and an activation to a more proinflammatory phenotype was observed for WHO grade 3 tumors. This observation correlated with lower expression levels of CSF1 in tumor cells of WHO grade 3 meningiomas, which was predicted to stimulate macrophages in WHO grade 1 and 2 tumors. Moreover, we identified several tumor cell subpopulations, each defined by a distinct phenotype, shared across samples. Their proportions in the tumor strongly depended on tumor grade. Especially a subpopulation characterized by an elevated stress response and TGFβ signaling activity was found specifically in WHO grade 3 cases.

CONCLUSION

Our findings establish molecular subgroups for meningiomas that are robust across multiple levels with characteristic differences in pathway activities and demonstrate a subtype-specific immune activation, both of which may be basis for novel treatment strategies.
P02.02 Modeling of response to irradiation in recurrence glioblastoma’s cells culture
Authors: Antipina N , Belyashova A , Pavlova G , Nikolaeva A , Savchenko E , Ovechkina A , Shamadykova D , Golanov A
Published: September 2021

BACKGROUND

Radiosensitivity of glioblastoma (GB) cells of local relapses may be markedly different from the primary tumor. Optimal doses and regimes of re-irradiation GB recurrence is not determined yet.

MATERIAL AND METHODS

GO1 primary GB cell culture was obtained during removal of a recurrent tumor after combined treatment, including irradiation of the surgical bed. Сell’s culture was irradiated by photon beams with energy 6 MeV and dose rate 600 MU/min. Irradiation performed in 1, 3 and 5 fractions, by 10 different doses for each regime. The dose range was determined experimentally for one fraction (5–250 Gy); for other regimes it was calculated according to the biological equivalent dose conception (3 fractions: 5–450 Gy, 5 fractions: 5–550 Gy). The proliferative activity of cells was investigate by MTT test. The results were normalized to the control. Dose-effect curves were plotted for each irradiation regime.The experimental data were approximated by calculated curves obtained by selecting the optimal parameters of the LQ-model and it’s modification.

RESULTS

Irradiation of GO1 by 1 fraction with the dose 5–250 Gy, causes a slow decrease in proliferative activity, which reaches a minimum value of 23% at 150 Gy and then remains constant. After irradiation by 3 fractions, proliferative activity of the GO1 gradually decrease only at a total dose over 120 Gy and reaches 37% after 450 Gy. When GO1 was irradiated in 5 fractions, a similar dose-effect curve was obtained, gradual decrease was observed to a value of 52% in the range of 250–500 Gy. Thus, the experimental dose-effect curves for irradiation of recurrence GB cells for 3 and 5 fractions have the appreciable “shoulder”, which could be explained by increased radioresistance. When approximating the experimental data by fitting the parameters of the LQ-model, the use of α/β = 8 provided the slope of the curve, close to the experimental data. For reflecting the “shoulder” an additional summand was introduced into the mathematical expression for the number of proliferating cells - a 105 Gy for 3 fractions and 255 Gy for 5 fractions.

CONCLUSION

Modified LQ-model could be used for an adequate mathematical description of the effectiveness of fractionated irradiation in relapsed GB culture cells in vitro. It’s necessary to introduce a summand into the formula that determines the formation of a “shoulder” on the dose-effect curve for this. The research was supported financially by RFBR (Project No. 18-29-01061).
P04.04 Optimizing dasatinib for glioblastoma treatment
Authors: Alhalabi O , Göttmann M , Gold M , Fletcher M , Hielscher T , Iskar M , Kessler T , Wittmann E , Schlue S , Rahman S , Hai L , Hansen-Palmus L , Puccio L , Nakano I , Herold-Mende C , Baumgartner U , Day B , Wick W , Sahm F , Fraenkel E , Phillips E , Goidts V
Published: September 2021

BACKGROUND

Glioblastoma is the most common primary malignancy of the central nervous system with a dismal prognosis, even with surgical and chemoradiotherapy. Expression profiling studies classify IDH-wildtype Glioblastoma into three subtypes: Proneural (PN), mesenchymal (MES) and classical (CL). A promising target to inhibit in Glioblastoma is the non-receptor tyrosine kinase and proto-oncogene SRC. After robust pre-clinical results, SRC inhibitors like dasatinib did not improve survival of Glioblastoma patients after recurrence in clinical trials.

MATERIAL AND METHODS

Consolidating efforts to personalize cancer therapy, we use in silico analyses backed by in vitro and in vivo experiments on Glioblastoma stem-like cells (GSCs) derived from primary patient tumors to present a novel stratification strategy for dasatinib therapy in glioblastoma. To further tackle dasatinib resistance in GSCs, a pooled shRNA library against 5000 genes was combined with dasatinib to identify genes whose knockdown sensitizes GSCs to dasatinib. This was integrated with proteomics and phosphoproteomics data of dasatinib inhibited GSCs.

RESULTS

We found MES tumors with high expression of SERPINH1 to be sensitive to dasatinib inhibition, compared to the CL and PN subtypes. Interestingly, SRC phosphorylation status did not predict the efficacy of dasatinib inhibition. Computational analyses integrating data from the loss-of-function dropout viability screen and proteomics/phosphoproteomics using a novel modification of the SamNet algorithm identified Wee1, a tyrosine kinase involved in cell-cycle signaling, as a potential combination inhibition target with dasatinib. Further validation experiments showed a robust synergistic effect through combination of dasatinib and the wee1 inhibitor, MK-1775 in PN GSCs.

CONCLUSION

This study highlights strategies to optimize dasatinib treatment in different glioblastoma subtypes. While the stratification of patients harboring mesenchymal glioblastoma with SERPINH1 overexpression could provide an option in this particular subtype, combining dasatinib or other SRC inhibitors with Wee1 inhibitors could present an additional possibility for treating resistant proneural tumors
P04.06 Can BraTS Toolkit Brain Tumor Segmentation Algorithms be relevant when dealing with post-operative MRI in clinical practice?
Authors: Piram L , Acquitter C , Sabatini U , Lemasson B , Moyal E , El Idrissi S , Ken S
Published: September 2021

BACKGROUND

Segmentation of brain tumors is crucial for radiotherapy plans and treatment outcome evaluation. As manual segmentation (MS) is a time-consuming task, many algorithms to automate the process were proposed over the past decades. BraTS toolkit (BTK) offers a solution for automatic brain tumor segmentation in 3 steps: a Preprocessor for image conversion and registration, a Segmentor generating segmentations from 4 deep-learning based algorithms and a Fusionator combining the results. As most algorithms published, BTK was trained on pre-operative data. Yet, as surgery is the first treatment of glioblastomas, most MRIs in clinical practice are post-operative images. This study aimed to assess whether segmentation of post-operative brain tumors could benefit from an initial automatic segmentation (AS) using BTK.

MATERIAL AND METHODS

MRI dataset from the multicenter, STERIMGLI clinical trial provided 92 series from 25 patients with a unifocal recurrence of glioblastoma. AS were generated using BTK Preprocessor and Segmentor. Out of the 4 algorithms output, the best AS was selected after visual appraisal. AS contained 3 labels: T1w contrast enhanced tumor (ET), flair edema (ED) and non-enhanced tumor (NET). AS were then reviewed by a radiation oncologist and a neuroradiologist to produce the MS. ET and ED were corrected; surgical cavity (SC) was also segmented, either from the NET label or de novo. Dice-score, Hausdorff Distance (HD) and Average Hausdorff Distance (AHD) were used to quantify the similarity between AS and MS for each label.

RESULTS

AS succeeded to label 89.3% (82/92), 100% (92/92) and 85.8% (79/92) of ET, ED and NET respectively. Among the 4 algorithms in BTK, Zyx_2019 produced 36% of AS, mic-dkfz 32%, xfeng 18%, lfb_rwth 14%. Mean Dice-scores of 75.8%, 94.8% were found for ET and ED respectively. Mean HD and AHD were 25.2mm (±39.7), 2.8mm (±10.9) for ET; 14.9mm (±25.8), 0.9mm (±5.8) for ED. Concerning SC, Dice-scores were <0.1 for 49% (39/79), >0.6 for 30% (42/79).

CONCLUSION

BraTS Toolkit was trained to segment necrosis as the label NET. Still, it detected the surgical cavity and saved time for the MS in 51% of post-operative cases. Even though BTK was designed to segment pre-operative brain tumors, similarity metrics show that minimal or no manual corrections are necessary most of the time when used to segment ET and ED on post-operative MRI acquired in clinical routine. The development of a unique AS tool for pre and post-operative images would be useful in clinical practice.
P04.08 Biopsy-only glioblastoma (BO-GBM) as a heterogeneous group of patients
Authors: Harlay V , Loundou A , Boucard C , Petrirena G , Barrie M , Campello C , Autran D , Padovani L , Figarella D , Boissonneau S , Dufour H , Baumstarck K , Tabouret E , Chinot O
Published: September 2021

BACKGROUND

“Biopsy-only” glioblastoma is associated with a heterogeneous functional and survival outcome. BO-GBM patients is an understudied group of patients associated to a poor outcome, which has been reported to represent 21% of histologically confirmed GBM in the US National Cancer Data Base. Pattern of care included radiotherapy-temozolomide (RT-TMZ) standard regimen completed in 15% of patients, any other form of oncologic treatment in 60%, and supportive care alone in 25% of patients. Our objective was to explore pattern of care and prognosis associated to BO-GBM in our center.

MATERIAL AND METHODS

Patients with BO-GBM included in a prospective regional glioma SIRIC cohort initiated in 2014 and closed in 2017 were retrospectively reviewed for patients characteristics, MRI finding, treatment allocation and delivery. PFS and OS were analyzed.

RESULTS

Of 535 patients included in the cohort, 86 patients were referred > 3 months post-surgery and were excluded from this analysis while 449 patients were included at initial surgery, of which 158 patients (35%) underwent biopsy only. Of 158 patients, 18 patients were excluded for missing data leaving 139 patients for the present analysis. Fifty-four (39%) were referred to RT-TMZ (50 patients completed concomitant treatment), 68 (49%) considered unfitted for RT received chemotherapy upfront (CT-UF) (of which 4 were subsequently referred to RT), 17 (12%) were referred to palliative care only (PC). Groups differed at baseline for age (mean 60, 68, and 69 years, for RT-TMZ, CT-UF, and PC respectively); for KPS (70, 60, and 50 for RT-TMZ, CT-UF, and PC respectively); for mean tumor surface measured on gadolinium-enhanced T1-weighted (793, 1420, 1412 mm2 for RT-TMZ, CT-UF, PC); for tumor extension (bilateral in 6.4% and 29.3% for RT-TMZ and CT-UF respectively); for mean steroid intake (45, 60, 100 mg daily respectively). Median OS was 14 months (95% CI, 9.65–18.71), 8 months (95% CI, 4.62–7.67), and 2 months (95% CI, 0.67–3.33) for RT-TMZ, CT-UF, and PC respectively.

CONCLUSION

Inoperable GBM constitute a large and heterogeneous population in which one third of patients are amenable to standard of care, with survival outcome close to the one of patients who underwent surgery. Patients considered unfit for RT-TMZ at diagnosis fail to be referred subsequently to RT after CT and exhibit a poor survival outcome. Thus, reliable criteria are needed to help selecting patients for adequate treatment while new strategies are warranted for BO-GBM unfit for RT.
P04.14 Sporadic wild-type multiple meningiomas harbor distinct driver mutations
Authors: Juratli T , Prilop I , Saalfeld F , Meinhardt M , Schackert G , Pinzer T
Published: September 2021

BACKGROUND

Multiple meningiomas (MM) are rare and present a unique management challenge. While the mutational landscape of single meningiomas has been extensively studied, understanding of the molecular pathogenesis of sporadic MM remains incomplete. The objective of this study is to elucidate the genetic features of sporadic MM.

MATERIAL AND METHODS

We identified eight patients with MM (n=17) defined as ≥2 spatially separated synchronous or metachronous meningiomas. We profiled genetic changes in these tumors using a next generation sequencing (NGS) assay that covers a large number of targetable and frequently mutated genes in meningiomas including AKT1, KLF4, NF2, PIK3CA/PIK3R1, POLR2A, SMARCB1, SMO, SUFU, TRAF7, and the TERT promoter.

RESULTS

Most of MM were WHO grade 1 (n= 14, 82.3%). Within individual patients, no driver mutation was shared between separate tumors. All but two cases harbored different hot spot mutations in known meningioma-driver genes like TRAF7 (n= 5), PIK3CA (n= 3), AKT1 (n= 3) and SMO (n= 1). Moreover, individual tumors differed in histologic subtype in 7/8 patients. The low frequency of NF2 mutations in our series stands in contrast to previous studies that included hereditary cases arising in the setting of neurofibromatosis type 2 (NF2).

CONCLUSION

Our findings provide evidence for genomic inter-tumor heterogeneity and an independent molecular origin of sporadic NF2 wild-type MM. Furthermore, these findings suggest that genetic characterization of each lesion is warranted in sporadic MM.
P04.15 Radiomics features in prediction of pseudo-progression and response to hypofractionated stereotactic radiotherapy and anti-PDL1 Durvalumab combination in recurrent glioblastoma from STERIMGLI phase I trial
Authors: Glemarec G , Pouessel D , Mervoyer A , Larrieu-Ciron D , Carrabou B , Robert M , Frenel J , Mounier M , Cohen-Jonathan Moyal E , Ken S
Published: September 2021

BACKGROUND

Due to the risk of pseudo-progression, evaluating the response of such combined treatment with anti-PDL1 immunotherapy and hypofractionated stereotactic radiotherapy (hFSRT) in patients with recurrent glioblastoma (GBM) is difficult even with iRANO criteria. We aim to analyze multi-modal MRI radiomic features in recurrent GBM patients included in the phase I STERIMGLI (NCT02866747) clinical trial.

MATERIAL AND METHODS

In phase I trial STERIMGLI, six patients received hFSRT 24 Gy in 3 fractions of 8 Gy prescribed to the 80% covering isodose in combination with Durvalumab IV 1500mg the same day following the third fraction of radiation then every 4 weeks for a maximum of 12 months. All patients underwent multi-modal MRI acquisitions. Contrast-enhancement on post-gadolinium T1 MRI (Gd-T1) and hyper-T2 signal on FLAIR MRI were manually segmented as volume-of-interest (VOIs) from baseline at week 0 (W0) and every eight weeks until weeks sixteen (W16). For patient 05, segmentation was performed until progression (W40). First order radiomics were extracted and normalized from these longitudinal VOIs in a total of 42 MRI: volume (in cm3), mean and median intensity, entropy, skewness and kurtosis were computed for each VOI. In total 504 (2 x 42 x 6) features were extracted.

RESULTS

Two patients underwent pseudoprogression (patients 04 and 05).

All patients but one (patient 05) presented an early relapse with an increase of FLAIR and Gd-T1 volumes and respective entropies from the first evaluation without decrease during follow up (until W16).

Patient 05 presented a Dose Limiting Toxicities and had the longest time to progression after Durvalumab and hFSRT. Contrary to the other patients, his FLAIR radiomics features presented a decrease of volume, intensity and entropy between W0 and W16 then, interestingly an increase between W24 and W40, date of progression. Moreover, patient 05 presented the lowest tumor volume and the lowest Gd-T1entropy. The intensity of the Gd-T1 followed the same trend as the hyper intense signal on the FLAIR in all patients, in particular for patient 05.

CONCLUSION

In our study, entropy and tumor volume for both FLAIR and Gd-T1, and FLAIR intensity seems to be the most interesting parameters to access the response of combined treatment. FLAIR signal may be more specific to the tumor microenvironment.

First order radiomics allowed us to follow tumor heterogeneity and identify the patient with the longest time to progression.
P04.18 Heterogeneity and plasticity of integrin α5β1 expression in glioblastoma stem cells
Authors: Messé M , Bernhard C , Mercier M , Fuchs Q , Foppolo S , Herold-Mende C , Namer I , Bund C , Elati M , Entz-Werlé N , Dontenwill M
Published: September 2021

BACKGROUND

Glioblastoma (GBM) is the most frequent and deadliest type of central nervous system tumors. Despite the treatment by the Stupp protocol, almost all patients relapse and new therapeutic protocols have been unsuccessful for ameliorating patient survival. Molecular heterogeneity of GBM and existence of glioma stem cells (GSC) may be linked to therapy resistance and recurrence. We demonstrated earlier that α5β1 integrin is a GBM therapeutic target which participate to therapy resistance; a high expression in patient tumors is linked to a worse prognosis. Expression of α5β1 integrin is heterogeneous inter- and intra-tumorally. We particularly addressed the role of glioma stem cell plasticity in the modulation of the integrin expression. Stem cells reside in specific niches (perivascular or hypoxic niches) in the tumor and are at the origin of the more differentiated tumor cell bulk. Metabolism is known to change between the different GSC states and may be affected by or may affect the integrin expression. The aim of our work is therefore to consider the expression of the integrin α5β1 in relationship with GSC differentiation or in hypoxic environment and with cell metabolism.

MATERIAL AND METHODS

Ten different patient-derived glioma stem cell lines were investigated. Cell culture in stem cell medium (neurospheres) or differentiation medium (adherent cell monolayer) was made in normoxia (21% O2) or hypoxia (1%O2). Alternatively, chemically-induced hypoxia (cobalt chloride/desferoxiamine) was used. Integrin expression was kinetically checked at the mRNA (RT-qPCR) or protein (Western blot) levels. Cell metabolism was investigated with the Seahorse Xfp technology and by HRMAS-NMR.

RESULTS

No GSC lines (neurospheres) expressed the α5β1 integrin. Interestingly, only half of them did after differentiation suggesting a first level of heterogeneity. A second level of heterogeneity was observed in hypoxic conditions provoking induction of integrin α5β1 expression in only some non-differentiated GSC. Three categories of GSC were thus characterized: one able to express the integrin in hypoxia and after differentiation, one never expressing it and the third one only after differentiation. Cell metabolism differed between GSC before and after differentiation and in presence of integrin α5β1 antagonists. Specific glioma regulator network analysis revealed new targets to be inhibited concomitantly with the integrin.

CONCLUSION

Data suggest that α5β1 integrin expression may be induced by different signaling pathways. Molecular switches may occur either when stem cells differentiate to tumor cells but also directly in stem cells in hypoxic niches. Characterization of α5β1 integrin expression drivers may help to find new therapeutic targets but also to delineate subpopulation of patients who would benefit from an anti-integrin strategy.
P05.01 Prospective validation trial of magnetic resonance imaging based Contrast Clearance Analysis (CCA) to differentiate between pseudoprogression/radiation necrosis and progressive disease following cranial radiotherapy
Authors: Bodensohn R , Forbrig R , Lietke S , Reis J , Boulesteix A , Albert N L , Dorostkar M , Corradini S , Belka C , Thon N , Niyazi M
Published: September 2021

BACKGROUND

Pseudoprogression (PsP) or radiation necrosis (RN) may frequently occur after cranial radiotherapy and show a similar imaging pattern compared to progressive disease (PD). Even for experienced neuroradiologists, it remains challenging to distinguish between these clinically relevant disease states. We aimed to evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) based Contrast Clearance Analysis (CCA) in this clinical setting.

MATERIAL AND METHODS

Patients with equivocal imaging findings after cranial radiotherapy were consecutively included into this monocentric prospective study. Assuming a true accuracy of 90% and setting the significance level to 0.05, N=33 patients are required to show that accuracy is larger than 70% with a power of 80% using a one-sided binomial test. CCA was performed by subtraction of imaging features in late vs early T1-weighted sequences after contrast-agent application. Two experienced neuroradiologists evaluated CCA with respect to PsP/RN and PD being blinded for FET PET and histological findings; histopathological diagnosis was based on stereotactic biopsy or resection for space-occupying processes. The radiological assessment was compared with the histopathological results, and its accuracy was calculated statistically.

RESULTS

Thirty-three patients were included; sixteen (48.5%) were treated because of a primary brain tumors, and 17 (51.1%) with brain metastases. In one patient, CCA was technically infeasible. The accuracy of CCA in predicting the histological result was 0.84 (95% CI 0.67–0.95; one-sided p=0.05; N=32). An accuracy of 0.85 (95% CI 0.68–0.95; one-sided p=0.04) would have been obtained in case of a correct classification in the non-analyzable case. Sensitivity and specificity of CCA were 0.93 (95%-CI 0.66–1.00) and 0.78 (95% CI 0.52–0.94), respectively. The accuracy in metastases patients was 0.94 (95% CI 0.71 - 1.00) and non-significantly higher compared to primary brain tumor patients with accuracy of 0.73 (95% CI 0.45 - 0.92), p=0.16.

CONCLUSION

In this study, CCA was a highly accurate, easy and helpful method for distinguishing PsP or RN from PD after cranial radiotherapy, especially in brain metastases patients after radiosurgical treatment.
P06.05 The Sitting Position in the Very Young Pediatric Population: Pearls and Pitfalls of a 10-Years’ Experience
Authors: Linsler S , Teping F , Oertel J
Published: September 2021

BACKGROUND

To investigate pearls and pitfalls of the sitting positioning in the pediatric population with special focus on related morbidity and surgical practicability.

MATERIAL AND METHODS

A retrospective analysis of a prospectively maintained internal database was performed. All pediatric patients younger than 18 years at date of surgery, who underwent procedures in sitting position between 01/2010 and 10/2020 were included into this analysis.

RESULTS

A total of 42 of posterior fossa surgeries were performed in 38 children between 01/2010 and 10/2020. Mean age at surgery was 8.9 years (13 months - 18 years). Mean height and weight were 134.4 (± 30.2) cm and 36.6 (± 21.7) kg respectively. Three children (7.9%) were diagnosed with persistent foramen ovale. Electrophysiologic monitoring was unremarkable during positioning in all cases. Mean time needed for anesthesiologic preparation and positioning was 84.5 (± 20.6) minutes. Perioperative blood transfusion was needed in 5 cases (11.9%). Incidence of VAE was 11.9%. There was no VAE related severe complication. One child (2.4%) showed postoperative skull fracture and epidural bleeding due to skull clamp application. Clinical status immediately after surgery was favorable or stable in 33 of the cases (78.6%).

CONCLUSION

Attentive performance and an experienced surgical team provided; the sitting position remains a safe variant for posterior fossa surgery in the pediatric population. Precautious skull clamp application and appropriate monitoring is highly recommended. Considering eloquent aspects, the sitting position offers excellent anatomical exposure and is ideal for combination with endoscopic techniques.
P07.04 Rapid-CNS2: Rapid comprehensive adaptive nanopore-sequencing of CNS tumors, a proof of concept study
Authors: Dogan H , Patel A , Herold-Mende C , Pfister S , Wick W , Loose M , von Deimling A , Sill M , Jones D , Sahm F
Published: September 2021

BACKGROUND

The WHO classification 2021 includes multiple molecular markers for routine diagnostics in addition to histology. Sequencing setup for complete molecular profiling requires considerable investment, while batching samples for sequencing and methylation profiling can delay turnaround time. We introduce RAPID-CNS2, a nanopore adaptive sequencing pipeline that enables comprehensive mutational, methylation and copy number profiling of CNS tumours with a single third generation sequencing assay. It can be run for single samples and offers highly flexible target selection requiring no additional library preparation.

MATERIAL AND METHODS

Utilising ReadFish, a toolkit enabling targeted nanopore sequencing, we sequenced DNA from 22 diffuse glioma patient samples on a MinION device. Target regions comprised our Heidelberg brain tumour NGS panel and pre-selected CpG sites for methylation classification by an adapted random forest classifier. Pathognomonic alterations, copy number profiles, and methylation classes were called using a custom bioinformatics pipeline. Results were compared to their corresponding NGS panel-seq and EPIC array outputs.

RESULTS

Complete concordance with the EPIC array was found for copy number profiles from RAPID-CNS2. 94% pathognomonic mutations were congruent with NGS panel-seq. MGMT promoter status was correctly identified in all samples. Methylation families were detected with 96% congruence. Among the alterations decisive for rendering a classification-compatible integrated diagnosis, 97% of the alterations were consistent over the entire cohort (completely congruent in 19/22 cases and sufficient for unequivocal diagnosis in all).

CONCLUSION

RAPID-CNS2 provides a swift and highly flexible alternative to conventional NGS and array-based methods for SNV/Indel analysis, detection of copy number alterations and methylation classification. The turnaround time of ~4 days can be further shortened to <12h by altering target sizes. It offers a low-capital approach that would be cost-efficient for low throughput settings and invaluable in cases requiring immediate diagnoses.
P09.01 Radiomics-based machine learning approach in differentiation between vestibular schwannoma and meningioma in the cerebellopontine angle
Authors: Zhang Y , Chen C , Xu J
Published: September 2021

BACKGROUND

Vestibular schwannoma (VS) and meningioma are the most two common tumors in the cerebellopontine angle (CPA). Accurate preoperative differentiation of the two lesions is important due to their different surgical approaches and outcomes for the preservation of hearing and facial nerve function. Magnetic resonance (MR) scan is commonly performed to preoperatively evaluate CPA tumors and to differentiate VS from meningioma in clinical routine. However, in some cases, overlaps of conventional MR imaging patterns between the two lesions could make preoperative diagnosis challenging. The purpose of this study is to investigate the ability of radiomics, a novel method providing objective and quantitative information beyond visual assessment, in differentiation between VS and meningioma located at CPA using machine learning technology.

MATERIAL AND METHODS

This retrospective study enrolled eligible patients who were diagnosed with VS (N = 50) or meningioma (N = 41) in the CPA. A set of mineable three-dimensional radiomic parameters were extracted from preoperative contrast-enhanced T1-weighted images. Optimal features were selected first with three selection methods including distance correlation, least absolute shrinkage and selection operator (LASSO) and gradient boosting decision tree (GBDT). Then three machine learning classification algorithms, namely linear discriminant analysis (LDA), support vector machine (SVM) and random forest were employed to build discriminative models. Area under the curve (AUC), accuracy, sensitivity and specificity were calculated to assess the performance of each model.

RESULTS

Nine models were established with different combinations of selection methods and machine learning classifiers. Three classifiers with the suitable selection method all represented feasible ability in differentiation with AUC more than 0.86 in the validation set, and LDA-based models seemed to show better diagnostic performance than those based on the other two classifiers. The combination of LASSO and LDA classifier was found to show the highest AUC of 0.942 in the validation set.

CONCLUSION

Radiomics-based models via machine learning approaches could potentially be utilized to assist in preoperative differentiation between VS and meningioma in the CPA.
P13.04 Survival analyses for determining clinical relevance of molecular markers in translational glioblastoma research - a systematic review
Authors: Fitt B , Loy G , Christopher E , Brennan P M , Poon M T C
Published: September 2021

BACKGROUND

Pre-clinical glioblastoma studies can assess the relevance of their findings to patient survival using integrated clinical and genomic data. Validity of univariable analyses requires an assumption that molecular markers are randomly distributed across patient characteristics to mitigate the confounding effects of clinical variables. Multivariable survival analyses adjusting for clinical variables do not change the association if this assumption holds. We aimed to assess this by summarising the types of survival analyses and their results in translational glioblastoma research.

MATERIAL AND METHODS

We systematically searched Medline and Embase Jan 2008 to Feb 2021 for glioblastoma cell line or animal studies validating their molecular markers in The Cancer Genome Atlas (TCGA) or the Chinese Glioma Genome Atlas (CGGA) using survival analyses. Studies that exclusively used genomic data without laboratory findings were excluded. Two reviewers independently assessed study eligibility and extracted data. Data items included patient inclusion criteria, characteristics of survival analyses, and whether molecular markers had statistically significant association with overall survival.

RESULTS

Of 1,047 potentially eligible studies, we included 59 pre-clinical glioblastoma studies that tested the association between their molecular markers and survival using TCGA or CGGA data. All studies used TCGA data and 2 also used CGGA data. Sixteen (27%) studies specified their patient inclusion criteria from TCGA for survival analysis. Eight studies exclusively investigated sets of molecular markers, leaving 51 studies reporting 126 molecular markers. Eighteen (31%) studies used multivariable survival analysis in addition to univariable analyses. All molecular markers underwent univariable analyses, of which 12 (10%) molecular markers had additional multivariable survival analyses. In the 13 multivariable analyses on 12 molecular markers, four (31%) markers were associated with survival in the univariable analyses but not in the multivariable analyses.

CONCLUSION

Most pre-clinical studies used univariable survival analyses alone in public genomic repositories to assess the relevance of their results to patient survival. Our findings demonstrated that multivariable analyses are needed to account for confounding effects of clinical variables. Using relevant components from reporting guidelines for observational studies can improve the transparency and quality of translational studies.
P13.07 Cysteine induces glioblastoma cytotoxicity through mitochondrial reductive stress
Authors: Noch E , Palma L , Yim I , Barnett D , BHinder B , Benedetti E , Krumsiek J , Elemento O , Cantley L
Published: September 2021

BACKGROUND

Glioblastoma (GBM) remains a poorly treatable disease with high mortality. Tumor metabolism in GBM is a critical mechanism responsible for accelerated growth because of upregulation of glucose, amino acid, and fatty acid utilization. However, therapies targeting GBM metabolism, whether through the use of small-molecule compounds or dietary interventions to limit nutrient sources, have failed in clinical trials. Metabolic bypass is an important mechanism that is often overlooked in GBM trials, since many trials have focused instead on combining anti-metabolic therapy with cytotoxic treatments. The goal of this research is to use a multi-pronged treatment approach with targeted drug and dietary therapy to leverage metabolic susceptibilities in GBM.

MATERIALS AND METHODS

We first interrogated the TCGA database and a cancer metabolite database for alterations in glucose and amino acid signatures in GBM relative to other human cancers and relative to low-grade glioma. We identified the amino acid cysteine as contributing to a novel metabolic susceptibility pathway in GBM. To study the role of cysteine in GBM pathogenesis, we treated patient-derived GBM cells with a variety of FDA-approved cysteine-promoting compounds in vitro, including N-acetylcysteine (NAC). We measured cell proliferation, energy production, mitochondrial metabolism, and reactive oxygen species to study mechanisms of oxidoreductive stress. Results: From our TCGA and cancer metabolite database analyses, we found that GBM exhibits the highest levels of cysteine and methionine pathway gene expression of 32 human cancers and that GBM exhibits high levels of cysteine-related metabolites compared to low-grade gliomas. Cysteine compounds, including NAC, reduce growth of GBM cells, which is exacerbated by glucose deprivation. This growth inhibition is associated with reduced mitochondrial metabolism, manifest by reduction in ATP generation, NADPH/NADP+ ratio, mitochondrial membrane potential, and oxygen consumption rate. Through measurement of mitochondrial hydrogen peroxide, we found that NAC-treated cells exhibit a paradoxical increase in mitochondrial hydrogen peroxide levels, likely due to inhibition of thioreductase and glutathione reductase systems. Through genetic and pharmacological studies, we found that induction of thioredoxin-2 rescues NAC-mediated cytotoxicity and that inhibition of thioreductase and glutathione reductase exacerbates mitochondrial toxicity and reductive stress.

CONCLUSIONS

We show that cysteine compounds reduce cell growth and induce mitochondrial toxicity in GBM through reductive stress. This metabolic phenotype is exacerbated by glucose deprivation. This pathway is targetable with FDA-approved cysteine-promoting compounds and could synergize with glucose-lowering treatments, including the ketogenic diet, for GBM.
P13.22 Menglia: an innovative approach to liquid biopsies in glioma patients
Authors: Truffelli M , Petretto A , Candiano G , Giunti D , Vigo T , Gaggero G , Bennicelli E , Grassi M , Zona G , Fiaschi P
Published: September 2021

BACKGROUND

Gliomas are the second most frequent primary brain tumor. Since 2016 gliomas are classified according to histological, and molecular features such as IDH status and 1p19q codeletion. Recently oncological research has focused on liquid biopsies to reduce the need for invasive diagnostic tests. Cerebrospinal fluid (CSF) is the principal source of brain tumor biomarkers. Modern technologies currently allow us to analyze proteomic and metabolomic tumor profiles, in order to find new biomarkers without being constrained by a priori hypothesis. Several data from the literature also suggests that inflammatory cells and cytokines in tumors contribute to tumor growth, progression and immunosuppression. The possibility of simultaneously testing different inflammatory molecules on the biological fluids could lead to the identification of new biological markers with prognostic and predictive value for treatment response.

STUDY OBJECTIVES

- Identification of protein and/or lipid biomarkers specific to the glioma subgroup among those under analysis. - Identification of tumor group- and subgroup-specific CSF and/or serum inflammatory biomarkers among those tested. - Correlation of biomarkers with Progression Free Survival (PFS), Overall Survival (OS).

ELIGIBILITY CRITERIA

- Patients with a radiological suspected diagnosis of glioma eligible for surgery. - Age ≥ 18 years. - Availability of histological samples, CSF, blood and urine. - Patients with unconfirmed histological diagnosis of glioma will be excluded. - Patients who have never received any systemic or local treatment for CNS diseases.

STUDY DESIGN

This is a prospective monocentric study involving mass spectrometry analysis for characterization of proteins and metabolites and ELISA analysis for the characterization of different cytokines in parallel anonymized biological samples consisting of tumor tissue, CSF, blood and urine from glioma patients, divided into three different molecular subtypes: 1p19q codelet/IDH mutated, 1p19q non-codelet/IDH mutated and 1p19q non-codelet/IDH wt. Biological samples will be taken at surgery, at 24–48 h after surgery and every 3 months up to 1 year. The control group will include patients with subarachnoid hemorrhage or hydrocephalus, either undergoing external ventricular shunting or undergoing ventricular catheter placement/revision surgery.

STUDY ANALYSIS

Data interpretation will be based on a statistical analysis of the data, applying tools such as Principal Component Analysis (PCA) Weighted Correlation Network Analysis (WGNCA), Multiple Venn Diagram, T-Test, ANOVA, Clustering and Gene Ontology Enrichment, non-parametric Mann-Whitney test. For the assessment of clinical outcome, survival curves will be compared between different groups of patients who share a similar protein/metabolomic/inflammatory profile.