bluuebunny/crossref_metadata_2025 huggingface dataset:
P11.41.B The Cost of Inpatient Care For Adult Primary Brain Tumour Patients in England
Authors: Kanso N , Le Calvez K , Mauricaite R , Williams M
Published: September 2022

Background

Primary brain tumours are rare, but are the cause of the most life-years lost of any cancer. Given their poor prognosis, questions about their treatment and care costs are important especially in publicly-funded healthcare systems. There is currently very little robust data on the cost of care for brain tumour patients. Here we present up-to-date estimations of the direct inpatient care costs of all adult primary brain tumour patients in England, with a specific breakdown of costs attributed to cranial glioblastomas and cranial meningiomas, the commonest primary brain tumours.

Material and Methods

GlioCova uses a linked English national cancer data on over 50,000 adult primary brain tumour patients diagnosed between 2013-2018, with data on secondary healthcare activities three months before diagnosis - the last three months of 2012, and follow-up data after diagnosis - up to the last admission of 2019. We examined inpatient care with a breakdown of costs attributed to different treatment types: neurosurgery, chemotherapy and radiotherapy. We used the NHS HRG4+ Reference Costs Grouper 2017/2018 to assign costs matched from the National Schedule of Reference Costs 2017/2018. We converted all values to 2021 using the Health CPI Index.

Results

There were a total of 51,775 adult primary brain tumour patients diagnosed in England in the 6 year period between 2013 and 2018. 48,608 of these were admitted to hospital between the last three months of 2012 and the end of 2019, of which we were able to assign costs to 47,521 patients (98%). Total inpatient costs for the whole brain tumour cohort were over £973 million during the time period (34% attributed to inpatient care for neurosurgery, chemotherapy, and radiotherapy). 14,691 (31%) of patients were diagnosed with a cranial glioblastoma, and 9,501 (20%) of patients were diagnosed with a cranial meningioma. Total inpatient costs were £349 million and £163 million for glioblastoma and meningioma respectively, with 34% again devoted to direct treatment costs.

Conclusion

The estimated direct inpatient care costs for all 51,775 primary brain tumour patients diagnosed in England between 2013 and 2018 were nearly £1 billion (£166 million/year cohort), 2/3 of which was not for direct treatment. This does not include outpatient chemotherapy and radiotherapy costs, other outpatient appointments, patient out-of-pocket costs, primary care, social care, or end-of-life care costs. Future work will examine variation in care and costs and extend the analysis to include outpatients. We hope these data will help make an economic argument for improving care for brain tumour patients. More information on GlioCova: https://blogs.imperial.ac.uk/gliocova/about-gliocova/.
P11.42.A Short course of Bevacizumab for differential diagnosis of tumor progression and radionecrosis or pseudoprogression after brain metastasis SRS
Authors: Nikitin K
Published: September 2022

Background

Despite use of modern MRI techniques (perfusion, spectroscopy, TRAMs, radiomics), PET and SPECT the differential diagnosis of radio-necrosis and tumor progression is still difficult in malignant gliomas and brain metastasis after radiotherapy or radiosurgery. For patients who have enlargement of brain metastasis after radiosurgery we suggest a new strategy to discriminate pseudoprogression and true progression - two intravenous infusions Bevacizumab in 5-7 mg/kg with 2-3 week interval and new contrast MR.

Material and Methods

We present 3 relevant clinical cases, all after LINAC-based SRS for brain metastasis.1st case - 49 y.o. female with ovarian cancer underwent SRS for two small closely seated metastases in temporal lobe, both metastasis had shrunk and remained stable until 34 months after radiosurgery a new asymptomatic contrasting lesion with edema developed on MRI adjacent to one of metastasis. Patient developed no other new brain or extracranial mets, so we proposed radionecrosis, but MR-perfusion data was ambiguous. 2nd case - 67 y.o. female with lung adenocarcinoma underwent SRS (27 Gy in 3 fractions) for solitary brain metastasis. 4 months after SRS metastasis partially regressed, but 4 months later a new contrast enhancement zone appeared on its periphery with edema. 18F-FET PET failed to differentiate recurrence and pseudoprogression. 3d case - 48 y.o. female with breast cancer underwent SRS (27 Gy in 3 fractions) for 3 brain metastases. All mets regressed during the next 7 months, but 3 months later one of them showed significant symptomatic enlargement with edema on MRI. All patients received two intravenous infusions Bevacizumab in 5-7 mg/kg with 2-3 week interval and new contrast MRI (1-2 week after second infusion).

Results

1st case - after two infusions of 6 mg/kg with a 3-week interval new contrasting zone disappeared and did not develop again for at least 6 months (with no chemotherapy), so we confirmed necrosis. 2nd case - substantial regression of pathological MRI changes was noted, which was stable for 3 months, diagnostic for pseudoprogression. 3d case - MRI showed substantial regress of contrasting lesion (diagnostic for necrosis), symptoms also regressed and 1 month later methionine PET showed no active tumor.

Conclusion

Our preliminary data suggest that use of two infusions of Bevacizumab and routine contrast MRI have very promising diagnostic value to rule out tumor growth after SRS of brain metastasis.
P11.46.A Whole exome sequencing identifies novel SLIT2 mutations in primary CNS lymphoma
Authors: Kaulen L D , Erson-Omay E Z , Henegariu O , Karschnia P , Huttner A , Günel M , Baehring J M
Published: September 2022

Background

Whole exome sequencing (WES) data on primary CNS lymphoma (PCNSL) is scarce and correlation with clinical observations is needed to facilitate personalized care. Here we present WES data of six PCNSL and correlate genetic findings with clinical outcome.

Material and Methods

WES was performed on paired blood and tumor DNA samples from six PCNSL patients to a median coverage of 100x (range: 73-135x) and 194x (range: 127-232x), respectively. Selected, novel mutations were validated with Sanger sequencing. Epstein-Barr virus (EBV) status was assessed in tumor tissue. Progression free survival (PFS) and overall survival (OS) were analyzed in our cohort and in an extension cohort from the cBio Cancer Genomics Portal using Kaplan-Meier method and log-rank tests. P values < 0.05 were considered significant.

Results

We found a median of 22 (range: 11-68) somatic copy number variations, 171 (range: 82-298) somatic single-nucleotide variants and 11 (range: 0-22) somatic insertions/deletions per PCNSL. CDKN2A loss, identified in five samples, was the most commonly detected copy number alteration. PCNSL carried mutations in previously described PIM1, MYD88, CD79B or BTG genes. In three PCNSL, we identified novel SLIT2 mutations (p.N63S, p.T590M, p.T732S) clustered around the leucine-rich repeats (LRR) domains. WNT-reporter and NF-kB reporter luciferase assays suggested alterations were loss-of-function variants. SLIT2 mutations were associated with shorter PFS in our cohort and with shorter OS in an extension cohort of 1856 lymphoid malignancies from the cBio Cancer Genomics Portal.

Conclusion

PCNSL harbored previously unknown SLIT2 mutations clustered around domains that are critical for interaction with ROBO proteins. SLIT2 mutations may be predictive of less favorable outcome in PCNSL. Additional clinical and molecular evaluation of these mutations is warranted.
P11.53.B Efficacy and tolerability of regorafenib in pretreated patients with progressive CNS grade 3 or 4 gliomas
Authors: Werner J , Wolf L , Tscherpel C , Bauer E K , Wollring M , Ceccon G , Deckert M , Brunn A , Pappesch R , Goldbrunner R , Fink G R , Galldiks N
Published: September 2022

Background

The phase 2 REGOMA trial suggested an encouraging overall survival benefit in glioblastoma patients at first relapse treated with the multikinase inhibitor regorafenib. Here, we evaluated the efficacy and side effects of regorafenib in a real-life setting.

Material and Methods

From 2018-2021, 30 patients with progressive WHO CNS grade 3 or 4 gliomas treated with regorafenib (160 mg/d; first 3 weeks of each 4-week cycle) with individual dose adjustment depending on toxicity were retrospectively identified. Side effects were evaluated according to the Common Terminology Criteria for Adverse Events (version 5.0). MRI was obtained at baseline and after every second cycle. Tumor progression was assessed according to RANO criteria. After regorafenib initiation, the median progression-free survival (PFS) and overall survival (OS) were calculated.

Results

The median number of treatment lines before regorafenib was 2 (range, 1-4). The majority of patients (73%) had two or more pretreatment lines. At first relapse, 27% of patients received regorafenib. A total of 94 regorafenib cycles were administered (median number of cycles, 2; range, 1-9 cycles). Grade 3 and 4 side effects were observed in 47% and 7% of patients, respectively, and were not significantly increased in patients with two or more pretreatments (P>0.05). The most frequent grade 3 or 4 side effects were laboratory abnormalities (62%). PFS was 2.6 months (range, 0.8-8.2 months), and the OS was 6.2 months (range, 0.9-24 months).

Conclusion

In patients with progressive WHO grade 3 or 4 gliomas, predominantly with two pretreatment lines or more, regorafenib seems to be effective despite considerable grade 3 or 4 side effects.
P11.54.A Factors effecting early diagnosis in neurolymphomatosis
Authors: Egert A , Karschnia P , Huttner A , Baehring J M , Kaulen L D
Published: September 2022

Background

Neurolymphomatosis is defined as infiltration of the peripheral nervous system by non-Hodgkin lymphoma (NHL). Given its rarity, correct diagnosis is often delayed. Here we assessed diagnostic work-up and factors affecting timely diagnosis at a tertiary referral center.

Material and Methods

The quality control database of the Section of Neuro-Oncology at Yale Cancer Center was searched for neurolymphomatosis cases seen between 2000 and 2021. Clinical, radiological and pathological findings were collected. Factors affecting the interval from symptom onset to diagnosis were investigated in univariate analysis using SPSS version 27. P-values <0.05 were considered statistically significant.

Results

We identified 22 cases of neurolymphomatosis (primary n=7, secondary n=15) with secondary disease diagnosed a median of 16 months (range: 4-144) after NHL. Patients presented with painful polyneuropathy (n=16), painless polyneuropathy (n=4), cranial neuropathy (n=3), and autonomic neuropathy (n=1). Diagnosis was nerve biopsy-based (n=11) or resulted from integration of imaging findings (n=11) with NHL history (n=5) or detection of NHL in the cerebrospinal fluid (n=6), respectively. Lesions localized to nerve roots (n=16), peripheral nerves (n=12), plexus (n=10), cranial (n=3) or autonomic (n=1) nerves. Histologically, most cases were classified as diffuse-large B-cell lymphoma (n=18). Median interval from symptom onset to diagnosis was 3 months (range: 1-12). Secondary neurolymphomatosis (p=0.02) and FDG-PET imaging (p<0.01) were associated with an earlier diagnosis.

Conclusion

Diagnosis of neurolymphomatosis requires a high degree of clinical suspicion with subsequent integration of clinical, radiological and pathological findings. FDG-PET, the imaging gold standard, and a known NHL history correlated with an earlier diagnosis.
P11.55.B Postoperative MRI is able to detect an unexpected residual tumor after surgery of brain metastases: experience from 5 specialized centers
Authors: Kiesel B , Kerschbaumer J , Prihoda R , Borkovec M , Thakur S , Mercea P , Feucht D , Steindl A , Berghoff A S , Furtner J , Leitner J , Romagna A , Schwartz C , Stefanits H , Marhold F , Rötzer T , Preusser M , Freyschlag C , Widhalm G
Published: September 2022

Background

Brain metastases (BM) constitute the most common central nervous system tumors. The treatment options of BM consist of surgery, radiotherapy, radiosurgery, chemotherapy, and immunotherapy. Regarding surgery in BM, the extent of resection (EOR) represents a crucial factor for patient prognosis. However, first studies using postoperative MRI demonstrated that an unexpected residual tumor after surgery of BM is not uncommon despite these tumors were considered to be well-demarcated. The aim of this study was thus to investigate in a large cohort including multiple neurosurgical centers the EOR following BM resection, potential risk factors for incomplete resection and postsurgical follow-up data.

Material and Methods

In the current retrospective study conducted at 5 specialized neurosurgical centers in Austria, we included patients with BM resection and available postoperative MRI. The EOR following BM resection was determined by postoperative MRI (complete vs incomplete resection). Additionally, the data on the intraoperative judgement of the EOR of the performing neurosurgeon were collected. Moreover, potential factors for incomplete resection including tumor localization, tumor volume, primary tumor, pattern of contrast media enhancement on imaging and tumor eloquence were investigated. Finally, the rate of local progression of BM after initial surgery was analyzed in the follow-up period and overall survival data were collected.

Results

Altogether, 548 patients with 649 surgically treated BM were included. According to postoperative MRI, complete resection was achieved in 407 (66%) of 649 BM and incomplete resection in 176 (29%) of 649 BM. Misjudgment of the EOR by the neurosurgeon was found in 25% of cases and resulted in an unexpected residual tumor which was evident on postoperative MRI in 122 (22%) BM. Preoperative tumor volume was significantly larger in incompletely resected BM. Moreover, local progression was significantly more common in cases with incompletely resected BM and was also associated with shorter overall survival.

Conclusion

Our data of this study including multiple centers indicate that postoperative MRI is capable to detect a relatively high rate of unexpected residual tumors following resection of BM. Since local progression was more common in BM with residual tumors and this was associated with shorter survival, special attention should be paid to achieve a complete tumor resection.
P11.63.B Thrombocytopenia limits the feasibility of salvage lomustine chemotherapy in recurrent glioblastoma: a secondary analysis of EORTC 26101
Authors: Le Rhun E , Oppong F B , Gorlia T , Weller M
Published: September 2022

Background

Chemotherapies used for the treatment of primary brain tumors frequently induce hematological toxicity. Thrombocytopenia represents the main cause of stopping chemotherapy for toxicity. Here we explored the incidence, and the consequences for treatment exposure and survival, of thrombocytopenia induced by lomustine chemotherapy at first recurrence of glioblastoma.

Methods

We performed a retrospective analysis of thrombocytopenia at first recurrence of glioblastoma, its consequences for treatment delivery, and associations with outcome in the phase II and III parts of EORTC 26101, a randomized trial designed to define the role of lomustine versus bevacizumab versus their combination in glioblastoma patients at first relapse.

Results

225 patients were treated with lomustine alone (median 1 cycle) (group 1) and 283 patients were treated with lomustine plus bevacizumab (median 3 lomustine cycles) (group 2). Among cycle delays and dose reductions of lomustine for toxicity, thrombocytopenia was the leading cause. Among 129 patients of group 1 and 187 patients of group 2 experiencing at least one episode of thrombocytopenia, 36 patients in group 1 and 93 in group 2 had their treatment modified because of thrombocytopenia. Lomustine was discontinued for thrombocytopenia in 16 patients (7.1%) in group 1 and in 38 patients (13.4%) in group 2. Patients with O6-methylguanine DNA methyltransferase (MGMT) promoter-methylated glioblastoma treated with lomustine alone experienced more interference with study treatment than patients with tumors without MGMT promoter methylation. On adjusted analysis accounting for major prognostic factors, treatment modification by thrombocytopenia was a positive prognostic factor for overall survival, and this effect was entirely driven by patients with tumors without MGMT promoter methylation only. Conversely, thrombocytopenia was associated with inferior progression-free survival in patients with MGMT promoter-methylated tumors, suggesting a link to insufficient lomustine exposure.

Conclusion

Drug-induced thrombocytopenia is a major limitation to adequate exposure to lomustine salvage chemotherapy in patients with recurrent glioblastoma. Its association with survival suggests that mitigating thrombocytopenia to allow enhanced drug exposure in patients with MGMT promoter methylated tumors might improve outcome.
P11.74.A Plexiform Neurofibromas prevalence and treatment modalities in a referral comprehensive cancer center
Authors: Ferreira M , Costa J , Antão D , Silva E , Passos J , Vilares M , Vasques H , Patrocínio I , Silva C , Santos F , Salgado D , Lacerda M
Published: September 2022

Background

Neurofibromatosis type 1 (NF1) is the most common tumor predisposition syndrome, with an incidence of 1/3500. Plexiform neurofibromas (PN) are benign tumors that can occur along the nerve sheath throughout the body, with unpredictable growth and with risk of malignant transformation. Symptoms will depend on their size and location, and include pain, deformity and functional impairment. There is a great variability in the PN severity and impact on quality-of-life (QOL). An unknown percentage of NF1 patients may need treatment, either medical and/or surgical.

Objectives

To assess the frequency of PN in a NF1 population followed in a comprehensive cancer center.

Material and Methods

Retrospective study. All patients with NF1 and PN followed in our center, between 31/12/2000 and 31/12/2021.

Results

Of 438 NF1 patients, 185 had PN (42%). 52 NF1 patients with PN were children (≤ 18). The most common symptoms were pain in 71 people (38,4%), deformity in 70 (37,8%) and functional impairment in 69 (37,3%). Several patients had a combination of these symptoms. Different treatment modalities were used for PN: medical, surgical or both. In this study, 54 patients (29,1%) were treated with MEK inhibitors (selumetinib), 74 patients (40%) were treated surgically and 12,4% (23) needed a combined approach (medical and surgical treatment).

Conclusion

PN are frequent in NF1 patients. A significant percentage is symptomatic and will require treatment, surgical, medical or both. There is no standard of care for PN NF1. The timing and sequence of medical and surgical treatment is yet to be defined.
P12.06.A Relationship between ascorbate and DNA methylation markers in clinical glioma tumours
Authors: Crake R L I , Burgess E R , Wiggins G A R , Magon N J , Das A B , Vissers M C M , Morrin H R , Royds J A , Slatter T L , Robinson B A , Phillips E , Dachs G U
Published: September 2022

Background

Members of the 2-oxoglutarate-dependent dioxygenase (OGDD) enzyme family play an important role in gliomas as they regulate epigenetic modifications and response to hypoxia. The OGDDs require 2-OG and O2 as substrates, and ferrous iron and ascorbate as cofactors. Both hypoxia and aberrant DNA methylation are prognostic indicators for gliomas. The ten-eleven translocase (TET) DNA demethylases are OGDDs that convert 5-methyl cytosine (5mC) to 5-hydroxymethylcytosine (5hmC), with 5hmC levels related to better prognosis. Despite this, there is limited data on the OGDD enzymes and their substrates/cofactors in glioma tissues. Our previous study showed an association between ascorbate content and markers of the hypoxic response in glioblastoma tissue. Here we determine whether there is an association between ascorbate and DNA methylation in glioma. In addition, we assess whether methylation of the methylguanine-DNA methyltransferase (DNA repair enzyme MGMT) promoter is associated with ascorbate content.

Materials and methods

Frozen clinical glioma samples from 37 patients (n=11 WHO grade I-III, n=26 glioblastoma) were obtained from the Cancer Society Tissue Bank (Ethics approval H19/163). Isocitrate dehydrogenase 1 (IDH1) mutation status was determined by sequencing. Samples were processed on dry ice in liquid nitrogen and analysed for ascorbate (high-performance liquid chromatography), global DNA methylation (mass spectrometry) and MGMT promoter analyses (methylation specific PCR).

Results

Many grade I-III tumours were IDH1 R132H mutant (6/11), and most glioblastomas were not (2/26). Glioblastoma had significantly lower ascorbate content than grade I-III tumours (p=0.026). Glioblastoma also had lower global 5hmC levels (p=0.0013). IDH1 R132H tumours tended to have a lower ascorbate content (p=0.09). Ascorbate and 5hmC levels were directly correlated (Spearman r= 0.466, p=0.004). However, cytosine and 5mC showed no association with grade or ascorbate. MGMT promoter methylation status was not associated with global methylation or ascorbate content (p=0.97, p=0.96, respectively).

Conclusion

Our data suggests that ascorbate supports TET activity in clinical glioma. It also appears that site-specific (promoter) methylation was not affected by ascorbate availability. These findings may have clinical implications, as higher 5hmC levels are associated with improved outcome, whilst continued MGMT suppression suggests chemotherapy responsiveness. However, evidence that raising tumour ascorbate leads to increased 5hmC levels, or an associated improvement in survival, requires intervention trials.
P12.07.B Getting to the core of microglia versus bone marrow-derived macrophages in glioblastoma
Authors: Woolf Z R , Smith A , Swanson M E V , Scotter E L , Schweder P , Correia J , Park T I , Dragunow M
Published: September 2022

Background

Microglia and bone marrow-derived macrophages (BMDMs) are two ontogenetically distinct myeloid populations present within glioblastoma that can comprise 30-50% of the tumour mass. Historically, these cell types have been conflated and studied as a single population of ‘tumour-associated macrophages’. Recent advances in single-cell omics have allowed population delineation, suggesting microglia and BMDMs may play different roles within the tumour and subsequently differentially affect tumour progression. Despite building evidence for the unique functions of these cells within glioblastoma, the inherent heterogeneity of the tumour landscape has complicated such studies. Indeed, macrophages exist as phenotypically and functionally diverse populations that are polarised in a context-dependent manner. Hence, to understand the differences between microglia and BMDMs within glioblastoma, both ontogeny and spatial location must be considered.

Material and Methods

To elucidate the functional roles of microglia and BMDMs across the tumour landscape, a publicly available RNAseq dataset was utilised to classify myeloid cells into four populations based on spatial location and ontogeny. These were tumour core BMDMs and microglia, or tumour periphery BMDMs and microglia. Differential gene analysis was then performed to identify significant differentially expressed genes (DEGs) between classified myeloid populations. Tumour core DEGs were then compared against the Ivy Glioblastoma Atlas to define their expression across anatomical tumour regions. Finally, myeloid DEGs were validated at the protein level on human glioblastoma tissue through immunohistochemistry.

Results

Microglia and BMDMs showed different spatial distributions across the tumour landscape and displayed distinct functional expression profiles. Microglia held a more chemotactic and pro-inflammatory profile, whereas BMDMs held a more pro-tumoural profile. However, a comparison of microglia between the tumour core and periphery revealed that tumour microglia upregulate many pro-tumoural genes, including multiple genes that have previously been defined as ‘BMDM-enriched’. Moreover, we found myeloid DEGs identified within the tumour core cluster to distinct spatial tumour regions such as the vascular or hypoxic niche. Immunohistochemical staining reflected these spatial expression profiles, identifying a distinct population of phagocytic macrophages within the hypoxic niche.

Conclusion

Although microglia and BMDMs represent two ontogenetically distinct myeloid populations within glioblastoma, both cell types can adopt similar functional expression profiles within the tumour core, particularly within tumour niches. This indicates that myeloid cell function is strongly influenced by the tumour microenvironment, rather than ontogeny alone.
P12.10.A Supratentorial glioblastoma with spinal metastasis: a case report with molecular profiling
Authors: Jancalek R , Hendrych M , Solar P , Hermanova M , Slaby O
Published: September 2022

Background

Glioblastoma (GBM) is regarded as an aggressive brain tumor that rarely develops extracranial metastases. Despite well-investigated molecular alterations in GBM, there is a limited understanding of these associated with the metastatic potential of GBM.

Material and Methods

We present a case report of a 43-year-old woman with frontal GBM IDH-wildtype, who underwent gross-total resection followed by chemoradiation. Five months after surgery, the patient was diagnosed with an intraspinal GBM metastasis. Next-generation sequencing analysis of both primary and metastatic GBM tissues was performed using the Illumina TruSight Tumor 170 assay.

Results

The number of single nucleotide variants observed in the metastatic sample was more than 2-times higher. Mutations in TP53, PTEN, and RB1 found in the primary and metastatic tissue samples are indicative of the mesenchymal GBM subtype. Among others, in the metastatic sample, there were detected two inactivating mutations (Arg1026Ile, Trp1831Ter) in the NF1 gene, two novel NOTCH3 variants of unknown significance predicted to be damaging (Pro1505Thr, Cys1099Tyr), one novel ARID1A variant of unknown significance (Arg1046Ser), and one gene fusion of unknown significance EIF2B5-KIF5B.

Conclusion

Based on the literature evidence, the inactivation of NF1, NOTCH3, and ARID1A could explain, at least in part, the acquired invasiveness and metastatic potential in this particular GBM case.

This work was supported by the grant MUNI/A/1408/2021 of the Masaryk University, Brno, Czech Republic, and INTER-EXCELLENCE Programme / INTER-COST project no. LTC20027 of the Ministry of Health, Czech Republic.
P12.11.B The role of miRNAs in glioma in response to hypoxia
Authors: Smith L C , Chakraborty D , Lourdsamy D , McIntyre D , Smith D
Published: September 2022

Background

Hypoxia, low oxygen, is a microenvironment that promotes tumour progression, particularly in gliomas. The regulation of many biological processes are maintained by miRNAs. The hypoxia status of glioma cells effects the regulation of processes by affecting the expression of individual miRNAs.The aims of this study is identifying significant miRNAs that are either under or overexpressed in hypoxia compared to normoxia in glioma cells and further exploring the effect of hypoxia on miR-92a-3p and miR-149-5p in gliomas on the apoptotic and cellular senescence pathways.

Material and Methods

A range of glioma cells were used for screening including primary cell lines: GIN28 and GIN31; low-grade cell lines: LGG19 and LGG24; paediatric cell line: SF188 and commercially available glioblastoma cell line U87. These cells were culture at both 1% (hypoxia) and 20% (normoxia) oxygen levels. Screening of miRNAs was achieved by quantitative polymerase chain reaction (qPCR) using miRNA specific primers. Knockdowns/in were achieved by transfecting with miR-92a-3p and miR-149-5p mimics and inhibitors. Caspase-glo assay was used to assess the effect of hypoxia on apoptosis.

Results

miRNA 92a-3p and miR-149-5p were found to be downregulated and upregulated respectively in primary gliomas cells in hypoxia compared to normoxia. These particular miRNAs are also found to have multiple targets in apoptosis and cellular senescence.

Conclusion

The screening of 90 miRNAs among the different categories of gliomas highlighted multiple miRNAs that were significant in hypoxia compared to normoxia. Using primary cell lines have identified hypoxia-affected miRNAs in glioblastomas. This discovery will increase our knowledge and understanding of the hypoxia effect on miRNAs which may aid and direct targeted therapy to conquer hypoxia in glioblastomas.
P12.14.A The role of onco-metabolite (R2hydroxyglutarate) in the IDH mutant glioblastoma microenvironment
Authors: Ravi V M , Behringer S , Joseph K , Beck J , Schnell O , Heiland D H
Published: September 2022

Background

Recently, we found that the reactive astrocytes in the IDH wild type glioblastoma contribute to anti-tumor immunity and support pro-oncogenic signaling. Here, we characterized the transcriptomic signature of IDH1/2-mutant glioma associated astrocytes and determined a unique inflammatory transformation, profoundly different to astrocytes in IDH wildtype glioma patients due to an onco-metabolite R-2-hydroxyglutarate using Next generation sequencing and human ex-vivo slice model.

Material and Methods

We purified and transcriptionally profiled astrocytes from 9 patients with confirmed IDH1-R132H mutation, by means of RNA-sequencing and the data were analyzed using the established pipelines. We also used spatial transcriptomics to evidently show the spatial distribution of astrocytes in IDH-mutated/wildtype glioma samples. We validated our findings using human organotypic slice model inoculated with IDH-mutant cell line or treated with oncometabolite 2-hydroxy glutarate. Additionally, LC-MS was further used to give us a chart of neurotransmitters due to altered microenvironment.

Results

Our results from RNA sequencing showed a transcriptional transformation of reactive astrocytes within the microenvironment of IDH-mutated tumors compared to wildtype glioma by means of RNA-sequencing of purified astrocytes. And, using our established human neocortical GBM model inoculated with IDH mutant tumor and R-2HG treatment, we showed that we were able to activate inflammatory transcriptional programs in astrocytes, mediated by the presence of microglia. Further, by spatially mapping the transcriptomic profiles of purified microglia, we were able to confirm that microglia also demonstrate inflammatory activation in IDH mutated glioma. This inflammatory astrocyte transformation is associated with a loss of neurotransmitter homeostasis (disrupted levels of glutamate) in the treated sections, as has been previously reported in IDH mutated tumors. Additionally, R-H2G increased neuronal spiking rate in, pointing to potential excitotoxicity.

Conclusion

Our work provides a crucial contribution towards understanding the role of R-2HG in the IDH mutant glioma microenvironment and sheds light on the significant microenvironmental differences to IDH wild-type glioma.
P13.01.A Challenges and Solutions for Establishing a CNS Tumor Registry in Africa
Authors: Fezeu F , Opara C , Djientcheu V , Fonkem E , Samnick S
Published: September 2022

Background

CNS tumor registries (CTR) has evolved to a key tool for data collection, evaluation of diagnostic and treatment of patients suffering from tumors of the central nervous system (tCNS) in the U.S, but CTR in Africa does not yet exist. In comparison to high-income countries (HIC), many low- and middle-income countries (LMIC) do not yet have national or central CNS tumor registries. Furthermore, appropriate diagnostic steps like MRI and pathological analysis are still scarce in many LMIC. Improving the availability of CTR in resource- limited regions could allow better understanding of some specificities of tCNS including incidence, prevalence, mortality and morbidity. However, CTR, MRI and pathological analysis tend to be costly and thus difficult to implement in the LMIC setting.

Material and Methods

A review of the current body of literature on tCNS in Africa was conducted using multiple scientific online data bases. Search terms included ,,CNS tumor registry,” “developing countries,” “low and middle income,” and other related terms as starting point for future initiatives.

Results

It was found that more than 1,3 billion people residing in Africa lack access to a continental CTR. There is no well established standards for reporting tCNS. Most tCNS are still underreported in many countries of Africa. The exact burden of tCNS in Africa is unknown. Although many successful, long-term, initiatives for international neurological and neurosurgical collaborations are published, any CTR of Africa similarly to the Central Brain Tumor Registry of the United States (CBTRUS) is lacking.

Conclusion:

Disparities in access to care for patients suffering from tCNS have been well published but well established solutions are still under investigations. Partnerships between centers in LMIC and HIC are making progress to better understand the burden of disease in LMIC and to create context-specific solutions for practice in the LMIC setting. Collaboration between the World Health Organisation, national centers for disease control in Africa, departments of neuroscience in LMIC and well established registries like the CBTRUS as well as other interested groups could be meaningful strategical steps to be initiated for the establishment of CTR in Africa. A CTR for Africa could lead to better comprehension of tCNS in Africa, thus facilitate prevention, diagnostic, treatment and research.
P15.01.A Metabolic-imaging of human glioblastoma explants: a new precision-medicine model to predict treatment response early
Authors: Morelli M , Lessi F , Di Stefano A , Santonocito O , Gambacciani C , Pieri F , Aquila F , Ferri G , Snuderl M , Mulholland P , Ottaviani D , Aretini P , Pasqualetti F , Franceschi S , Mazzanti C
Published: September 2022

Background

Glioblastoma (GB) is the most severe form of brain cancer, with a 12-15 month median survival. Although cell therapies for GB are on the near horizon, surgical resection, temozolomide (TMZ) and radiotherapy (RT) remain the primary therapeutic options for GB, and no new small-molecule therapies have been introduced in recent years. This therapeutic standstill is partially because preclinical models of GB do not reflect the complexities of GB cell biology. Furthermore, the aggressive progression of GB makes it critical to identify patient-tailored therapeutic strategies early.

Material and Methods

We developed a novel in-vitro 3D glioblastoma explants (GB-EXPs) model derived from patients’ resected tumors maintaining cytoarchitecture seen in the tumors. We then performed metabolic-imaging by fluorescence lifetime imaging microscopy (FLIM) on live GB-EXPs to predict drug response, using TMZ as test drug.

Results

The entire process was successfully completed within 1 week since surgery. A unique drug response sample stratification emerged that was well reflected at the molecular level, highlighting new targets associated with TMZ treatment and identifying a molecular signature associated with survival.

Conclusion

To the best of our knowledge, this is the first time that FLIM-based metabolic imaging is used on live glioblastoma explants to test anti-neoplastic drugs. FLIM-based readouts of drug response in GB explants could accelerate precision treatment of patients with GB and the identification of new anti-GB drugs.
P15.05.A Prediction of response to lomustine-based chemotherapy in glioma patients at relapse using MRI and FET PET
Authors: Wollring M M , Werner J , Bauer E K , Tscherpel C , Lohmann P , Kabbasch C , Goldbrunner R , Fink G R , Langen K J , Galldiks N
Published: September 2022

Background

This study evaluates O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET and contrast-enhanced MRI for early response assessment in glioma patients at relapse treated with lomustine-based chemotherapy.

Material and Methods

Thirty-seven adult patients with WHO CNS Grade 3 or 4 gliomas at relapse (glioblastoma, 70%; median number of relapses, 1) were retrospectively identified. Besides MRI, serial FET PET scans were performed at baseline and early after chemotherapy initiation (median number of cycles, 2). Mean and maximum tumor-to-brain ratios (TBR), metabolic tumor volumes (MTV), the occurrence of distant hotspots with a mean TBR > 1.6 at follow-up, and dynamic parameters (i.e., time-to-peak and slope) were derived from all FET PET scans. Threshold values of PET parameters were defined using receiver operating characteristic analyses to predict progression-free survival (PFS) of ≥6 months and overall survival (OS) of ≥12 months. MRI response assessment was based on RANO criteria. The predictive value of FET PET parameters and RANO criteria were subsequently evaluated using univariate and multivariate survival estimates.

Results

After treatment initiation, the median follow-up time was 11 months (range, 3-71 months). Maximum TBR and MTV (threshold, ≤0%) and RANO criteria predicted a significantly longer PFS (all P<0.001) and OS (all P<0.03). At follow-up FET PET imaging, the occurrence of new distant hotspots (n≥1) predicted a worse outcome, with significantly shorter PFS (P=0.001) and OS (P<0.001). Dynamic PET parameters did not predict a significantly longer PFS or OS (P>0.05). Multivariate survival analyses revealed that new distant hotspots at follow-up had the highest level of significance to predict non-response (P=0.002; hazard ratio, 5.722), independent of RANO criteria, IDH mutation status, and O6-methylguanine-DNA-methyltransferase promoter methylation.

Conclusion

FET PET seems to be a powerful tool for identifying responders to lomustine-based chemotherapy early after treatment initiation.
P15.08.B Intraoperative confocal laser endomicroscopy of brain tumors - potential and challenges from a neuropathological perspective
Authors: Maragkou T , Quint K , Pollo B , Hewer E
Published: September 2022

Background

Intraoperative consultation, usually in the form of a frozen section, is an integral part of current neuropathology practice. Typical indications include determination of specimen adequacy, intraoperative diagnosis and distinction between tumoral and non-tumoral tissue in diffusely infiltrating gliomas in tumor periphery. The latter is currently limited by the fact that typically not all potential regions of interest can be sampled for frozen sections and the turnaround times of frozen sections usually do not permit multiple repetitive assessments. The commercial availability of a clinical-grade in vivo laser endomicroscope for neurosurgical applications may have the potential to change this and to permit a microscopic analysis in near-real time, which in turn may have a significant impact on resection strategies for brain tumors. In this work, we investigate the potential role of CLE in neurosurgery and the transferability of histological criteria to confocal imaging.

Material and Methods

The potential role of CLE in neurosurgery in comparison to other techniques for intraoperative tumor assessment was determined by analyzing common intraoperative neuropathological workflows and identifying unaddressed opportunities. The transferability of the histological criteria from standard histology to confocal imaging was achieved by analyzing matched image pairs (standard histology and CLE) from several common tumor entities.

Results

We identified the time gap between specimen resection and the availability of the frozen section results as an important application for intraoperative CLE imaging in neurosurgery. Importantly, neuropathologists could assess tissue in near real time in an unlimited number of digital biopsies prior to resection, which adds a potent new tool to the neurosurgical armamentarium. CLE images revealed features similar to already known tissue architecture/morphology seen in standard histology, which correlated well in matched histological images. Unique aspects of individual cells and other surrounding tumor tissue elements were observed in vivo while the CLE probe acquired images throughout its focal-depth range.

Conclusion

Widespread application of CLE may have a major impact on neuropathologists' role in intraoperative diagnosis and bring along both opportunities and challenges. For broad clinical adoption, strategies for histological criteria validation as well as for determination of diagnostic accuracy need to be developed.
P15.09.A Canny edge detection algorithm for quantitative differentiation between diffuse and circumscript glioma growth patterns on MRI
Authors: Thiele F , Weller J , Katzendobler S , Trumm C , Thon N , Tonn J
Published: September 2022

Background

Lower grade gliomas show heterogenous appearance on T2-weighted MRI. Some tumors grow diffusely along axonal structures whereas others distort adjacent brain tissue through local mass effect. The diagnostic, therapeutic and prognostic implication of differential growth patterns on MRI remain unknown and are difficult to assess quantitatively.

Material and Methods

A web-based application allowing for image preprocessing and providing a comprehensive edge detection tool by means of quantifying tumor border delineation on T2-weighted images based on the canny edge detection algorithm was developed. A sigma value between 1 and 100 determined the threshold where tumor borders where not detected by the algorithm anymore, with 1 equating to the lowest threshold and thus detection of all edges contained in the image. Two experienced faculty members assigned sigma values to axial T2 images of a random sample of 20 WHO grade 2 astrocytomas, IDH-mutant and 1p/19q-non-codeleted. The sigma values were then compared with a binary, subjective rating by the same faculty staff according to the perceived predominant growth pattern (diffuse versus circumscript) of each glioma.

Results

When subjectively categorizing tumors binarily (diffuse versus circumscript), there was moderate interrater variability between observers (cohen’s kappa=0.6). Raters agreed in 16 of 20 cases, terming 7 gliomas unanimously diffuse and 9 gliomas circumscript. In 4 cases, the raters opinions diverged. The sigma values differed significantly between diffuse and circumscript tumors in both raters (rater 1, p=0.002; rater 2, p=0.018). For rater 1, the mean sigma difference between diffuse and circumscript tumors was 10.7 and 9.3 for rater 2.

Conclusion

Edge detection algorithms can be efficiently applied on MRI scans and are highly accurate in differentiating diffuse from circumscript gliomas. Objectification demands defining imaging criteria for diffuse and circumscript appearance of lower grade gliomas on MRI.
P15.10.B A multicenter phase 3 trial in progress: diagnostic performance of18F-fluciclovine PET for the detection of recurrent brain metastases after radiation therapy (REVELATE)
Authors: Chao S T , Chaglassian A , Tainer N , Teoh E J
Published: September 2022

Background

Following treatment of brain metastases, which can affect up to 40% of patients with cancer, patients will typically be closely monitored with serial brain magnetic resonance imaging (MRI) owing to the high likelihood of recurrence. The recommended follow-up modalities (CE-T1-weighted and FLAIR/T2-weighted MRI) have poor specificity, meaning that differentiation of true disease from treatment-related changes such as radiation necrosis can be difficult. Recent pilot studies have reported amino acid PET radiopharmaceutical, 18F-fluciclovine, to be potentially useful in discriminating brain tumor recurrence from treatment-related changes. This may potentially help physicians to make confident diagnoses and inform subsequent treatment plans.

Material and Methods

REVELATE (NCT04410133) will evaluate the diagnostic performance of 18F-fluciclovine PET (read with conventional MRI for anatomical reference) for the detection of recurrent brain metastases in patients for whom MRI is equivocal. This multicenter, phase 3, prospective, open-label trial aims to enroll approximately 150 subjects from across 19 US sites with solid tumor brain metastases who have undergone radiation therapy, if they have a lesion considered equivocal on MRI that requires further confirmatory diagnostic procedures (either biopsy/neurosurgical intervention or clinical follow-up). Patients will undergo 18F-fluciclovine PET <42 days after the equivocal MRI and 1-21 days pre-biopsy/neurosurgical intervention. Clinical follow-up will occur for 6m post-18F-fluciclovine PET.

Results

The primary endpoint of REVELATE is the subject-level 18F-fluciclovine negative and positive percent agreement (equivalent to specificity and sensitivity, respectively) for detection of recurrent brain metastases. Further objectives include evaluation of the lesion-level diagnostic performance, inter-reader and intra-reader agreement, and safety evaluations.

Conclusion

This ongoing phase 3 study will provide efficacy and safety data for the use of 18F-fluciclovine for the detection of recurrent brain metastases. Enrolment began in October 2020 and the trial is active but not recruiting at the time of submission.
P15.12.A Amine CEST contrast in gliomas to measure metabolic treatment effect at 7T
Authors: Abecassis Schmitz B , Ercan E , de Bresser J , Dirven L , Taphoorn M J B , van Osch M J P , Koekkoek J A F
Published: September 2022

Background

Chemical exchange saturation transfer (CEST) is an imaging technique that generates contrast based on proton exchange between water and a solute pool of interest. CEST is sensitive to molecules containing amine groups such as glutamate and creatine. Since creatine is a crucial metabolite in cellular metabolism and deregulation in cellular bioenergetics is a hallmark of cancer, CEST could be relevant for glioma imaging, specifically when evaluating treatment response. No clear consensus has been established on its use, therefore we wanted to preliminarily investigate the presence of amine CEST contrast in the contrast enhanced (CE) and non-enhanced (NE) lesions of gliomas, and to assess whether treated tumors would display different CEST contrast compared to treatment naïve tumors.

Material and Methods

We prospectively scanned 12 glioma patients on a whole-body 7 Tesla Philips Achieva MRI scanner (7 treated glioblastomas; 4 treatment naïve glioblastomas; 1 treatment naïve low-grade astrocytoma). Treatment included surgical resection, chemotherapy and radiotherapy. All patients gave informed consent. CEST images were post-processed, including corrections for B0 and B1 inhomogeneities. The CEST Z-spectra and magnetization transfer ratio (MTR) asymmetry were calculated per voxel. To retrieve the CEST values within the tumor lesions and contralateral white matter for normalization, segmentations were manually delineated on the clinical T2-FLAIR or post contrast 3D-T1.

Results

Overall we observed a relative increase of amine CEST contrast in the CE (MTRasym: Mean (x̄)=1.32; Standard deviation (σ)= 0.28) compared to a relative decrease (MTRasym: x̄=1.20; σ= 0.35) in the NE lesion. When evaluating the results from the CE and NE lesions for treated and treatment naïve groups individually, we observed a slightly different trend. In the treatment group, the CE lesions showed a higher amine CEST contrast (MTRasym: x̄=1.38; σ= 0.30) than the NE (MTRasym: x̄ = 1.11; σ = 0.302). In contrast, in the treatment naïve group, the CE lesion showed a slightly lower CEST contrast (MTRasym: x̄ = 1.23; σ=0.21) than in the NE group (MTRasym: x̄ = 1.29; σ= 0.38).

Conclusion

Our results show different amine CEST contrast trends between treated and treatment naïve groups when comparing CE and NE lesions. This suggests that treatment may have an effect on tumor tissue bioenergetics affecting the concentration of creatine. Nevertheless, future work is necessary to verify our results in a larger group of patients.