bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract

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

Abstract

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

Abstract

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

Abstract

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 &lt;0.1 for 49% (39/79), &gt;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

Abstract

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 &gt; 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

Abstract

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

Abstract

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

Abstract

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

Abstract

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.