bluuebunny/crossref_metadata_2025 huggingface dataset:
A geostatistical analysis of multiscale metallicity variations in galaxies – I. Introduction and comparison of high-resolution metallicity maps to an analytical metal transport model
Authors: Metha Benjamin , Trenti Michele , Chu Tingjin
Published: September 2021

Thanks to recent advances in integral field spectroscopy, modern surveys of nearby galaxies are capable of resolving metallicity maps of H ii regions down to scales of ∼50 pc. However, statistical analyses of these metallicity maps has seldom gone beyond fitting basic linear regressions and comparing parameters to global galaxy properties. In this paper (the first of a series), we introduce techniques from spatial statistics that are well suited for detailed analysis of both small- and large-scale metallicity variations within the interstellar medium (ISM) of local galaxies. As a first application, we compare the observed structure of small-scale metallicity fluctuations within seven local galaxies observed by the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) collaboration to predictions from a stochastic, physically motivated, analytical model developed by Krumholz & Ting. We show that while the theoretical model underestimates the amount of correlated scatter in the galactic metallicity distributions by 3–4 orders of magnitude, it provides good estimates of the physical scale of metallicity correlations. We conclude that the ISM of local spiral galaxies is far from homogeneous, with regions of size ∼1 kpc showing significant departures from the mean metallicity at each galactocentric radius.
Structural dissection of sequence recognition and catalytic mechanism of human LINE-1 endonuclease
Authors: Miller Ian , Totrov Max , Korotchkina Lioubov , Kazyulkin Denis N , Gudkov Andrei V , Korolev Sergey
Published: September 2021

Long interspersed nuclear element-1 (L1) is an autonomous non-LTR retrotransposon comprising ∼20% of the human genome. L1 self-propagation causes genomic instability and is strongly associated with aging, cancer and other diseases. The endonuclease domain of L1’s ORFp2 protein (L1-EN) initiates de novo L1 integration by nicking the consensus sequence 5′-TTTTT/AA-3′. In contrast, related nucleases including structurally conserved apurinic/apyrimidinic endonuclease 1 (APE1) are non-sequence specific. To investigate mechanisms underlying sequence recognition and catalysis by L1-EN, we solved crystal structures of L1-EN complexed with DNA substrates. This showed that conformational properties of the preferred sequence drive L1-EN’s sequence-specificity and catalysis. Unlike APE1, L1-EN does not bend the DNA helix, but rather causes ‘compression’ near the cleavage site. This provides multiple advantages for L1-EN’s role in retrotransposition including facilitating use of the nicked poly-T DNA strand as a primer for reverse transcription. We also observed two alternative conformations of the scissile bond phosphate, which allowed us to model distinct conformations for a nucleophilic attack and a transition state that are likely applicable to the entire family of nucleases. This work adds to our mechanistic understanding of L1-EN and related nucleases and should facilitate development of L1-EN inhibitors as potential anticancer and antiaging therapeutics.
PL02.3. A Phenotypic heterogeneity and plasticity as resistance mechanisms in Glioblastoma
Authors: Yabo Y Y , Oudin A , Skupin A , Nazarov P V , Niclou S P , Golebiewska A
Published: September 2021

BACKGROUND

Glioblastomas are among the most heterogeneous tumors, which hampers patient stratification and development of effective therapies. Glioblastomas create a dynamic ecosystem, where heterogeneous tumor cells interact with the tumor microenvironment to establish different niches. Upon tumor growth, Glioblastoma cells manifest remarkable plasticity and respond flexibly to selective pressures by transiting towards states favorable to the new tumor microenvitonment. How this phenotypic plasticity contributes to treatment resistance is currently less clear. The exact nature of treatment resistant, tolerant and sensitive Glioblastoma cells remains unresolved. Further studies at the single cell level are needed to reveal transient and long-term signatures of the resistant states.

MATERIAL AND METHODS

To investigate long-term phenotypic changes upon treatment at the single cell level we performed single cell RNA-seq (scRNA-seq) on the longitudinal patient-derived xenograft (PDOX) models derived from Glioblastoma patient tumors prior and after the standard-of-care treatment. In addition, direct treatment of PDOXs with temozolomide combined with scRNA-seq allowed revealing short-term transcriptomic changes both in tumor cells and in the mouse-derived cells forming tumor microenvironment. Advanced computational algorithms, including reference-free deconvolution methods, were applied to reveal treatment resistance signatures and master regulators of the identified treatment-resistant subpopulations.

RESULTS

We show that PDOX models recapitulate all the major cell types and transcriptional programs reported in Glioblastoma patient samples, providing clinically relevant models for investigating treatment resistance signatures of tumor cells and associated tumor microenvironment. Analysis of treatment naïve and treated Glioblastomas at the single cell level revealed presence of pre-existing treatment resistant states as well as newly established resistant subpopulatons. Certain transcriptomic changes are preserved long term, regardless of the lack of genetic evolution of the tumor cells.

CONCLUSION

Phenotypic plasticity is an important factor contributing to resistance mechanisms in Glioblastoma. Key molecular regulators of tumor cell plasticity towards treatment resistance states represent novel targets for future combinatory treatments.
PL02.4.A Chromosome 1p19q codeletion frequency, but not survival, varies according to the IDH mutation subtypes: analysis of 1050 IDH-mutated diffuse gliomas
Authors: Picca A , Berzero G , Di Stefano A , Trabelsi N , Bielle F , Sanson M
Published: September 2021

BACKGROUND

recurring hotspot mutations in isocitrate dehydrogenase (IDH) 1 enzymes, and to a lesser extent IDH2, are the main oncogenic alteration in most of lower-grade diffuse gliomas and a subset of grade 4 gliomas. Although most commonly represented by the IDH1R132H mutation, non-canonical IDH1/2-nonR132H mutations are present in about 10% of cases. As the neomorphic enzymatic activity can vary depending on the type of the hotspot mutation, a different biological behaviour may be inferred. Nevertheless, the prognostic significance of the different IDH1/2 mutations remains a matter of debate.

MATERIAL AND METHODS

we queried the OncoNeuroTek tumor bank (Pitié-Salpêtrière Hospital, Paris) to identify all registered cases of IDH-mutated diffuse gliomas. Most relevant clinical and molecular data were collected.

RESULTS

We identified 1050 IDH mutated diffuse gliomas (481 grade 2 [46%], 459 grade 3 [44%], and 110 grade 4 [10%]), of which 1007 (96%) were IDH1 mutated (934 IDH1R132H [89%] and 73 IDH-nonR132H [7%]) and 43 (4%) were IDH2 mutated (24 IDH2R172K [2%] and 19 IDH2-nonR172K [2%]). The chromosomes 1p/19q codeletion was more frequent in IDH2-mutated tumors (25/42 [60%] versus 350/918 [38%] in IDH1-mutated cases, p=0.005). Nevertheless, only IDH2R172K mutation was associated with the codeletion (18/24 [75%], versus 7/18 [39%] in IDH2-nonR172K-mutated tumors, p=0.02). IDH1-nonR132H tumors showed the lowest rate of 1p/19q codeletion (9/69 [13%], versus 341/849 [40%] in IDH1R132H-mutated cases, p<0.001). At the time of observation, 536 patients were deceased (51%), with a median overall survival (OS) of 115 months (mo., 95% CI 108–125 mo.). Median follow up for censored patients was 77 mo. Codeleted patients had a significantly longer OS compared to non-codeleted ones (179 vs. 96 mo., p<0.001). No significant differences in survival were seen when stratifying according to IDH mutation type (115 mo. for IDH1R132H vs. 136 mo. for IDH1-nonR132H vs. 112 mo. for IDH2R172K vs. 150 mo. for IDH2-nonR172K, p=0.8). No differences were seen when restricting the analysis to codeleted or not-codeleted patients only, respectively. In a multivariate analysis including the main prognostic factors (age, sex, preoperative performance status, tumor grade, surgical resection, midline location, 1p/19q codeletion, and p16 homozygous deletion), no survival difference was associated with any of the IDH mutation subtype.

CONCLUSION

although significantly different rates of 1p/19q codeletion were seen according to the four main IDH mutation subgroups, these groups does not associate with different survival profiles in our cohort.
KS01.6.A Comparative analysis of the immune compartment in human glioblastoma and IDH-mutant WHO grade 4 astrocytoma reveals profound differences in microglia phenotypes
Authors: Sankowski R , Friedrich M , Bunse L , Heiland H H , Platten M , Prinz M
Published: September 2021

BACKGROUND

Glioblastoma (GBM) are the most common primary brain tumors. If untreated the average survival is around 12–18 months. Unfortunately, despite extensive research efforts, the therapeutic options remain limited. One major aspect complicating therapeutic development is an immunosuppressive tumor microenvironment. Isocitrate dehydrogenase (IDH)-mutant, WHO grade 4 astrocytomas appear histologically indistinguishable from GBM, but show significantly longer survival times. IDH mutations lead to changes in the tumor microenvironment with accrual of the neometabolite R-2-hydroxyglutarate. Previous studies on bulk transcriptomes have shown differences in the immune compartment of both tumor entities that were linked to the differences in clinical behavior.

MATERIAL AND METHODS

We have conducted high-dimensional comparative analyses of the myeloid compartment in surgically resected human GBM and IDH-mutant WHO grade 4 astrocytomas using single-cell RNA-Sequencing and immunohistochemistry. Histologically normal brain regions from epilepsy patients were used as controls. For analysis, whole-cell suspensions were prepared from freshly resected tumors or controls. Fluorescence activated cell sorting was used for myeloid cell enrichment. Samples were processed using the high-sensitivity single-cell RNA sequencing protocol CEL-Seq2. Seurat and StemID2 algorithms were used for clustering, differential gene expression and pseudotime analysis. Protein validation was achieved using immunohistochemistry.

RESULTS

We identified profound transcriptional changes of glioma-associated microglia in GBM with respect to control brain samples. Namely, we observed a global upregulation of major histocompatibility complex associated genes in GBM across all clusters. Additionally, we identified distinct myeloid subsets with phagocytic, hypoxia-associated and chemotactic transcriptomic signatures. Pseudotime analysis finely resolved transitional cell states. These changes were dramatically attenuated in IDH-mutant WHO grade 4 astrocytomas. The myeloid cells in these tumors resembled homeostatic microglia and showed an increased expression of cytokine and chemokine genes.

CONCLUSION

Here, we present a high-dimensional transcriptomic atlas of the myeloid compartment in human GBM and IDH-mutant WHO grade 4 astrocytomas. The identified differences point towards targeted therapeutic options via the modulation of the tumor microenvironment.
OS05.9.A Short-term fasting in glioma patients - Analysis of diet diaries and metabolic parameters of the ERGO2 trial
Authors: Voss M , Wenger K J , von Mettenheim N , Bojunga J , Vetter M , Diehl B , Gerlach R , Ronellenfitsch M W , Franz K , Harter P N , Hattingen E , Steinbach J P , Rödel C , Rieger J
Published: September 2021

BACKGROUND

The prospective, randomized ERGO2 trial investigated the effect of fasting / calorie restricted ketogenic diet (KD-IF) on re-irradiation for recurrent brain tumors (Clinicaltrials.gov number: NCT01754350). The study did not meet its primary endpoint of improved progression-free survival in comparison to a standard diet (SD). We here report the results of the quality of life questionnaire, neurocognition testing, detailed analysis of the diet diaries and the alterations of metabolic parameters.

MATERIAL AND METHODS

50 Patients were randomized 1:1 to re-irradiation combined with either SD or KD-IF. The KD-IF schedule included 3 days of ketogenic diet (KD: 21–23 kcal/kg/d, carbohydrate intake limited to 50 g/d), followed by 3 days of fasting and again 3 days of KD. Follow-up included examination of cognition, quality of life and serum samples.

RESULTS

The 20 patients who completed KD-IF met the prespecified goals for calorie and carbohydrate restriction. In these, a decrease in leptin and insulin and an increase in uric acid was observed. The SD group had a lower calorie intake of 21 kcal/kg/d than the expected 30 kcal/kg/d. Neither quality of life nor cognition were affected by the diet. Low glucose emerged as a significant prognostic parameter in a best responder analysis.

CONCLUSION

The strict caloric goals of the ERGO2 trial could be achieved by patients with recurrent brain tumor. The unexpected lower calorie intake of the SD group might have hampered the interpretation of the trial. However, the short diet schedule already led to significant metabolic alterations, suggesting that short-term dietary interventions might be therapeutically useful, possibly combined with other modalities.
OS10.8.A The effectiveness of antiepileptic drug duotherapies in glioma patients: a multicenter observational cohort study
Authors: van der Meer P B , Dirven L , Fiocco M , Vos M , Kouwenhoven M C M , van den Bent M J , Taphoorn M J B , Koekkoek J A F
Published: September 2021

BACKGROUND

About 30% of glioma patients need an add-on antiepileptic drug (AED) due to uncontrolled seizures on AED monotherapy. This study aimed to determine whether levetiracetam combined with valproic acid (LEV+VPA), a commonly prescribed duotherapy, is more effective than other duotherapy combinations including either LEV or VPA in glioma patients.

MATERIAL AND METHODS

In this multicenter retrospective observational cohort study, treatment failure (i.e. replacement by or addition of a new AED, or withdrawal of an AED) for any reason was the primary outcome. Secondary outcomes included: 1) treatment failure due to uncontrolled seizures; and 2) treatment failure due to adverse effects. Time to treatment failure was defined as the time from the start of AED duotherapy until the time of treatment failure. Multivariable Cox proportional hazard models were estimated to study the association between risk factors and treatment failure. The maximum duration of follow-up was 36 months.

RESULTS

A total of 1435 patients were treated with first-line monotherapy LEV or VPA, of which 355 patients received AED duotherapy after they had treatment failure due to uncontrolled seizures on monotherapy. LEV+VPA was prescribed in 66% (236/355) and other AED duotherapy combinations including LEV or VPA in 34% (119/355) of patients. Patients using other duotherapy versus LEV+VPA had higher risk of treatment failure for any reason (cause-specific hazard ratio [csHR]=1.50 [95%CI=1.07–2.12], p=0.020), treatment failure due to uncontrolled seizures (csHR=1.73 [95%CI=1.10–2.73], p=0.018). There were no differences in failure due to adverse effects (csHR=0.88 [95%CI=0.47–1.67]), p=0.703) between the two groups.

CONCLUSION

This observational cohort study suggests that LEV+VPA has better efficacy than other AED combinations. Similar toxicities were experienced in the two groups.
OS14.4.A The Neuroplastic Potential of the Human Brain before and After Glioma Surgery: Towards “Interventional Neurorehabilitation
Authors: Poologaindran A , Romero-Garcia R , Hart M , Young I , Santarius T , Price S , Sinha R , Profyris C , Profyris C , Erez Y , Teo C , Sughrue M , Suckling J
Published: September 2021

INTRODUCTION

The human brain is a highly neuroplastic ‘complex’ network: it self-organises without a hard blueprint, adapts to evolving circumstances, and can withstand insults. However, similar to other naturally occurring networks, brain networks can only endure a finite amount of damage before cognitive processes are affected. In this study, we first sought to establish the brain networks governing domain-general cognition (DGC) in healthy individuals across the lifespan. We then sought to map, track, and potentially rehabilitate networks governing DGC through connectomics and non-invasive brain stimulation (NIBS) when damaged by low-grade gliomas (LGG) and surgical oncology.

METHODS

Using MRI and cognitive data from n=629 individuals (aged 18–88, Female= 51%), we assessed the structural, functional, and topological relevance of the spatially-distributed multiple-demand (MD) system for DGC. Next, in n=17 patients undergoing glioma surgery, we longitudinally acquired connectomic and cognitive data at multiple time points: pre-surgery and post-surgery Day 1, Month 3, Month 12. In an independent cohort of n=34 patients, we sought to establish the safety profile for “interventional neurorehabilitation”: connectome-driven NIBS in the acute post-operative period to accelerate cognitive recovery.

RESULTS

In healthy individuals, the MD system across multiple scales of biological organisation was positively associated with higher-order cognition (Catell’s fluid intelligence). In our patients, pre-operative LGG infiltration into the structural MD system was negatively associated with the number of long-term cognitive deficits, suggesting a functional reorganisation. Mixed-effects modelling demonstrated the resilience of the functional MD system to infiltration and resection, while the early post-operative period was critical for effective neurorehabilitation. Graph analyses revealed increased perioperative modularity can distinguish patients with long-term cognitive improvements at one-year follow-up. Finally, NIBS within two weeks post-craniotomy had a 90% (n=31/34) recruitment rate into the trial. There were no seizures or serious complications due to NIBS in this patient population. Transient headaches and tingling were reported in a minority of patients.

CONCLUSION

For the first time, we elucidate long-term cognitive and network trajectories following LGG surgery while establishing a positive safety-profile for NIBS in the acute post-operative period. We argue that “mesoscale” brain mapping serves as a robust biomarker for intervention-related plasticity for future clinical trials. While we performed these experiments in the context of neurosurgery, connectomics and NIBS could be adopted across diverse neuro-oncological care pathways (i.e. chemotherapy/radiation).
OS14.6.A GlioCova: Defining patient safety events for brain tumour patients undergoing neurosurgery
Authors: Mauricaite R , Le Calvez K , Brodbelt A , Bottle A , Williams M
Published: September 2021

BACKGROUND

Surgery is associated with a risk of adverse events (e.g. venous thrombosis). These have been used to define the OECD Patient Safety Event (PSE) indicators (41 diagnostic codes), but not in the brain tumour population. The GlioCova project uses English linked national cancer data on all 51,775 adult primary brain tumour patients (2013–2018).

MATERIAL AND METHODS

We identified all glioblastoma patients having surgery for their tumour and noted the 100 most common ICD-10 diagnostic codes within 30 days of surgery, excluding previous medical conditions, brain tumour diagnosis codes and OECD-defined codes. Potential post-surgical complications were reviewed by a group of experienced clinicians. We reviewed these “novel PSE codes” in all brain tumour patients re-admitted after surgery. We looked at the co-occurrence between our novel and OECD codes and combined them to form the final PSE list.Patients readmitted within 30 days were divided into those without codes (“PSE-free”), and those with at least one PSE code during admission or readmission. We examined age, length of stay, in-hospital and 30-day mortality and assessed statistical significance using Welch’s t-test and a two sample Z-test for proportions.

RESULTS

29,135 patients underwent neurosurgery, of whom 8,361 (28.7%) were readmitted within 30 days. We identified 32 novel PSE codes. 1,319 (16%) patients had an OECD code, 5,524 (66%) had a novel code, and 2,098 (25%) patients were PSE-free. 83% of patients who had an OECD PSE code also had a novel code. Patients in the PSE group were older (median age = 60 years) than the PSE-free group (57 years). Length of stay was longer in patients who had a PSE after surgery (median = 7 days) and after readmission (5 days) compared with PSE-free after surgery (4 days), at readmission (0 days). More patients died in hospital after readmission in the PSE group (4.7%) compared with no-PSE (2.7%). 30-day mortality after surgery was similar in both groups (2.5% PSE-free, 3.1% PSE group). All differences were highly statistically significant (p<0.0001).

CONCLUSION

We identified 32 novel patient safety event codes following surgery in the brain tumour population. Patients with these diagnostic codes had an elevated LOS and in-hospital death rate. Using brain tumour specific PSE codes captures many more events than the existing list of OECD codes.
P04.02 Single-cell transcriptomic analysis reveals shifts in glioblastoma cell composition in different BMP4-treated primary tumor cultures
Authors: Verploegh I S C , Conidi A , Brouwer R W W , van IJcken W F J , Lamfers M , Leenstra S , Huylebroeck D
Published: September 2021

BACKGROUND

Glioblastoma (GBM) is the most aggressive primary brain tumor. The well-known cellular heterogeneity of this cancer, which includes glioma tumor-initiating cells with stem cell characteristics (GSCs), (co)influences therapy resistance and tumor recurrence. Bone Morphogenetic Protein-4 (BMP4) promotes differentiation of GSCs towards astroglial lineage while suppressing oligodendrocyte maturation. Treatment with BMP4 is associated with increased survival in mice. BMPs exert effects in cell-type and context dependent fashion, but also generate subtle heterogeneity in transcriptional response among similar cells. We studied first the cell viability of BMP4-treated primary GBM cultures followed by single-cell RNA-sequencing (scRNA-seq) on two differently responding cultures, and found correlation between their responses and therapy sensitivity.

MATERIAL AND METHODS

Cell viability, proliferation and apoptosis were assessed in 17 patient-derived BMP4-treated GBM cell cultures. We selected one culture in which this treatment induced high in vitro therapeutic efficacy, and one in which the treatment was ineffective, for analysis by scRNA-seq and then compared the results on the initial panel of 17 cultures.

RESULTS

After 7 days of treatment with BMP4, cell viability ranged from 28% (referred to as highest in vitro therapeutic efficacy) to 132% compared to untreated cells. scRNA-seq of the previously mentioned cultures in passage 7 showed that all neural cell types that are usually found in freshly resected GBM, were also present in our cultures. In the culture where BMP4 induced high in vitro therapeutic efficacy, BMP4 induces the formation of a large new cell population displaying decreased cell proliferation, increased migration and cell death, while the pro-inflammatory cells were depleted. RNA-velocity analysis revealed that, the cycling of cells was greatly diminished in the culture where therapy with BMP4 was efficacious, whereas this was enhanced in the GBM culture with the lowest cell viability after treatment. Astroglial differentiation was induced in all BMP4-treated cultures, while neuronal differentiation was reduced most in the cultures in which BMP4 induced lower or no in vitro therapeutic efficacy. In the culture without therapeutic efficacy of BMP4 cell cycle arrest was not induced anymore. In addition, OLIG1/2 mRNA and protein levels seemed predictive for BMP4-therapy efficacy, while activation of translation-associated genes (RPL27A, RPS27) was a suitable, immediate post-therapeutic marker for this.

CONCLUSION

scRNA-seq of in vitro GBM cultures provides advanced insights into the mechanism underlying therapy efficacy of BMP4. Neural differentiation status is distinctive for therapeutic efficacy of BMP4 in vitro before and after therapy.
P04.03 Different role of integrin a6 in glioblastoma proneural and mesenchymal stem-like cells
Authors: Stanzani E , Pedrosa L , Bourmeau G , Anezo O , Noguera-Castells A , Passoni L , Núria N , Seano G , Tortosa A , Martinez-Soler F
Published: September 2021

BACKGROUND

The plasticity of tumoral cells and the presence of cells displaying stem-like features are two interrelated traits of Glioblastoma (GBM) lesions and both concur in defining its heterogeneity. Particularly, GBM stem-like cells (GSC) can be classified according to trascriptional data in different subgroups, being the Proneural (PN-GSC) and the Mesenchymal (MES-GSC) the most consolidated clusters. GSC are responsible of most of the malignant characteristics of GBM, including therapeutic resistance and tumor recurrence. Therefore, a better understanding of the mechanisms regulating GSC responsiveness to therapy taking into account GSC molecular heterogeneity may help to improve patient’s outcome. Integrin a6 is a commonly used marker for GSC capable to enrich for GSC population and sustain stemness. We investigate the role of integrin a6 in both PN and MES GSC on stemness and radioresistance.

MATERIAL AND METHODS

The expression of integrin a6 was analyzed in GSC cultures obtained from post-surgical specimens either displaying PN or MES trascriptional traits. Using cell sorting to enrich for integrin a6 expression (integrin a6-high and a6-low) and gene silencing with lentiviral-based shRNA, integrin a6 impact on both GSC cultures was tested. Also, silenced MES-GSC were analysed by means of RNA-seq. The major pathways found altered by integrin a6 silencing were validated at functional level using gliomasphere-based clonogenic assay, extreme limiting dilution assay and gamma-H2AX to monitor DNA damage repair kinetics.

RESULTS

After sorting GSC cultures by integrin a6 expression, PN-GSC a6-low showed a significant reduction in clonogenic capability and gliomasphere size when compared to a6-high (p<0.0001). On the contrary, sorted MES-GSC did not display any differences. Similar results were obtained following integrin a6 lentiviral silencing. However, RNAseq on silenced MES-GSC revealed a significant impact on cell cycle regulation and DNA damage repair pathways. Indeed, Integrin a6 trascriptional inhibition in MES-GSCs impaired the capacity to clear gamma-H2AX foci after ionizing radiation (p<0.001) and significantly alters MES-GSC capacity to recover from radiation treatment in gliomasphere formation assay (p<0.01). According to the interpretation of the curves with the linear quadratic model, integrin a6 silenced cells displayed higher alpha- and beta- values and lower alpha/beta ratio. The obtained values demonstrate increased radiosensitivity and impaired capacity to repair sublethal DNA damage, in addition to an enhanced sensitivity to fractionated doses.

CONCLUSION

The data obtained showed that Integrin a6 regulates proliferation and stemness-related features in PN-GSC while supports radioresistance of MES-GSCs. Altogether, we reveal that integrin a6 controls different stem-associated features in GSCs depending on the molecular subtype.
P04.05 Targeted Gene-Expression analysis during malignant transformation in primary and secondary malignant meningioma
Authors: Maier A D , Meddis A , Haslund-Vinding J , Mirian C , Areskeviciute A , Nguyen P , Westergaard C , Melchior L C , Munch T N , Skjøth-Rasmussen J , Poulsgaard L , Ziebell M , Bartek Jr J , Broholm H , Poulsen F R , Gerds T A , Scheie D , Mathiesen T
Published: September 2021

BACKGROUND

Malignant meningiomas comprise 2–5% of all meningiomas. The process of malignant transformation when benign meningiomas (WHO grade I-II) become malignant (WHO grade III) has not previously been investigated in sequential tumour surgeries. Upregulation of FOXM1 expression and DREAM-complex repression have shown phenotypical subgroups correlating with WHO grade and aggressiveness. We investigated the RNA expression of 30 genes central to meningioma biology and 770 genes involved in neuroinflammatory pathways in primary and secondary malignant meningioma patients who underwent one to several operations.

MATERIALS AND METHODS

We identified a cohort of consecutive malignant meningioma patients treated at Rigshospitalet, Copenhagen from 2000–2020 (n=51) and gathered their malignant tumours and previous WHO grade I/II tumours. The malignant cohort (MC) was counter matched with a benign cohort (BC) where patients had no recurrences during follow-up. RNA expression signatures from 140 samples from the MC and 51 samples from the BC were analysed with the Nanostring Neuroinflammation panel customized with 30 genes known to be relevant in meningioma phenotypes.

RESULTS

49% of MC patients had a previous grade I/II meningioma making them secondary malignant meningioma patients. Progression-free survival calculated from first malignant surgery to first recurrence or death showed no significant difference in the primary vs. secondary patients. Preliminary results of single-gene analysis of MC tumours showed FOXM1, MYBL2, TOP2A, BIRC5 expression was higher in WHO grade III samples. Gene-expression signatures in the individual patients and gene ontology enrichment analyses are in process.

CONCLUSIONS

FOXM1, MYBL2, TOP2A, BIRC5 RNA expression levels seem to rise during malignant progression across patients. Gene-expression analysis using the Nanostring technology is feasible and a potentially powerful tool to distinguish meningiomas prone to malignant transformation from truly benign meningiomas.
P04.11 10-Year Institutional Retrospective Case Series of WHO Grade II Gliomas and Correlation of Seizures, Lobar Location, Histopathological Subtype and IDH-1 Mutation (2010–2020)
Authors: Lammy S , Bridgman E , Johnson H , Taylor A , Grivas A
Published: September 2021

BACKGROUND

A 10-year retrospective case series was undertaken of all patients who had a tissue diagnosis of a World Health Organisation (WHO) Grade II glioma, i.e. low grade glioma (LGGM), at the Institute of Neurological Sciences (INS) between January 2010 and January 2020 (NB: pre-2016 World Health Organisation classification). The objective was to assess the correlation of World Health Organisation (WHO) Grade II gliomas to seizure symptomology, intracerebral tumour location, histopathological glioma sub-type and molecular markers including isocitrate dehydrogenase-1 (IDH-1) mutation.

MATERIAL AND METHODS

We extracted data regarding clinical, radiological, histological, molecular discriminators and functional outcomes in patients. The pre-operative symptomology was restricted to seizures, headache and focal neurological deficits.

RESULTS

84 patients underwent resection and had a mean age of 42rs (range: 21-77yrs]). Seizures (NB: pre-2017 International League against Epilepsy classification [ILAE]) occurred in 71% and of these 52% were generalised, 37% partial and 11% mixed. 31% had ongoing seizures postoperatively. Headache occurred in 38% (of these 50% had headache and seizures). Focal neurological deficits (FNDs) occurred in 21% (of these 61% had FNDs and seizures). Seizure, as an isolated pre-operative symptom occurred in 48% patients compared to isolated headache in 10% and isolated FNDs in 4%. Anatomically, 58% of lesions were frontal. The seizure spatial frequency was 60% frontal. Histologically, 60% were diffuse astrocytomas and 40% oligodendrogliomas. Furthermore, 71% of oligodendrogliomas and 49% of diffuse astrocytomas had a frontal location. IDH-1 mutation occurred in 80% patients (75% of these had seizures) and of these 66% were frontal.

CONCLUSIONS

Our analysis confirms a correlation between incidence of seizures, frontal lobar location, histopathological subtype and IDH-1 mutations (p = <0.05
P05.04 Reradiation by reccurent gliomas with VMAT (Volumetric Modulated Arc Therapy) technique- survival benefit
Authors: Theodorou M , Polycarpou I
Published: September 2021

BACKGROUND

Patients who have been treated with reirradiation for recurrent glioma reported survival benefits. Limited data are available for the outcomes after fractionated re-irradiation.

This study aims to investigate whether re-irradiation of recurrent glioma with 45Gy dose can increase the overall survival of patients.

MATERIAL AND METHODS

A retrospective analysis of 35 patients re-irradiated for high-grade glioma recurrence between 2012 and 2020 was performed. All included patients met the following criteria: a) histopathological confirmation of primary brain cancer at initial diagnosis; b) a history of initial primary radiation; c) histological and/or imaging modality confirmation of recurrence. Outcome metrics included overall survival, prognostic factors for survival, and treatment-related toxicity.

RESULTS

After the end of re-irradiation the median overall survival was 11 months (95% confidence interval, 7–14 months). From the patients evaluated in the current study after the end of re-irradiation the progression free survival was 6 months (3.8 - 8 months) while after the end of first radiation was 13 months (8 - 17.9 months). Our findings suggest that re-irradiation might prolong survival rates.

CONCLUSION

Recurrent Glioblastoma WHO IV is associated with a median overall survival of less than a year and the majority of patients have profound tumor-related symptoms.The results of this study suggest that re-irradiation may prolong the overall survival.
P06.03 Child, parent, and clinician selection of patient-reported outcome measures to use in pediatric neuro-oncology outpatient follow-up clinics
Authors: Bull K S , Stubley S , Freeman A , Liossi C , Darlington A E , Grootenhuis M A , Hargrave D , Morris C , Walker D A , Kennedy C R
Published: September 2021

BACKGROUND

Survivors of childhood brain tumours are at risk of poor health-related quality of life (HRQoL). Appropriate and relevant measures can be used to monitor HRQoL so that timely interventions may be made for issues thus identified. We had previously selected patient-reported outcome measures (PROMs) with good psychometric properties that had emerged as well-suited for this use in two systematic reviews. The aim of the present study was to ascertain the views of families regarding the suitability of the selected measures for use in paediatric neuro-oncology follow-up clinics. These views were then used to inform the choice of PROMs for use on the KLIK PROM portal, a website designed to gather HRQoL information from families.

MATERIAL AND METHODS

As part of the PROMOTE study, we used a multi-centre, multi-informant, cross-sectional, qualitative methods research design. Using ‘think aloud’ audio-recorded interviews, children aged 8–17 years diagnosed within the previous five years with a brain tumour, off treatment and receiving outpatient care, and their parents, were shown a total of nine PROMs and asked to express their views on which they preferred. Detailed notes were made of all audio-recordings by two independent researchers. The final choice of PROMs to be included on the KLIK PROM portal was agreed through discussion of the PROMs selected by families with an expert panel of clinicians, researchers, and parent representatives.

RESULTS

16 children and 17 parents participated and of these 2 children and 2 parents did not express a preference. The Pediatric Quality of Life Inventory (PedsQL) Core module was the most popular among the children and parents with 7/14 (50%) of children selecting it as either their 1st or 2nd choice citing that they liked the questions and felt them to be most relevant to them, and 8/15 (53%) of parents citing that it was easy, quick and simple, the wording was easy, and they liked the questions about emotional, social, and school functioning. The least popular questionnaires, with no participants selecting them as first choices, were the Kidscreen-10 and the Health Utilities Index. The latter 2 were selected only as 2nd or lower choices by 1 child and 3 parents respectively.

CONCLUSION

The PROMs that were finally selected for the KLIK PROM portal were the parent- and child-report PedsQL-Core measures of HRQoL due to their good psychometric properties, family and clinician preference and perceived relevance to follow-up care, and for clinical utility on the KLIK PROM portal.
P09.05 Treatment strategy of MRI postcontrast non-enhanced gliomas
Authors: Kalita O , Hrabalek L , Jan V , Slachta M , Klementová Y , Dolezel M , Cechakova E , Drabek J , Hajduch M , Hok P , Hlustik P , Tuckova L , Halaj M , Vrbkova J
Published: September 2021

BACKGROUND

MRI postcontrast nonenhanced brain tumors are found benign biologic entities with the better prognosis. The aim of this paper is to evaluate predictive features on MRI considered definite diagnosis occurrence, tumor progression, upgrading and postcontrast enhancement evolution on follow-up serial MRI.

MATERIAL AND METHODS

We retrospectively collected patients with the initially MRI postcontrast nonenhanced brain tumors, treated in our hospital from January 2009 to June 1, 2006. All tumors were converted into WHO 2016 IDH status classifications in accordance with current recommendations. Information about surgeries, patient clinical condition, MRI, and results of histological, immunohistochemical, molecular genetic, and cytogenetic investigations were gathered. Semiautomatic segmentations were performed using FSLeyes software (part of FSL package) on preoperative and followed-up 3D T1-w MPRAGE, T2-w or FLAIR scans. We focused on residual tumor volume, and time distribution of T2/FLAIR changes and T1-w postcontrast enhancement evolution.

RESULTS

Seventy-eight patients were enrolled in this study. There were 47 gliomas grade II 22 grade III and 9 grade IV. Glioma II comprised 35 diffuse astrocytomas (23 patients had IDH1 mutation). Nine gliomas grade III and 6 gliomas grade IV had IDH1 mutation. Overall survival in glioma group grade II, grade III, grade IV was 187.9 months, 71.1 months and 25.2 months, respectively. Oncotherapy underwent 14 gliomas grade II after first surgery, 13 patients had radiotherapy a 1 patient had neoadjuvant chemotherapy. Seventeen gliomas grade III were indicated to oncotherapy, 5 patients had radiotherapy and 12 had chemoradiotherapy. All patients with glioma grade IV experienced oncotherapy. Time to progression of non-contrast enhanced brain tumor was 5.8 years. Time to up-grading of non-contrast enhanced brain tumor was 16.8 months. Detailed time relations of glioma subgroup will be displayed in tables.

CONCLUSION

Regarding MRI postcontrast non-enhanced tumors, predominantly low grade gliomas (LGG), aggressive oncotherapy are reluctant to use but they are prone to repeat surgeries. Decision making issues are age, clinical patient status, histologic and genetic tumor characteristics, residual tumor volume, published guidelines for brain tumor treatment, and patient′s willing. Generally, hyposignal on the T1 postcontrast scans strictly relate to the better prognosis, even in HGG. Longer survival expectancy increases quality of life awareness. Prior to MRI postcontrast enhanced evolution and up-grading, T2/FLAIR changes have been demonstrated. T2/FLAIR scans considered also main role in LGG follow-up strategy. Individual tailored therapy is principal strategy.

Supported by Ministry of Health of the Czech Republic, grant nr. NV19-04-00281 and grant nr. NU21-03-00195
P12.04 Body Mass Index: a possible PICC-related complications risk factor in neuro oncological patients
Authors: Simonetti G , Gaviani P , Botturi A , Redaelli V , Anghileri E , Silvani A
Published: September 2021

BACKGROUND

The use of central venous catheter with peripheral insertion (PICC) has increased rapidly in recent years particularly in cancer patients because they represent a stable and safe vascular access to administer irritants or vesicants therapies. However, the benefit provided may occasionally be affected by severe complications. An observational study conducted at our Institute, showed a significant increase of thromboembolic risk in neuro-oncological patients compared to general cancer population (16.3% vs 6.7% respectively). For this reason, it is essential to identify independent risk factors in order to avoid preventable harm.

MATERIAL AND METHODS

Neuro-oncological patients with PICC that developed a thromboembolic event were retrospectively analyzed. We evaluated clinical data, BMI, KPS, steroid therapies and anticoagulants at the time of positioning of the PICC and at the onset of the thrombotic event.

RESULTS

A total of 90 neuro-oncological patients have been analyzed. The most common histology was represented by glioblastoma, followed by anaplastic astrocytoma, primary central nervous system lymphoma, grade II glioma. 17.6% of patients were at first diagnoses, 41.6% were at the first recurrence, and the remaining patients were at the second or third recurrence. The median KPS was 90 (range 80–100), and the median ECOG was 0 (range 0–2). Overall, 14% patients developed thromboembolic events within a median time of 34.5 days (range 5–146) after PICC implantation. Among these, 64% of patients was considered overweight. No patients were on anticoagulant therapy but all were treated with a median dose of 5.5 mg of steroids (range 3,5-12), stable between PICC insertion and onset of adverse event.

CONCLUSION

64% of patients who developed a thromboembolic event had BMI >28 at the time of PICC insertion, suggesting a possible trend towards a risk of developing PICC related thrombosis in overweight/obese patients. Other independent risk factors for PICC associated complications seems to be amount of previous chemotherapies administered: 82% of patients who developed thrombotic complications had already undergone at least one line of chemotherapy before PICC placement, suggesting this condition as a possible risk factor for the onset of the event. Also failed positioning attempts could damage vascular endothelium, contributing to the onset of thrombotic complications. An accurate anamnesis and a physical evaluation with particular attention to the presence of malnutrition could help in the in the early identification of independent risk factors that could farther negatively influence the outcome of neuro-oncological patients.
P12.07 The potential of cannabinoids to improve quality of life in glioma patients: A meta-analysis in patients with neurological and oncological disease
Authors: Belgers V , Röttgering J G , Douw L , Klein M , van de Ven P M , Ket J C F , Bacher Svendsen K , Weber M , Lopez-Sendon J , Olde Rikkert M G , Chagas M H N , van Linde M E , Kouwenhoven M C M , de Witt Hamer P C
Published: September 2021

BACKGROUND

Gliomas are primary brain tumors with a dismal prognosis. Reducing symptoms and maintaining quality of life (QoL) are main treatment aims in glioma patients. Mental well-being is an important subdomain of QoL. Cannabinoids have been suggested to alleviate frequently experienced symptoms of reduced mental well-being such as anxiety or depression. Glioma patients frequently report unprescribed cannabinoid use for these reasons. We performed a meta-analysis of the current evidence on cannabinoid efficacy on QoL and mental well-being to identify its added value in treatment of glioma patients.

MATERIAL AND METHODS

We performed a systematic PubMed, Embase and Web of Science search according to the PRISMA guidelines on September 22nd and 23rd, 2020. The effects of any dose of tetrahydrocannabinol (THC) or cannabidiol (CBD) on both general QoL and mental well-being were evaluated. The intervention had to be given for at least a week to establish a steady-state concentration. Effect size was calculated using Hedges g. Risk of bias of included studies was assessed using Cochrane’s Risk of Bias tool 2.0.

RESULTS

We retrieved no publications on cannabinoids use and QoL in glioma and, therefore, we expanded the search to cannabinoid use in other cancer types and chronic central nervous system (CNS) diseases. Sixteen studies were identified: four in cancer and twelve in CNS disease. Meta-analysis showed no effect of cannabinoids on general QoL (twelve studies in 1,740 patients; g = -0.02, 95% CI -0.11 to 0.07, p = 0.65) and mental well-being (twelve studies in 1,587 patients; g = -0.00, 95% CI -0.15 to 0.14, p = 0.96). Risk of bias was low in five studies, raised some concern in one study and was high in ten studies, mainly due to possible unblinding of patients after psychoactive adverse effects.

CONCLUSION

No studies on the effects of cannabinoids on QoL in glioma patients have been reported. A pooled analysis of studies in oncological patients and patients with CNS disease showed no effect of cannabinoids on QoL or mental well-being. However, studies were clinically heterogeneous and only one small study investigated monotherapy CBD with undecided results. As many glioma patients currently use cannabinoids, and monotherapy CBD has not been sufficiently investigated, future studies are necessary to evaluate its value in this specific population.

SUPPORT/DISCLOSURE

This meta-analysis has been funded by The Anita Veldman Foundation (CCA-2019-2-21).
P13.08 Novel Thioridazine derivates: Antiproliferative and apoptosis-inducing activity on glioblastoma cells in vitro
Authors: Schwab S G , Sarnow K , Alme E , Goldbrunner R , Bjørsvik H , Bjerkvig R
Published: September 2021

BACKGROUND

Although withdrawn from the market due to cardiotoxicity, we have shown that the antipsychotic drug Thioridazine shows chemosensitizing effects in combination with Temozolomide (TMZ) for the treatment of glioblastoma multiforme (GBM). Based on our prior observations, the aim of the presented project was through medicinal chemistry, to design and synthesize new compounds based on Thioridazines tricyclic structure, and to determine their therapeutic potential.

MATERIAL AND METHODS

Fourteen compounds were synthesized where variations were made within the tricyclic side chains. The newly synthesized compounds were screened for therapeutic efficacy with or without TMZ using a WST-1 cell viability assay as well as a real-time imaging system (IncuCyte). Tests were performed on both monolayer cell cultures, as well as on glioma stem cell spheroids (GSC). The therapeutic effects were also studied on human astrocytes (NHA) as well as on rat brain organoids (BO). Annexin V/propidium iodide (PI) double staining followed by flow cytometric analysis was performed after 48 hours of treatment.

RESULTS

Following an extensive screening, we identified two novel compounds (EA01 and EA02) that at concentrations of 4 and 9.5 µM showed a strong cytotoxicity on GBM cell lines (U-87 MG p<0,0001, U251 p<0,0001, LN18 p=0,0004) as well as on glioma stem cells (GSC) (P3 p<0,0001) compared to NHA and BOs respectively. Also, when BOs were confronted with GSC spheres in an invasion assay, a selective cytotoxicity was observed in the GSCs. Mechanistically, we show that both compounds induce apoptosis in the GBM cells. Moreover, intravenous delivery of increasing concentrations of EA01 and EA02 revealed no toxicity in animals at concentrations up to 21 mg/kg.

CONCLUSION

We have developed two new tricyclic therapeutic compounds that show a strong selective cytotoxicity in GBM cells with limited systemic toxicity in animals. Ongoing studies are investigating the therapeutic potential of EA01 and EA02 in orthotopic xenografts in vivo.