Plasma extracellular vesicles in meningioma patients following radiotherapy as liquid biopsy- a prospective explorative biomarker study (ARO 2023-05/AG-NRO-07)

BACKGROUND

While surgical resection remains the primary treatment approach for symptomatic or growing meningiomas, radiotherapy represents an auspicious alternative in patients with meningiomas not safely amenable to surgery. Biopsies are often omitted in light of potential postoperative neurological deficits, resulting in a lack of histological grading and (molecular) risk stratification. In this prospective explorative biomarker study, extracellular vesicles in the bloodstream will be investigated in patients with macroscopic meningiomas to identify a biomarker for molecular risk stratification and disease monitoring.

METHODS

In total, 60 patients with meningiomas and an indication of radiotherapy (RT) and macroscopic tumor on the planning MRI will be enrolled. Blood samples will be obtained before the start, during, and after radiotherapy, as well as during clinical follow-up every 6 months. Extracellular vesicles will be isolated from the blood samples, quantified and correlated with the clinical treatment response or progression. Further, nanopore sequencing-based DNA methylation profiles of plasma EV-DNA will be generated for methylation-based meningioma classification.

DISCUSSION

This study will explore the dynamic of plasma EVs in meningioma patients under/after radiotherapy, with the objective of identifying potential biomarkers of (early) tumor progression. DNA methylation profiling of plasma EVs in meningioma patients may enable molecular risk stratification, facilitating a molecularly-guided target volume delineation and adjusted dose prescription during RT treatment planning.

Mean global DNA methylation serves as independent prognostic marker in IDH-wildtype glioblastoma

BACKGROUND

The IDH-wildtype glioblastoma (GBM) patients have a devastating prognosis. Here, we analyzed the potential prognostic value of global DNA methylation of the tumors.

METHODS

DNA methylation of 492 primary samples and 31 relapsed samples, each treated with combination therapy, and of 148 primary samples treated with radiation alone were compared with patient survival. We determined the mean methylation values and estimated the immune cell infiltration from the methylation data. Moreover, the mean global DNA methylation of 23 GBM cell lines was profiled and correlated to their cellular radiosensitivity as measured by colony formation assay.

RESULTS

High mean DNA methylation levels correlated with improved survival, which was independent from known risk factors (MGMT promoter methylation, age, extent of resection; P = 0.009) and methylation subgroups. Notably, this correlation was also independent of immune cell infiltration, as higher number of immune cells indeed was associated with significantly better OS but lower mean methylation. Radiosensitive GBM cell lines had a significantly higher mean methylation than resistant lines (P = 0.007), and improved OS of patients treated with radiotherapy alone was also associated with higher DNA methylation (P = 0.002). Furthermore, specimens of relapsed GBM revealed a significantly lower mean DNA methylation compared to the matching primary tumor samples (P = 0.041).

CONCLUSIONS

Our results indicate that mean global DNA methylation is independently associated with outcome in glioblastoma. The data also suggest that a higher DNA methylation is associated with better radiotherapy response and less aggressive phenotype, both of which presumably contribute to the observed correlation with OS.

PerSurge (NOA-30) phase II trial of perampanel treatment around surgery in patients with progressive glioblastoma

BACKGROUND

Glioblastoma is the most frequent and a particularly malignant primary brain tumor with no efficacy-proven standard therapy for recurrence. It has recently been discovered that excitatory synapses of the AMPA-receptor subtype form between non-malignant brain neurons and tumor cells. This neuron-tumor network connectivity contributed to glioma progression and could be efficiently targeted with the EMA/FDA approved antiepileptic AMPA receptor inhibitor perampanel in preclinical studies. The PerSurge trial was designed to test the clinical potential of perampanel to reduce tumor cell network connectivity and tumor growth with an extended window-of-opportunity concept.

METHODS

PerSurge is a phase IIa clinical and translational treatment study around surgical resection of progressive or recurrent glioblastoma. In this multicenter, 2-arm parallel-group, double-blind superiority trial, patients are 1:1 randomized to either receive placebo or perampanel (n = 66 in total). It consists of a treatment and observation period of 60 days per patient, starting 30 days before a planned surgical resection, which itself is not part of the study interventions. Only patients with an expected safe waiting interval are included, and a safety MRI is performed. Tumor cell network connectivity from resected tumor tissue on single cell transcriptome level as well as AI-based assessment of tumor growth dynamics in T2/FLAIR MRI scans before resection will be analyzed as the co-primary endpoints. Secondary endpoints will include further imaging parameters such as pre- and postsurgical contrast enhanced MRI scans, postsurgical T2/FLAIR MRI scans, quality of life, cognitive testing, overall and progression-free survival as well as frequency of epileptic seizures. Further translational research will focus on additional biological aspects of neuron-tumor connectivity.

DISCUSSION

This trial is set up to assess first indications of clinical efficacy and tolerability of perampanel in recurrent glioblastoma, a repurposed drug which inhibits neuron-glioma synapses and thereby glioblastoma growth in preclinical models. If perampanel proved to be successful in the clinical setting, it would provide the first evidence that interference with neuron-cancer interactions may indeed lead to a benefit for patients, which would lay the foundation for a larger confirmatory trial in the future.

TRIAL REGISTRATION

EU-CT number: 2023-503938-52-00 30.11.2023.

Classification of Brain Tumors by Nanopore Sequencing of Cell-Free DNA from Cerebrospinal Fluid

BACKGROUND

Molecular brain tumor diagnosis is usually dependent on tissue biopsies or resections. This can pose several risks associated with anesthesia or neurosurgery, especially for lesions in the brain stem or other difficult-to-reach anatomical sites. Apart from initial diagnosis, tumor progression, recurrence, or the acquisition of novel genetic alterations can only be proven by re-biopsies.

METHODS

We employed Nanopore sequencing on cell-free DNA (cfDNA) from cerebrospinal fluid (CSF) and analyzed copy number variations (CNV) and global DNA methylation using a random forest classifier. We sequenced 129 samples with sufficient DNA. These samples came from 99 patients and encompassed 22 entities. Results were compared to clinical diagnosis and molecular analysis of tumor tissue, if available.

RESULTS

110/129 samples were technically successful, and 50 of these contained detectable circulating tumor DNA (ctDNA) by CNV or methylation profiling. ctDNA was detected in samples from patients with progressive disease but also from patients without known residual disease. CNV plots showed diagnostic and prognostic alterations, such as C19MC amplifications in embryonal tumors with multilayered rosettes or Chr.1q gains and Chr.6q losses in posterior fossa group A ependymoma, respectively. Most CNV profiles mirrored the profiles of the respective tumor tissue. DNA methylation allowed exact classification of the tumor in 22/110 cases and led to incorrect classification in 2/110 cases. Only 5/50 samples with detected ctDNA contained tumor cells detectable through microscopy.

CONCLUSIONS

Our results suggest that Nanopore sequencing data of cfDNA from CSF samples may be a promising approach for initial brain tumor diagnostics and an important tool for disease monitoring.

CTNI-07. LOMUSTINE/TEMOZOLOMIDE CHEMOTHERAPY FOR NEWLY DIAGNOSED MGMT-METHYLATED IDHWT GLIOBLASTOMA ACCORDING TO CETEG/NOA-09: REAL-WORLD EXPERIENCE IN A MULTICENTER COHORT

INTRODUCTION

The CeTeG/NOA-09 trial demonstrated superior median overall survival (mOS, 48.1 months) in MGMT-methylated glioblastoma treated with lomustine/temozolomide compared to temozolomide. We retrospectively analyzed an off-study cohort of patients treated with lomustine/temozolomide to gather real-world data on this new regimen.

METHODS

Adult patients from 20 centers in Germany, Austria and Switzerland were included. Inclusion criteria were MGMT-methylated IDHwt glioblastoma newly diagnosed prior to end of 2020, and lomustine/temozolomide treatment as part of first-line therapy.

RESULTS

321 patients with a median age of 57 years (range, 21-78) and a median follow-up of 19.9 months were included. In the whole cohort, mOS was 41.0 months (95%CI, 33.0 – not reached). In patients starting lomustine/temozolomide immediately upon initiation of radiotherapy strictly following the CeTeG protocol (88%), mOS was 52.8 months (35.8 – not reached) as compared to 24.6 months (17.6 – not reached) in patients starting lomustine/temozolomide after completion of radiotherapy/concomitant temozolomide (12%, logrank test: p = 0.06). Patients with a KPS < 80 had a shorter mOS of 19.7 months (95%CI, 16.6 – not reached) compared to 41.0 months (33.0 – not reached, p = 0.009) in KPS 80-100. Gross total resection (GTR, 53.9%) was associated with longer mOS (52.8 months, 95%CI 24.1 – not reached) compared to partial resection/biopsy (30.5 months, 95%CI 36.8 – not reached, p=0.004). Multivariable Cox regression analysis confirmed GTR (HR 0.66, p = 0.033) and younger age ( ≤ 50 years: HR 0.42, p = 0.001), but not KPS (80-100 vs. lower: HR 0.66, p = 0.12) as independent prognostic factors.

DISCUSSION

In this real-world multicenter cohort, survival was similar to the promising results of CeTeG/NOA-09. Further analyses should investigate a potentially reduced benefit from lomustine/temozolomide in patients with low KPS/no GTR and a possible detrimental effect from deferred lomustine/temozolomide initiation. The median follow-up is admittedly short, updated data will be presented.

BIOM-34. MULTIPLEX PHENOTYPING OF EXTRACELLULAR VESICLES FOR ANALYSIS OF POTENTIAL BIOMARKERS IN GLIOBLASTOMA PATIENTS

INTRODUCTION

Extracellular vesicles (EVs) carry biological information from their cell of origin that is useful for non-invasive detection of tumor biomarkers and disease monitoring. In glioblastoma (GBM), blood circulating EVs are elevated and carry GBM-associated proteins. However, it is still challenging to analyze tumor derived EVs for translational purposes. Here, we used imaging flow cytometry (IFCM) as a robust strategy to perform phenotyping of EVs with GBM related surface markers in human plasma.

METHODS

EVs were isolated via differential ultracentrifugation from plasma of (a) 40 GBM patients, pre- and post-surgery, (b) 11matched GBM relapses and (c) 12 healthy donors (HD). EV sizes and concentrations were evaluated by NTA. EV markers (CD9,CD63 and CD81) together with glioma-related markers (integrin beta-1 [ITGB1], tenascin C [TNC], Profilin-1 [PFN1], CD44,GPNMB, SPARC, HLA-II or CD133) were analyzed by IFCM. EV percentages and objects/mL plasma were compared among the groups and correlated with clinical parameters.

RESULTS

CD9 was the predominant tetraspanin in all groups (15-96%), while CD63 had the lowest levels (0-33%) and the strongestdecrease in GBM patients after surgery (fold change [FC]=-5.4, p<0.01). Among the glioma-related markers, ITGB1 and TNC displayed the most significant differences between the analyzed groups, especially the double positives ITGB1+/CD63+and TNC+/CD63+, which decreased in patients after tumor removal (FC=-3.5 and -12, respectively; p<0.001). Meanwhile,ITGB1+/CD9+and TNC+/CD9+EVs exhibited the highest levels in GBM when compared to HD subjects (FC=8.6 and 17.4;p<0.001) and upon tumor recurrence (FC=3.7 and 10.9, respectively; p<0.01).

SUMMARY/CONCLUSION

We identified EV surface antigens with potential clinical utility as GBM biomarkers. Among them, we highlight ITGB1 and TNC as the most promising markers.

PATH-33. “GENETIC AND EPIGENETIC PROFILING IDENTIFIES TWO DISTINCT CLASSES OF SPINAL MENINGIOMAS”

BACKGROUND

Spinal meningiomas account for 1.2-12 % of all meningiomas and 25-45 % of all spinal tumours. 20 % of intracranial, but only 4.6 % of spinal meningiomas recur requiring additional treatment. Whereas the classification of intracranial meningiomas has evolved considerably in recent years and uses genetic and epigenetic parameters, the classification of spinal meningiomas is based solely on histopathological findings. By embedding epi-/genetic features, the prognosis of intracranial meningiomas could be significantly improved, which is still lacking for spinal meningiomas. In our work, we integrated genetic and epigenetic parameters into the classification of spinal meningiomas.

METHODS

We performed epi-/genetic profiling of 50 spinal meningiomas. 497 intracranial meningiomas served as a reference cohort. Copy number variations (CNV) were inferred from the methylation data. Principal component (PCA) and t-SNE analysis were conducted. Clinical and histopathological parameters (location, size, recurrence, WHO°, pathological subtype) were correlated with methylation signatures using the DKFZ brain tumour classifier.

RESULTS

The methylation signature of spinal meningiomas matched to that of intracranial meningiomas (50/50), although meningioma subgroup assignment was achieved in only 13/50 cases. PCA and t-SNE analysis showed that most spinal meningiomas separate from cranial meningiomas and form two distinct clusters. Cluster 1 matched the methylation class ben-2, while cases in cluster 2 were heterogenous and had a low MSC score. Cases of cluster 1 were located in the upper spine, are more common in males and had an AKT1E17K mutation. NF2 mutations were found mainly in the second cluster, in line with a chr.22 q loss. Interestingly 4 tumors did not associate with the two spinal meningioma clusters and had a particular higher recurrence rate.

CONCLUSION

Genetic and epigenetic profiling of spinal meningiomas identifies two distinct classes of spinal meningiomas, which may allow an improved prognosis that could lead to a better guidance for adjuvant therapy.

BIOM-33. TEMPORAL HETEROGENEITY OF DNA METHYLATION SUBCLASSES BETWEEN MATCHED NEWLY DIAGNOSED AND RECURRENT IDH-WILDTYPE GLIOBLASTOMA

Spatiotemporal heterogeneity is a major factor contributing to the devastating prognosis of isocitrate-dehydrogenase (IDH)-wildtype glioblastoma. Genome-wide DNA methylation profiling allows the stratification into several DNA methylation subgroups of IDH-wildtype glioblastoma, which were shown to have a spatial heterogeneity in newly diagnosed tumors. However, the temporal heterogeneity and its clinical relevance of DNA methylation subgroups remains inconclusive. Tumor tissue obtained from first and recurrence surgery of 31 patients diagnosed with IDH-wildtype glioblastoma was subjected to DNA methylation profiling. DNA methylation profiles were analyzed for temporal heterogeneity and correlated with clinical data, survival outcome and copy number variations. In addition, deconvolution of immune cells and unsupervised hierarchical clustering using pairwise Pearson correlation coefficients of the 10.000 most variable CpG features was performed. Of all patients with matched tumor tissue, 4 (12.9%) patients had a non-matching brain tumor classifier output at recurrence. Within the remaining 27 patients, a transition of the dominant DNA methylation subclass was observed in 8 (29.6%) glioblastomas with a most frequent transition to the mesenchymal subclass (62.5%). A subclass transition was more likely after incomplete removal of contrast-enhanced tumor parts at first surgery (p = 0.04). Tumor location, adjuvant treatment, and time between primary and recurrence surgery did not influence the transition. Immune cell proportions from deconvolution data, tumor purity or specific CpG sites were not correlated with a subclass transition. Survival analyses revealed a comparable outcome for patients with or without subclass transition. Our findings demonstrate the temporal heterogeneity of DNA methylation subclasses in 29.6% of IDH-wildtype glioblastoma. We identified clinical factors and showed that a subclass transition did not impact the survival outcome. However, a possible DNA methylation subclass transition must be taken into consideration for future targeted therapies at recurrence.

QLTI-09. DEFINING GLOBAL BENCHMARK OUTCOMES FOR TRANSSPHENOIDAL SURGERY OF PITUITARY ADENOMAS: A MULTICENTER ANALYSIS OF 2862 CASES

Benchmarks are important to measure and aid in improve outcomes for surgical procedures. However, best achievable results that have been validated internationally for transsphenoidal surgery are not available. Therefore, we aimed to establish robust, standardized outcome benchmarks for transsphenoidal surgery of pituitary adenomas. A total of 2862 transsphenoidal tumor resections from 12 high-volume centers in 4 continents were analyzed. Patients were risk stratified and the median values of each center’s outcomes were established. The outcome benchmark was defined as the 75th percentile of all median values for a particular outcome as defined by Staiger et al. Out of 2862 patients, 1201 (41.9%) defined the benchmark cohort. The proportion of benchmark cases contributing to the final cohort ranged across centers between 22.1% to 59.7%. Within the benchmark cases, 928 (73.3%) patients underwent microscopic (MTS) and 263 (21.9%) patients endoscopic endonasal resection (EES). The overall postoperative complication rate was 18.9% with an in-hospital mortality between 0.0-0.8%. Benchmark cutoffs were ≤ 3.3% for reoperation rate, ≤ 4.6% for cerebrospinal fluid leak requiring intervention, and ≤ 15.3% for transient diabetes insipidus. At 6 months follow-up, benchmark cutoffs were calculated as follows: readmission rate: ≤ 7.1%, new hypopituitarism ≤ 15.5%, new neurological deficit ≤ 1.2%, tumor remnant ≤ 25.5%. This analysis defines benchmark values for transsphenoidal resection of pituitary adenomas targeting morbidity, mortality, surgical and tumor-related outcomes. The benchmark cutoffs can be used to assess different centers, patients’ populations, and novel surgical techniques.

BIOM-10. CIRCULATING EXTRACELLULAR VESICLES AS A TOOL FOR DIAGNOSIS, PROGNOSIS AND MONITORING IN GLIOMA

OBJECTIVE

Extracellular vesicles (EVs) represent a population of lipid bilayer nanoparticles released by all cell types, including tumor cells that can serve as a noninvasive source for liquid biopsy. To date, MRI images have been the established method for monitoring treatment efficacy in brain tumor patients. We investigated the potential of pure EV count for diagnosis, prognosis, and treatment monitoring in gliomas.

METHODS

Plasma samples, differential blood counts, at multiple timepoints before and after surgery of glioblastoma patients (n=101) were collected. Follow-up samples were obtained every 3 months. Healthy donors served as controls (n=29). Plasma EVs concentration was measured by Nanoparticle Tracking Analysis (NTA). EVs were characterized by electron microscopy and imaging flow cytometry. Tumor burden was measured by MRI images. Clinical characteristics were prospectively recorderd. In addition plasma EVs from Mut3 tumor bearing mice were analysed at d3, d5, d7, d10, d12 after tumor injection (n=20). MRI images and differential blood counts were analyzed.

RESULTS

Glioblatoma patients have a 5-fold increase of plasma EVs compared to HD; p < 0.0001). Circulating EVs counts correlated only with FLAIR hyperintensity and with no other MRI or blood-based parameter. Similar results were obtained from Mut3 tumor mice. Dichotomisation of GBM patients in EVhigh and low revealed a significant overall survival and progression free survival benefit for EVlow patients (p=0.004). After surgery, EVs decreased significantly (5-fold, p< 0.0001). A massive drop in EVs was associated with gross-total resection (p < 0.05). At the time of tumor recurrence, the number of circulating EVs increased in all patients during a follow-up (9 months).

CONCLUSION

Our findings highlight the potential of circulating EVs as a biomarker tool for diagnosis, prognosis and treatment monitoring in GBM patietns, as they seem to reflect the presence of a tumor mass and thus may assist in clinical decision making.

TMIC-64. EXTRACELLULAR VESICLE TRAFFICKING IN GBM

Extracellular vesicles (EVs) are secreted by all cell types, including tumor cells, and are found in increased numbers in the plasma of GBM patients. EVs may contain high-value genetic material that can be useful for tracking tumor development, as well as membrane proteins that affect other cells. This prompted us to investigate how tumor EVs might influence immune cells in glioma, and in primary and secondary lymphoid organs as well as in the circulation. To this end we used a syngeneic GBM mouse model and tracked tumor EVs from the brain to the meninges, cervical lymph nodes, plasma, bone marrow and spleen. Interestingly, we were able to identify tumor EVs mostly in the cervical lymph nodes by ImageStream imaging flow cytometry just 30min after tumor EV injection into the brain. However, when tumor EVs were produced by a large gliomas transfected with dTomato, we found them mainly in plasma, less frequently in bone marrow and never in the spleen. We confirmed these data by extracting DNA from EVs and detecting specific dTomato sequences using digital droplet PCR. In addition, we detected CD11b+ macrophages in the meninges that likely travel through the lymphatics that have taken up tumor EV or tumor material. We confirm that tumor EVs are capable of eliciting an immune response by activating T cells. However, prolonged contact and large number of EVs could also block antigen recognition by T cells and thus contribute to the propagation of an immunosuppressive environment in GBM.

BIOM-32. DNA METHYLATION SUBCLASSES PREDICT THE BENEFIT FROM GROSS TOTAL TUMOR RESECTION IN IDH-WILDTYPE GLIOBLASTOMA PATIENTS

DNA methylation-based tumor classification allows an enhanced distinction into subgroups of glioblastoma. However, the clinical benefit of DNA methylation-based stratification of glioblastomas remains inconclusive. We performed a multicentric cohort study including 430 patients with newly diagnosed glioblastoma whose tumors were subjected to DNA methylation profiling. The primary outcome was overall survival (OS) and progression-free survival (PFS). Secondary outcomes were the prognostic relevance of EOR and MGMTpromoter methylation status as well as surgical benefit for recurrent glioblastoma. After stratifying patients in accordance with their DNA methylation subclasses RTK I, RTK II, and mesenchymal (MES), outcome analyses revealed no significant differences between these three methylation subclasses (p = 0.06). RTK I or RTK II tumors who underwent gross-total resection (GTR) or near GTR had a longer OS and PFS than partially resected patients (p < 0.01). In the MES subclass, no survival benefit for a maximized EOR was found (p = 0.33). In multivariate analysis, the therapy response-predictive value of MGMT promoter methylation was evident for RTK I (p < 0.01) and RTK II (p = 0.02) but failed to be an independent factor in the MES subclass (p= 0.06). For local recurrence, re-resection conveyed a progression-to-overall survival (POS) benefit (p < 0.01), which was evident in the RTK I (p = 0.03) and RTK II (p < 0.01) subclasses, but not in the MES subclass (p = 0.33).This study demonstrates a survival benefit from maximized EOR at surgery for newly diagnosed and recurrent glioblastomas of the RTK I and RTK II subclass but not the MES subclass. Hence, it needs to be carefully considered whether the MES subclass should be treated with maximal surgical resection, especially when located in eloquent areas and at time of recurrence.

BIOM-52. DIAGNOSTIC POTENTIAL OF EXTRACELLULAR VESICLES IN MENINGIOMA PATIENTS

Standard monitoring after meningioma resection relies on serial MRI examinations, which are time-consuming, expensive and provide no information on molecular alterations that may indicate progression towards a more aggressive tumor. Extracellular vesicles (EVs) secreted by tumor cells play an important role in cell-cell communication, and tumor-derived EVs circulating in patient blood can serve as biomarkers. We investigated the potential role of plasma EVs in meningioma patients for tumor detection and determined whether EVs secreted by meningioma cells reflect epigenetic, genomic and proteomic alterations of original tumors. EV concentrations were quantified in patient plasma (n = 46). Short-term meningioma cultures were established (n = 26) and secreted EVs were isolated. Methylation and copy number profiling was performed using 850k arrays, and mutations were identified by targeted gene panel sequencing. Differential quantitative mass spectrometry was employed for proteomic analysis. We found that the levels of circulating EVs were significantly elevated in meningioma patients compared to healthy individuals, and that plasma EV concentrations correlated with malignancy grade and extent of peritumoral edema. Postoperatively, EV counts dropped to normal levels, and the magnitude of the postoperative decrease was associated with extent of tumor resection (Simpson grade). Methylation profiling of EV-DNA allowed correct tumor classification as meningioma in all investigated cases, and accurate methylation subclass assignment in nearly all cases. Copy number variations present in tumors, as well as tumor-specific mutations were faithfully reflected in meningioma EV-DNA. Proteomic EV profiling did not permit original tumor identification but revealed tumor-associated proteins such as desmoplakin that could potentially be utilized to enrich meningioma EVs from biofluids. In conclusion, elevated EV levels in meningioma patient plasma may aid in tumor diagnosis and assessment of treatment response. Meningioma EV-DNA mirrors genetic and epigenetic tumor alterations and facilitates molecular tumor classification.

TBIO-07. Pediatric tumor classification through genome-wide methylation profiling of extracellular vesicle DNA

BACKGROUND: Genome-wide methylation profiling reliably classifies pediatric central nervous system (CNS) tumors. Extracellular vesicles (EVs) are released by pediatric CNS tumor cells (pCC) and contain high molecular weight tumor DNA, rendering EVs a potential biomarker source to identify tumor subgroups, stratify patients and monitor therapy by liquid biopsy. We investigated, whether the DNA in pCC-derived EVs reflects genome-wide tumor methylation profiles and allows tumor subtype classification. Currently, the tests are being expanded to include blood samples (n=80 patients). METHODS: DNA was isolated from EVs secreted by pediatric CNS tumor cells (pCC) as well as from the shortly cultured tumor cells and from the original tumor samples (n=4 patients). Pediatric Fibroblasts and EVs derived thereof were used as a non-tumorous control. EVs were classified by nanoparticle analysis (NTA), immunoblotting, imaging flow cytometry (IFCM and electron microscopy. Genome-wide DNA methylation profiling was performed using an 850k Illumina EPIC array and results were classified according to the DKFZ brain tumor classifier and further analysed by t-SNE and Copy number alteration analysis (CNA). RESULTS: The size range of pCC-derived EVs was 120-150 nm, as measured by NTA. The majority of secreted EVs exhibited high expression of common EV markers (i.e. CD9, CD63 and CD81), as characterized by IFCM. Genome-wide DNA methylation profiling of pCC-derived EVs correctly identified the methylation class of the original tumor (i.e. pilocytic astrocytoma, medulloblastoma). In addition, t-SNE analysis and copy number alterations matched the pattern of the parental pCC and original tumor samples. CONCLUSION: EV DNA faithfully reflects the tumor methylation class and copy number alterations present in the parental cells and the original tumor. Methylation profiling of circulating tumor EV DNA could become a useful tool to detect and classify pediatric CNS tumors.

SURG-14. Value of the Classification of Intraoperative Adverse Events (ClassIntra) for Resection of CNS Neoplasms in Pediatric and Adolescent Patients

OBJECTIVE: Outcome measuring is increasingly important in neurosurgery. Recently, a classification for assessing Intraoperative adverse events (iAE) was introduced (ClassIntra). We aimed to analyze the reliability of the ClassIntra to reflect Intraoperative complications and the potential to predict the outcome of pediatric and adolescent patients who underwent resection of CNS neoplasms. METHODS: A prospective study between 01 July and 31 December 2021 was conducted. The ClassIntra grade for each tumor resection was evaluated at sign-out (Grade 0 to V). Postoperative complications were graded after Clavien-Dindo and Comprehensive Complication Index (CCI). Neurological status was assessed prior surgery and at discharge using Lansky Index, NIHSS, NANO, GCS, and mRS. RESULTS: 21 pediatric and adolescent patients who underwent resection of CNS neoplasms were included. Of these, 8 (38.1%) were female with a mean (SD) age of 9.9 (5.2) years. During 13 (61.9%) resection an iAE was noted, of which 11 (52.4%) were classified as ClassIntra I and 2 (9.5%) as ClassIntra II. The majority (66.7%) underwent surgery for infratentorial pathology, whereas 4 (19.0%) had a supratentorial and 3 (14.3%) a spinal pathology. Preoperative characteristics did not correlate with the severity of ClassIntra. In patients without an iAE, a gross total resection was achieved more frequently (p=0.048). Focusing on postoperative outcome revealed a higher severity of cumulative complications as presented by the CCI (10.4 versus 40.5), longer hospital stay (p=0.04), and higher 30-day readmission rate (p<0.01) in patients with an iAE. However, the neurological outcome and time to begin of adjuvant treatment did not correlate with the ClassIntra. CONCLUSION: Findings of this study suggest that the ClassIntra is sensitive for assessing iAEs and sufficient to identify cases with a higher risk for developing postoperative complications after resection of CNS neoplasms in pediatric and adolescent patients, but cannot predict a possible neurological deterioration.

The blood-brain barrier is dysregulated in COVID-19 and serves as a CNS entry route for SARS-CoV-2

Neurological complications are common in COVID-19. Although SARS-CoV-2 has been detected in patients’ brain tissues, its entry routes and resulting consequences are not well understood. Here, we show a pronounced upregulation of interferon signaling pathways of the neurovascular unit in fatal COVID-19. By investigating the susceptibility of human induced pluripotent stem cell (hiPSC)-derived brain capillary endothelial-like cells (BCECs) to SARS-CoV-2 infection, we found that BCECs were infected and recapitulated transcriptional changes detected in vivo. While BCECs were not compromised in their paracellular tightness, we found SARS-CoV-2 in the basolateral compartment in transwell assays after apical infection, suggesting active replication and transcellular transport of virus across the blood-brain barrier (BBB) in vitro. Moreover, entry of SARS-CoV-2 into BCECs could be reduced by anti-spike-, anti-angiotensin-converting enzyme 2 (ACE2)-, and anti-neuropilin-1 (NRP1)-specific antibodies or the transmembrane protease serine subtype 2 (TMPRSS2) inhibitor nafamostat. Together, our data provide strong support for SARS-CoV-2 brain entry across the BBB resulting in increased interferon signaling.

•

IFNγ signaling is upregulated in COVID-19 human neurovascular unit

•

SARS-CoV-2-infected hiPS-BCECs display similar upregulation of IFNγ signaling

•

SARS-CoV-2 replicates in hiPS-BCECs and is released while barrier remains intact

•

SARS-CoV-2 infection of hiPS-BCECs is decreased by antibodies and protease inhibitors

Integrated Molecular-Morphologic Meningioma Classification: A Multicenter Retrospective Analysis, Retrospectively and Prospectively Validated

PURPOSE

Meningiomas are the most frequent primary intracranial tumors. Patient outcome varies widely from benign to highly aggressive, ultimately fatal courses. Reliable identification of risk of progression for individual patients is of pivotal importance. However, only biomarkers for highly aggressive tumors are established (CDKN2A/B and TERT), whereas no molecularly based stratification exists for the broad spectrum of patients with low- and intermediate-risk meningioma.

METHODS

DNA methylation data and copy-number information were generated for 3,031 meningiomas (2,868 patients), and mutation data for 858 samples. DNA methylation subgroups, copy-number variations (CNVs), mutations, and WHO grading were analyzed. Prediction power for outcome was assessed in a retrospective cohort of 514 patients, validated on a retrospective cohort of 184, and on a prospective cohort of 287 multicenter cases.

RESULTS

Both CNV- and methylation family-based subgrouping independently resulted in increased prediction accuracy of risk of recurrence compared with the WHO classification (c-indexes WHO 2016, CNV, and methylation family 0.699, 0.706, and 0.721, respectively). Merging all risk stratification approaches into an integrated molecular-morphologic score resulted in further substantial increase in accuracy (c-index 0.744). This integrated score consistently provided superior accuracy in all three cohorts, significantly outperforming WHO grading (c-index difference P = .005). Besides the overall stratification advantage, the integrated score separates more precisely for risk of progression at the diagnostically challenging interface of WHO grade 1 and grade 2 tumors (hazard ratio 4.34 [2.48-7.57] and 3.34 [1.28-8.72] retrospective and prospective validation cohorts, respectively).

CONCLUSION

Merging these layers of histologic and molecular data into an integrated, three-tiered score significantly improves the precision in meningioma stratification. Implementation into diagnostic routine informs clinical decision making for patients with meningioma on the basis of robust outcome prediction.

BIOM-39. METHYLATION AND MUTATION PROFILES IN MENINGIOMA CELL-DERIVED EXTRACELLULAR VESICLE DNA REFLECT EPIGENETIC AND GENOMIC ALTERATIONS IN ORIGINAL TUMORS

The majority of meningiomas are benign but approximately 20% of display an aggressive behavior, resulting in significant patient morbidity and mortality. Standard monitoring after meningioma resection relies on serial MRI examinations, which are time-consuming, expensive and provide no information on molecular alterations that may indicate progression towards a more aggressive tumor. Extracellular vesicles (EVs) are released by tumor cells and contain high molecular weight DNA, rendering circulating EVs a potential biomarker source for non-invasive disease monitoring and for obtaining information on genetic and epigenetic alterations. We quantified EVs in plasma of 46 meningioma patients (n = 29 M1, 12 M2, 5 M3) by nanoparticle tracking analysis and detected significantly higher levels compared to age-matched healthy donors (n = 18). EV concentrations correlated with malignancy grade (p = 0.0049) and with the extent of peritumoral edema (p = 0.0031). Comparisons between paired pre- and postoperative samples revealed that EV levels counts dropped significantly the day after tumor resection and were reduced to normal levels after about one week. Completely resected patients (Simpson grade I) displayed a greater reduction of postoperative EV concentrations than incompletely resected patients. DNA methylation profiling was performed on EVs secreted by cultured meningioma cells, as well as matched cells and original tumors using 850k arrays (n = 7 M1, 5 M2, 3 M3). All EV samples were correctly identified as meningiomas by the Heidelberg classifier, and methylation subclasses were also correctly assigned in almost all cases. t-SNE analysis showed that EVs mapped in close proximity to their corresponding parental cells and tumor tissue. Tumor specific mutations and copy number variations were detected in EV-DNA with high accuracy. Differential quantitative proteomic analysis of EVs, cells and tumors identified shared proteins that could potentially be useful for enriching tumor-derived circulating EVs from biofluids.

BIOM-19. DECIPHERING THE METHYLATION SIGNATURE OF CIRCULATING EXTRACELLULAR VESICLE DNA FOR CNS TUMOR CLASSIFICATION

Genome-wide methylation profiling has recently been developed into a tool that allows subtype tumor classification in central nervous system (CNS) tumors. We previously showed that extracellular vesicle (EV) DNA faithfully reflects the tumor methylation class, including information on the IDH mutation and MGMT promoter methylation status. Furthermore we showed that circulating plasma EVs are elevated in CNS tumor patients in comparison to non-tumor donors (HD) controls with tumor related protein profiles. We now investigated, whether the methylation signatures of circulating DNA (both EV and cfNDA) can be used in liquid biopsy approaches for CNS tumor detection and classification. We isolated DNA from circulating EVs (n=27), cfDNA (n=27) and tumor tissue DNA (n=90) of patients with glioblastoma (GBM), meningioma (MGN) and cerebral metastases (CM). Patients undergoing epilepsy surgery as well as aneurysm clipping were used as non-tumor controls (HD, n= 7). EVs were classified by nanoparticle analysis, immunoblotting, imaging flow cytometry and electron microscopy. Isolated EV-DNA comprised many sorts of molecular weight (up tp >10Kb) in comparison to cfDNA (130-140bp). Healthy donors and tumor patients showed not differences in their DNA size profiles. We performed genome-wide methylation profiling by 850k Illumina EPIC arrays for all DNA analytes and tumor entities. Linear models and empirical Bayes methods identified significant differentially methylated CpGs (GBM vs. HD, MGN, vs HD, CM vs. HD), that revealed tumor specific signatures to detect and discriminate different CNS tumor entities. Visualization of differentially methylated CPGs by dimension reduction (PCA, t-SNE, Umap) verified tumor specific clusters. cfDNA and EV-DNA exhibited distinctive individual CpG profiles. Our study shows that the methylation signature of circulating EV DNA and cfDNA can be used to separate healthy individuals from tumor patients and could potentially complement standard-of-care imaging to improve tumor detection, classification and surveillance.

PATH-39. INTEGRATED MOLECULAR-MORPHOLOGICAL MENINGIOMA CLASSIFICATION: A MULTICENTER RETROSPECTIVE ANALYSIS, RETRO- AND PROSPECTIVELY VALIDATED

PURPOSE

Meningiomas are the most frequent primary intracranial tumors. Patient outcome varies widely from cases with benign to highly aggressive, ultimately fatal courses. Reliable identification of risk of progression for the individual patient is of pivotal importance in clinical management. However, only biomarkers for highly aggressive tumors are established at present (CDKN2A/B and TERT), while no molecularly-based stratification exists for the broad spectrum of low- and intermediate-risk meningioma patients.

PATIENTS AND METHODS

DNA methylation data and copy-number information were generated for 3,031 meningiomas of 2,868 individual patients, with mutation data for 858 samples. DNA methylation subgroups, copy-number variations (CNV), mutations and WHO grading were comparatively analyzed. Prediction power for outcome of these parameters was assessed in an initial retrospective cohort of 514 patients, and validated on a retrospective cohort of 184, and on a prospective cohort of 287 multi-center cases, respectively.

RESULTS

Both CNV and methylation family- (MF)-based subgrouping independently resulted in an increase in prediction accuracy of risk of recurrence compared to the WHO classification (c-indexes WHO 2016, CNV, and MF 0.699, 0.706 and 0.721, respectively). Merging all independently powerful risk stratification approaches into an integrated molecular-morphological score resulted in a further, substantial increase in accuracy (c-index 0.744). This integrated score consistently provided superior accuracy in all three cohorts, significantly outperforming WHO grading (c-index difference p=0.005). Besides the overall stratification advantage, the integrated score separates more precisely for risk of progression at the diagnostically challenging interface of WHO grade 1 and grade 2 tumors (HR 4.56 [2.97;7.00], 4.34 [2.48;7.57] and 3.34 [1.28; 8.72] for discovery, retrospective, and prospective validation cohort, respectively).

CONCLUSIONS

Merging these layers of histological and molecular data into an integrated, three-tiered score significantly improves the precision in meningioma stratification. Implementation into diagnostic routine informs clinical decision-making for meningioma patients on the basis of robust outcome prediction.

TAMI-39. INTEGRATION OF SPATIALLY RESOLVED TRANSCRIPTOMICS AND METABOLOMICS UNCOVERS HYPOXIA-DRIVEN ACCUMULATION OF GENOMIC INSTABILITIES IN HUMAN GLIOMA

High-dimensional technologies have provided insights into transcriptional heterogeneity and dynamic plasticity which are hallmarks of brain tumors. Although scRNA-seq recovers the diversity of transcriptional states, their spatial context within the neuronal environment has remained unexplored. Here, we integrated spatially resolved transcriptomics and metabolomics to characterize the glioma landscape at multiple molecular levels. We integrated spatial transcriptomics (10X Visium, n= 28) and metabolomics (MALDI, n= 6) from primary and recurrent glioblastoma patients. Unsupervised cluster analysis and pattern recognition uncovered 5 spatially distinct transcriptional programs, shared across patients. These included three cell-specific developmental stages largely reflecting those that are part of recently suggested models. By integrating metabolome data, we identified an additional program encompassing reactive responses to hypoxia. Areas of hypoxic response were negatively correlated with proliferation (R2= -0.34, p< 0.001) and significantly enriched for gene expression signatures from the S-phase (p< 0.001). Modeling of transient spatial gradients using vector field predictions showed opposing vector directions of hypoxia response and migratory capacity, underpinning the “go-or-growth” theory, where cells either proliferate or migrate. Inferred copy-number alterations (CNA) revealed a significant increase in genomic instability, highly correlated to hypoxia response (R2= 0.78, p< 0.001). Near necrotic areas, we observed a significant accumulation of CNAs while proliferation was inhibited, and cells remained in the S-phase. We validated this hypothesis of hypoxia-driven accumulation of CNAs by chronic hypoxia cultures of primary patient-derived cell lines. A gain of chromosomal instability after long-term hypoxia was observed, suggesting that hypoxic areas in glioblastoma function as bioreactors for genomic instability. Our findings elucidate the evolution of resistant subclones in glioblastoma. They provide novel insights into the dynamic regulation and interaction between host and tumor and cast a new light on hypoxic and necrotic areas, which may represent the source of the heterogeneous and resistant nature of glioblastomas.

BIOM-09. MULTIPLEX ANALYSIS OF CSF EXTRACELLULAR VESICLES OF INTRASPINAL TUMORS

BACKGROUND: Extracellular vesicles (EVs) play an important role in cell-cell communication in different types of tumors, carrying multiple layers of biological functional molecules, including proteins, RNA, DNA and lipids. We previously demonstrated that extracellular vesicles (EV) from central nervous system tumors reflect the molecular subtype of the original tumor and mediate an exchange of pro-oncogenic signals. Their implication as biomarkers in tumor disease is under current investigation. It is unclear, however, to what extent cerebrospinal fluid (CSF) EVs from intraspinal tumors are utilizable for diagnostical purposes and how their marker profiles overlap with EVs derived from non tumorous EVs. We analyzed CSF EVs of intraspinal tumors to define CSF EV profiles that allow tumor subtype classification. METHODS: EVs were isolated from CSF of patients suffering from intraspinal meningioma (n=5), ependymoma (n=7) and neurinoma (n=5). Patients suffering from normal pressure hydrocephalus were used as controls (n=5). EVs were analyzed by multiplex bead based assay, immunoblotting, electron microscopy and NTA. RESULTS: CSF EVs were 97.21 ± 3.37nm (intraspinal tumor patients) and 101.6 ± 3.68nm (controls) in sizes and showed vesicular structures by electron microscopy. Particle number were not significantly different between both groups (p = 0.103). Using our 37 protein mutliplex EV profiling kit we found 29 proteins to be expressed in a sufficient manner on CSF EVs. CSF EVs of intraspinal meningioma showed elevated CD62P, HLA-DR, CD40, CD42a and CD45 expression levels, while ependymoma showed decreased levels of CD9, CD63, CD81, whereas neurinomas had elevated levels of SSEA-3 and CD25. CONCLUSION: This is the first comprehensive analysis of CSF EV of intraspinal tumor patients. CSF EV display distinct subpopulations that may allow tumor classification and long-term surveillance. However as tumor-specific EVs may be rare, there is still the need to identify markers that can enrich tumor-specific EVs for molecular profiling.

BIOM-57. PEDIATRIC TUMOR CLASSIFICATION THROUGH GENOME-WIDE METHYLATION PROFILING OF EXTRACELLULAR VESICLE DNA

BACKGROUND

Genome-wide methylation profiling reliably classifies pediatric central nervous system (CNS) tumors. Extracellular vesicles (EVs) are released by pediatric CNS tumor cells (pCC) and contain high molecular weight tumor DNA, rendering EVs a potential biomarker source to identify tumor subgroups, stratify patients and monitor therapy by liquid biopsy. We investigated whether the DNA in pCC-derived EVs reflects genome-wide tumor methylation profiles and allows tumor subtype classification.

METHODS

DNA was isolated from EVs secreted by pediatric CNS tumor cells (pCC) as well as from the shortly cultured tumor cells and from the original tumor samples (n=4 patients). Pediatric Fibroblasts and EVs derived thereof were used as a non-tumorous control. EVs were classified by nanoparticle analysis (NTA), immunoblotting, imaging flow cytometry (IFCM and electron microscopy. Genome-wide DNA methylation profiling was performed using an 850k Illumina EPIC array and results were classified according to the DKFZ brain tumor classifier and further analysed by t-SNE and Copy number alteration analysis (CNA).

RESULTS

The size range of pCC-derived EVs was 120–150 nm, as measured by NTA. The majority of secreted EVs exhibited high expression of common EV markers (i.e. CD9, CD63 and CD81), as characterized by IFCM. Genome-wide DNA methylation profiling of pCC-derived EVs correctly identified the methylation class of the original tumor (i.e. pilocytic astrocytoma, medulloblastoma). In addition, t-SNE analysis and copy number alterations matched the pattern of the parental pCC and original tumor samples.

CONCLUSION

EV DNA faithfully reflects the tumor methylation class and copy number alterations present in the parental cells and the original tumor. Methylation profiling of circulating tumor EV DNA could become a useful tool to detect and classify pediatric CNS tumors.

CSIG-11. CENTRAL NERVOUS SYSTEM TUMOR PATIENTS HAVE ELEVATED LEVELS OF CIRCULATING EXTRACELLULAR VESICLES

BACKGROUND

We previously demonstrated that extracellular vesicles (EV) from CNS tumors reflect the molecular subtype of the original tumor and mediate an exchange of pro-oncogenic signals. EVs are commonly characterized by nanoparticle analysis (NTA), electron microscopy and tetraspanin markers, including CD9, CD81 and CD63. It is unclear, however, to what extent circulating tumor EVs are utilizable for diagnostic purposes and how their marker profile overlaps with EVs derived from other cell types. Aiming to define markers that allow distinction and enrichment of glioma EVs from patient blood, we utilized Imaging Flow Cytometry (IFC) to discriminate single EVs via multiple surface markers.

METHODS

EVs were isolated from blood of patients suffering from glioblastoma (n=24), anaplastic astrocytoma (n=8), brain metastasis (n=7), meningioma (n=12), pituitary gland tumor (n=11), epilepsy (n=11) and from healthy controls (n=18) and were analyzed by IFC, immunoblotting, electron microscopy and NTA. In addition, circulating EVs from PALM-GFP-GL261 and PALM-GFP-CT2A tumor-bearing mice (n=5) as well as from glioblastoma stem-like (GSC) cultures (n=4), neural stem cells (NSC), cerebral endothelial cells (cEC) and T-cells (n=4) were characterized.

RESULTS

CNS tumor patients have significantly elevated levels of circulating EVs (P < 0.001), as measured by NTA and IFC. In particular, the proportion of double positive CD9+/CD81+, CD9+/CD63+and CD63+/CD81+EVs is increased in glioblastoma patients (p=0.018) compared with healthy controls[L1]. In accordance, cultured GSCs secrete increased levels of CD9+/CD81+EVs in vitro. In the two syngeneic murine PALM-GFP glioma models, only 0.1-0.01% of circulating plasma EVs were found to be derived from intracranial tumors, underlining the need to identify markers that can enrich tumor-specific EVs for molecular profiling.

CONCLUSION

Glioma patients display increased levels of circulating plasma EVs that can be profiled by IFC, which is a unique and novel technique that facilitates discrimination of different EV subpopulations.

CSIG-09. PROTEOMIC ANALYSIS OF MENINGIOMA CELL-DERIVED EXTRACELLULAR VESICLES: FIRST OF A KIND

BACKGROUND

Extracellular vesicles (EVs) play an important role in cell-cell communication in different types of tumors, carrying multiple layers of biological functional molecules, including proteins, RNA, DNA and lipids. Their implication as biomarkers in tumor disease is under current investigation. We previously showed that EVs in glioblastoma reflect the tumor subtype and that glioblastoma patients have elevated circulating particle counts. Regarding to meningioma, it is not known to what extent these usually benign tumors secrete EVs and how these EVs reflect the tumor. Here we report the first study that analyzed meningioma cell-derived EVs.

METHODS

Meningioma tissue, short-term cell cultures and cell culture-derived EVs (menEVs), (n=4) were analyzed by global mass-spectromety, immunoblotting and imaging flow cytometry and compared to EVs from glioblastoma short-term cell cultures (gEVs), (n=4). Plasma EVs from meningioma patients (n = 12) were analyzed for their tetraspanin marker expression (CD9, CD81 and CD63). EVs were further analyzed by nanoparticle analysis (NTA) and electron microscopy.

RESULTS

menEVs were 110-140nm in size and exhibited vesicular structures by electron microscopy. We identified 269 proteins in menEVs through mass spectometry. 45 proteins were upregulated in menEVs compared to short-term cell culture and original tumor tissue. 99 proteins were exclusively found in menEVs compared to gEVs, with osteopontin being the top highly expressed protein within the mEV fraction. Both meningioma and glioblastoma patients have elevated circulating plasma EV counts (p< 0.01), as measured by NTA.

CONCLUSION

The increase in circulating plasma EVs in meningioma patients suggests that tumor cell-derived EVs augment the pool of circulating EVs and could be utilized to obtain information on the tumor by liquid biopsy. Osteopontin is known to be expressed at high levels in meningiomas and its association with menEVs may facilitate isolation of circulating meningioma-specific EVs for analysis.

GENE-22. GENOME-WIDE METHYLATION PROFILING OF GLIOBLASTOMA EXTRACELLULAR VESICLE DNA ALLOWS TUMOR CLASSIFICATION

BACKGROUND

Genome-wide methylation profiling has recently been developed into a tool that allows subtype tumor classification in central nervous system (CNS) tumors. Extracellular vesicles (EVs) are released by CNS tumor cells and contain high molecular weight tumor DNA, rendering EVs a potential biomarker source to identify tumor subgroups, stratify patients and monitor therapy by liquid biopsy. We investigated whether the DNA in glioma-derived EVs reflects genome-wide tumor methylation profiles and allows tumor subtype classification.

METHODS

DNA was isolated from EVs secreted by cultured glioma stem-like cells (GSC) as well as from the cells of origin and from the original tumor samples (n=3 patients). EVs were classified by nanoparticle analysis (NTA), immunoblotting, imaging flow cytometry (IFCM), multiplex EV assays and electron microscopy. Genome-wide DNA methylation profiling was performed using an 850k Illumina EPIC array and results were classified according to the DKFZ brain tumor classifier.

RESULTS

The size range of GSC-derived EVs was 120–150 nm, as measured by NTA. The majority of secreted EVs exhibited high expression of common EV markers (i.e. CD9, CD63 and CD81), as characterized by IFCM and multiplex EV assays. Genome-wide methylation profiling of GSC-derived EVs correctly identified the methylation class of the original tumor, including information on the IDH mutation status and subclass classification (RTK1, RTK2). In addition, copy number alterations and the MGMT metyhlation status matched the pattern of the parental GSCs and original tumor samples.

CONCLUSION

EV DNA faithfully reflects the tumor methylation class as well as the MGMT methylation status and copy number variations present in the parental cells and the original tumor. Methylation profiling of circulating tumor EV DNA could become a useful tool to detect and classify CNS tumors.

MNGI-02. FEATURES OF TUMOR TEXTURE INFLUENCE SURGERY AND OUTCOME IN INTRACRANIAL MENINGIOMA

OBJECTIVE

Texture-related factors such as consistency, vascularity and adherence vary considerably in meningioma and are thought to be linked with surgical resectability and morbidity. However, data analyzing the true impact of meningioma texture on the surgical management is sparse.

METHODS

Patients with intracranial meningioma treated between 08/2014-04/2018 were prospectively collected for demographics and surgical treatment with related morbidity and extend of resection (EOR). Tumor characteristics were reported by the surgeon using a standardized questionnaire including items such as tumor rigidity, homogeneity, vascularization and adherence to surrounding neurovascular structure and analyzed for their impact on EOR and neurological outcome using multivariate regression analyses.

RESULTS

296 patients (214 female (72.3%) with intracranial meningiomas were included with a mean age of 60.4 years. 23% of patients had a transient and 6.1% permanent neurological deficits and three patients (1.1%) died. The occurrence of a neurological deficit was associated with duration of surgery (p = 0.013) and tumor adherence to neurovascular structures (p = 0.014). Similar associations were observed in subgroup analyses of different tumor localizations (e.g. convexity and skull base). With regard to EOR, the tumor adherence (p < 0.001) and recurrent surgery (p = 0.001) were found as independent predictors for subtotal resection. Noteworthy, the tumor rigidity had no significant impact on the morbidity or EOR.

CONCLUSION

Our analysis supports the notion that tumor texture has an impact on the surgical management of meningioma and provides sound data that tumor adherence is a significant factor influencing neurological outcome and EOR. In contrast, the influence of tumor rigidity has less impact than previously thought. Preoperative prediction of tumor texture is therefore required for optimized risk assessment.

Mass Spectrometric Lipid Profiles of Picosecond Infrared Laser-Generated Tissue Aerosols Discriminate Different Brain Tissues

BACKGROUND AND OBJECTIVES

A picosecond infrared laser (PIRL) has recently been demonstrated to cut biological tissue without scar formation based on the minimal destructive action on the surrounding cells. During cutting with PIRL, the irradiated tissue is ablated by a cold vaporization process termed desorption by impulsive vibrational excitation. In the resulting aerosol, all molecules are dissolved in small droplets and even labile biomolecules like proteins remain intact after ablation. It is hypothesized that these properties enable the PIRL in combination with mass spectrometry as an intelligent laser scalpel for guided surgery. In this study, it was tested if PIRL-generated tissue aerosols are applicable for direct analysis with mass spectrometry, and if the acquired mass spectra can be used to discriminate different brain areas.

MATERIALS AND METHODS

Brain tissues were irradiated with PIRL. The aerosols were collected and directly infused into a mass spectrometer via electrospray ionization without any sample preparation or lipid extraction.

RESULTS

The laser produced clear cuts with no marks of burning. Lipids from five different classes were identified in the mass spectra of all samples. By principal component analysis the different brain areas were clearly distinguishable from each other.

CONCLUSIONS

The results demonstrate the potential for real-time analysis of lipids with a PIRL-based laser scalpel, coupled to a mass spectrometer, for the discrimination of tissues during surgeries. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Cytomegalovirus promotes murine glioblastoma growth via pericyte recruitment and angiogenesis

Cytomegalovirus (CMV) has been implicated in glioblastoma (GBM); however, a mechanistic connection in vivo has not been established. The purpose of this study is to characterize the effects of murine CMV (MCMV) on GBM growth in murine models. Syngeneic GBM models were established in mice perinatally infected with MCMV. We found that tumor growth was markedly enhanced in MCMV+ mice, with a significant reduction in overall survival compared with that of controls (P < 0.001). We observed increased angiogenesis and tumor blood flow in MCMV+ mice. MCMV reactivation was observed in intratumoral perivascular pericytes and tumor cells in mouse and human GBM specimens, and pericyte coverage of tumor vasculature was strikingly augmented in MCMV+ mice. We identified PDGF-D as a CMV-induced factor essential for pericyte recruitment, angiogenesis, and tumor growth. The antiviral drug cidofovir improved survival in MCMV+ mice, inhibiting MCMV reactivation, PDGF-D expression, pericyte recruitment, and tumor angiogenesis. These data show that MCMV potentiates GBM growth in vivo by increased pericyte recruitment and angiogenesis due to alterations in the secretome of CMV-infected cells. Our model provides evidence for a role of CMV in GBM growth and supports the application of antiviral approaches for GBM therapy.

Preclinical investigation of combined gene-mediated cytotoxic immunotherapy and immune checkpoint blockade in glioblastoma

Background

Combined immunotherapy approaches are promising cancer treatments. We evaluated anti-programmed cell death protein 1 (PD-1) treatment combined with gene-mediated cytotoxic immunotherapy (GMCI) performed by intratumoral injection of a prodrug metabolizing nonreplicating adenovirus (AdV-tk), providing in situ chemotherapy and immune stimulation.

Methods

The effects of GMCI on PD ligand 1 (PD-L1) expression in glioblastoma were investigated in vitro and in vivo. The efficacy of the combination was investigated in 2 syngeneic mouse glioblastoma models (GL261 and CT-2A). Immune infiltrates were analyzed by flow cytometry.

Results

GMCI upregulated PD-L1 expression in vitro and in vivo. Both GMCI and anti-PD-1 increased intratumoral T-cell infiltration. A higher percentage of long-term survivors was observed in mice treated with combined GMCI/anti-PD-1 relative to single treatments. Long-term survivors were protected from tumor rechallenge, demonstrating durable memory antitumor immunity. GMCI led to elevated interferon gamma positive T cells and a lower proportion of exhausted double positive PD1+TIM+CD8+ T cells. GMCI also increased PD-L1 levels on tumor cells and infiltrating macrophages/microglia. Our data suggest that anti-PD-1 treatment improves the effectiveness of GMCI by overcoming interferon-induced PD-L1-mediated inhibitory signals, and GMCI improves anti-PD-1 efficacy by increasing tumor-infiltrating T-cell activation.

Conclusions

Our data show that the GMCI/anti-PD-1 combination is well tolerated and effective in glioblastoma mouse models. These results support evaluation of this combination in glioblastoma patients.

MicroRNA-Mediated Dynamic Bidirectional Shift between the Subclasses of Glioblastoma Stem-like Cells

Large-scale transcriptomic profiling of glioblastoma (GBM) into subtypes has provided remarkable insight into the pathobiology and heterogeneous nature of this disease. The mechanisms of speciation and inter-subtype transitions of these molecular subtypes require better characterization to facilitate the development of subtype-specific targeting strategies. The deregulation of microRNA expression among GBM subtypes and their subtype-specific targeting mechanisms are poorly understood. To reveal the underlying basis of microRNA-driven complex subpopulation dynamics within the heterogeneous intra-tumoral ecosystem, we characterized the expression of the subtype-enriched microRNA-128 (miR-128) in transcriptionally and phenotypically diverse subpopulations of patient-derived glioblastoma stem-like cells. Because microRNAs are capable of re-arranging the molecular landscape in a cell-type-specific manner, we argue that alterations in miR-128 levels are a potent mechanism of bidirectional transitions between GBM subpopulations, resulting in intermediate hybrid stages and emphasizing highly intricate intra-tumoral networking.

MicroRNA Signatures and Molecular Subtypes of Glioblastoma: The Role of Extracellular Transfer

Despite the importance of molecular subtype classification of glioblastoma (GBM), the extent of extracellular vesicle (EV)-driven molecular and phenotypic reprogramming remains poorly understood. To reveal complex subpopulation dynamics within the heterogeneous intratumoral ecosystem, we characterized microRNA expression and secretion in phenotypically diverse subpopulations of patient-derived GBM stem-like cells (GSCs). As EVs and microRNAs convey information that rearranges the molecular landscape in a cell type-specific manner, we argue that intratumoral exchange of microRNA augments the heterogeneity of GSC that is reflected in highly heterogeneous profile of microRNA expression in GBM subtypes.

•

MicroRNA signatures reveal tissue heterogeneity in defined glioblastoma subtypes

•

GSC EV/microRNA acts via cell-dependent targeting, propagating intratumoral heterogeneity

•

EV/microRNAs modify molecular landscape, acting in tumor anatomic sites

Abstract B84: Preclinical analysis of combinatorial glioblastoma therapy with the prodrug-mediated gene therapy vector AdV-TK and immune checkpoint inhibition

Early clinical trial data show that blockade of PD-1 signaling leads to significant anticancer responses in a subset of patients in certain cancer types. While the brain has traditionally been considered to be an immune-privileged site, evidence supporting the use of immunotherapeutics in brain tumors has been rapidly accumulating. Given that virus-based cancer therapies can be immunostimulatory and immune checkpoint inhibitors block the body's natural checkpoint response, the combination of these two approaches offers a potentially advantageous interaction. One of the molecular underpinnings of T-cell exhaustion is the expression of Programmed Death-1 (PD-1) on T-cells that recognizes its ligand PD-L1. AdV-TK is an immunostimulatory virus-based approach, known as Gene-Mediated Cytotoxic Immunotherapy (GMCI), that involves the intra-tumoral delivery of a non-replicating adenoviral vector carrying the Herpes virus thymidine kinase gene (TK) followed by administration of an anti-herpetic prodrug (ganciclovir GCV) and recently showed encouraging results in a Phase II trial in glioblastoma (Wheeler et al., 2016). The immunological component results from the delivery vehicle being a virus, the mode of cell death, through both necrosis and apoptosis, and the pro-immunogenic properties of the TK protein. We confirm that this approach induces glioblastoma cell death and a consistent anti-tumor immune stimulation. Not surprisingly, however, this immune stimulation also leads to increase in cell surface of immune checkpoint inhibitory ligands on tumor cells, including PD-L1, detected by flow cytometry and immunohistochemistry. We show that GMCI induces a type-I interferon response, and using IFN decoy we demonstrated that the release of IFNβ in vitro is at least partially responsible for autocrine/paracrine PD-L1 up-regulation both in human and mouse glioblastoma cell lines. In vivo studies using an intracranial GL261 model showed high numbers of long term survivors in the GMCI/PD-1 combination (11/14), compared with GMCI (6/16), anti-PD-1 (5/12) and untreated (0/11). In addition, long term survival mice were no longer able to form tumors after rechallenge indicating the establishment of anti-tumor immunity. Finally, tumor infiltrating lymphocytes after GMCI showed an increase in CD8+, CD8+/GranzymeB+, and IFNγ+ cells suggestive of cytotoxic T-cell activation. However, there was also a significant increase in CD4+, CD4+/FoxP3+, and IL-10 indicating a significant infiltration by Tregs, releasing immunosuppressive cytokines. Additionally, there was a significant increase in PD-1+ /TIM3+ T-cells, indicative of an immunosuppressive microenvironment. Overall, our data show that GMCI/anti-PD-1 combinatorial therapy is effective in a syngeneic tumor model, and strongly support clinical trials of GMCI/checkpoint inhibitor combinations in glioblastoma patients.

Citation Format: Maria Carmela Speranza, Franz Ricklefs, Carmela Passaro, Sarah R. Klein, Kazue Kasai, Johanna Kaufmann, Hiroshi Nakashima, Bronisz Agnieszka, Estuardo Aguilar-Cordova, Brian W. Guzik, Gordon J. Freeman, David A. Reardon, Patrick Wen, E. Antonio Chiocca, Sean E. Lawler. Preclinical analysis of combinatorial glioblastoma therapy with the prodrug-mediated gene therapy vector AdV-TK and immune checkpoint inhibition. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B84.

Abstract A075: Preclinical analysis of combinatorial glioblastoma therapy with the prodrug-mediated gene therapy vector AdV-TK and immune checkpoint inhibition in GBM therapy

While the brain has traditionally been considered to be an immune-privileged site, evidence supporting the use of immunotherapeutics has been rapidly accumulating. Given that virus-based cancer therapies can be immunostimulatory and immune-checkpoint inhibitors block tumor-induced T-cell exhaustion, the combination of these two approaches offers a potentially synergistic interaction. One of the molecular underpinnings of T-cell exhaustion is the expression of Programmed Death-1 (PD1) on T-cells that recognizes its ligand PD-L1. AdV-tk is an immunostimulatory virus-based approach, known as Gene-Mediated Cytotoxic Immunotherapy (GMCI), that involves the intra-tumoral delivery of a non-replicating adenoviral vector carrying the Herpes virus thymidine kinase gene(TK) followed by administration of an anti-herpetic prodrug(ganciclovir-GCV) and recently showed encouraging results in a Phase II trial in glioblastoma(Wheeler et al.,2016). To provide a rationale for this therapeutic combination we investigated PD-L1 expression during GMCI therapy in human and mouse glioma cells in vitro and found that there was a consistent increase in cell surface PD-L1 levels. Interestingly, this was not associated with an increase of mRNA or protein. We also show that GMCI induces a type-I interferon response, and that the release of IFNβ is at least partially responsible for autocrine/paracrine PD-L1 up-regulation. In vivo studies using an intracranial GL261 model showed high levels of long term survivors in the GMCI/PD1 combination (11/14), compared with GMCI (6/16), anti-PD1 (5/12) and controls (0/11). In addition, tumor infiltrating lymphocytes after GMCI showed an increase in CD8+, CD8+/GranzymeB+, and CD8+/IFNγ+/TNFα+cells suggestive of cytotoxic T-cell activation. However, there was also a significant increase in CD4+, CD4+/FoxP3+, and IL-10 indicating a significant infiltration by Tregs, releasing immunosuppressive cytokines. Additionally, there was a significant increase in PD1+/TIM3+ T-cells, indicative of an immunosuppressive microenvironment. Overall, our data show that GMCI/anti-PD1 combinatorial therapy is effective in a syngeneic tumor model, and strongly support clinical trials of GMCI/checkpoint inhibitor combinations in glioblastoma patients.

Citation Format: Maria Carmela Speranza, Kazue Kasai, Franz Ricklefs, Sarah R. Klein, Carmela Passaro, Hiroshi Nakashima, Johanna Kaufmann, Agnieszka Bronisz, Estuardo Aguilar-Cordova, Brian W. Guzik, Gordon J. Freeman, David A. Reardon, Patrick Wen, E. Antonio Chiocca, Sean E. Lawler. Preclinical analysis of combinatorial glioblastoma therapy with the prodrug-mediated gene therapy vector AdV-TK and immune checkpoint inhibition in GBM therapy [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A075.

Abstract 1000: The long non-coding RNA HIF1A-AS2 regulates mesenchymal glioma stem cell tumorigenicity

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults, which initiation and progression is driven by a subset of self-renewing GBM stem-like cells (GSCs). Long-non coding RNAs (lncRNAs) have been recently shown to play important roles in regulating numerous biological processes both in physiologic and pathologic condition. Identification of functional lncRNAs important for GBM initiation and progression may shed new light on understanding pathophysiology of the disease. We used a custom made lncRNA Nanostring platform to profile the expression of lncRNAs in subtype-characterized collection of patient-derived GSCs. We demonstrated that lncRNA signature may distinguish between GSC subtypes. Out of 73 lncRNAs we found 7 that were overexpressed specifically in the most aggressive mesenchymal (M) GSC subtype. Among them, HIF1A-AS2 was the most differentially expressed lncRNA. HIF1A-AS2 was reported to be overexpressed in many types of cancers; however its biological function and its role in GBM progression are unknown. Knockdown of HIF1A-AS2 in M GSCs resulted in reduced growth, increased cytotoxicity, and it strongly inhibited their neurosphere formation capability. Using more global approach we found out that knockdown of HIF1A-AS2 in M GSCs caused deregulation of several out of 730 cancer-related genes. Functional bioinformatic analysis revealed that these differentially expressed mRNAs are closely related to proliferation, transcriptional regulation and cell division. RNA pull-down assay showed that HIF1A-AS2 may exert its effects through specific binding of RNA helicase DHX9, a multifunctional protein with important roles in transcription, pre-mRNA processing and translation. We also demonstrated that HMGA1, a gene known to be regulated by DHX9, was specifically down-regulated in HIF1A-AS2 knockdown cells both at mRNA and protein level. Finally, we showed that silencing of HIF1A-AS2 blocked M GSC tumor growth in vivo resulting in significant survival benefits. Taken together, our results suggest HIF1A-AS2 as an important lncRNA in pathophysiology of GBM.

Citation Format: Marco Mineo, Franz Ricklefs, Arun Rooj, Shawn M. Lyons, Pavel Ivanov, Ennio A. Chiocca, Jakub Godlewski, Agnieszka Bronisz. The long non-coding RNA HIF1A-AS2 regulates mesenchymal glioma stem cell tumorigenicity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1000.

Abstract 1929: The novel role of microRNA-128 in proneural to mesenchymal subtype transition in glioblastoma stem cells by targeting components of pro-oncogenic Polycomb Repressor Complex

Heterogeneous glioblastoma multiforme (GBM) was categorized based on transcriptional signatures into four subtypes (proneural (PN), neural, classical, and mesenchymal (MES)). In order to develop effective targeted therapeutic strategies, understanding the heterogeneous gene expression and molecular features of these subtypes is crucial. De-regulation of microRNA expression and activity has been shown to play an important role in tumor initiation and progression, including gliomagenesis. We have previously reported that expression of microRNA-128 (miR-128) is significantly down regulated in GBM and it diminishes self-renewal of GBM stem-like cells (GSCs) and sensitizes them to irradiation. Proneural-to-mesenchymal transition (PMT) manifested by concomitant up regulation of MES markers and down regulation of PN markers, is associated with increased malignancy, therapy-resistance and worse prognosis, but the underlying causes of PMT have not been convincingly characterized yet. In this study, we have demonstrated that miR-128 can regulate the PMT in GSC subsets. We showed that the expression of miR-128 in PN GSCs was significantly higher compared to MES subtype. As a tumor suppressive microRNA, miR-128 inhibited the MES GSC-specific high expression of Bmi1 and Suz12, two components of Polycomb Repressor Complexes (PRC) 1 and 2, respectively. In both GSC subtypes, miR-128 driven targeting of PRCs suppressed their epigenetic activity measured by ubiquitination of H2AK119 and tri-methylation of H3K27. Stable down regulation of miR-128 in PN GSCs significantly increased the expression of MES-specific gene signature (BCL2A1, CD44, WT-1, LYN, and MET) while its stable up regulation in MES GSCs resulted in the restoration of PN specific gene signature (CD133, SOX2, NES, OLIG2, and NOTCH1). We also showed that stable expression of miR-128 in GSCs could regulate the process of irradiation-induced PMT. Our in vivo studies showed the anti-tumorigenic role of miR-128 in both PN and MES GSC-derived intracranial tumor models. Taken together, we demonstrated that altering levels of miR-128 was sufficient to cause or reverse PMT, most likely by targeting the level/functions of PRCs and their target genes in GBM.

Citation Format: Arun K. Rooj, Marco Mineo, Franz Ricklefs, Agnieszka Bronisz, Ennio Chiocca, Jakub Godlewski. The novel role of microRNA-128 in proneural to mesenchymal subtype transition in glioblastoma stem cells by targeting components of pro-oncogenic Polycomb Repressor Complex. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1929.

The Long Non-coding RNA HIF1A-AS2 Facilitates the Maintenance of Mesenchymal Glioblastoma Stem-like Cells in Hypoxic Niches

Long non-coding RNAs (lncRNAs) have an undefined role in the pathobiology of glioblastoma multiforme (GBM). These tumors are genetically and phenotypically heterogeneous with transcriptome subtype-specific GBM stem-like cells (GSCs) that adapt to the brain tumor microenvironment, including hypoxic niches. We identified hypoxia-inducible factor 1 alpha-antisense RNA 2 (HIF1A-AS2) as a subtype-specific hypoxia-inducible lncRNA, upregulated in mesenchymal GSCs. Its deregulation affects GSC growth, self-renewal, and hypoxia-dependent molecular reprogramming. Among the HIF1A-AS2 interactome, IGF2BP2 and DHX9 were identified as direct partners. This association was needed for maintenance of expression of their target gene, HMGA1. Downregulation of HIF1A-AS2 led to delayed growth of mesenchymal GSC tumors, survival benefits, and impaired expression of HMGA1 in vivo. Our data demonstrate that HIF1A-AS2 contributes to GSCs' speciation and adaptation to hypoxia within the tumor microenvironment, acting directly through its interactome and targets and indirectly by modulating responses to hypoxic stress depending on the subtype-specific genetic context.

Extracellular Vesicles from High-Grade Glioma Exchange Diverse Pro-oncogenic Signals That Maintain Intratumoral Heterogeneity

A lack of experimental models of tumor heterogeneity limits our knowledge of the complex subpopulation dynamics within the tumor ecosystem. In high-grade gliomas (HGG), distinct hierarchical cell populations arise from different glioma stem-like cell (GSC) subpopulations. Extracellular vesicles (EV) shed by cells may serve as conduits of genetic and signaling communications; however, little is known about how HGG heterogeneity may impact EV content and activity. In this study, we performed a proteomic analysis of EVs isolated from patient-derived GSC of either proneural or mesenchymal subtypes. EV signatures were heterogeneous, but reflected the molecular make-up of the GSC and consistently clustered into the two subtypes. EV-borne protein cargos transferred between proneural and mesenchymal GSC increased protumorigenic behaviors in vitro and in vivo Clinically, analyses of HGG patient data from the The Cancer Genome Atlas database revealed that proneural tumors with mesenchymal EV signatures or mesenchymal tumors with proneural EV signatures were both associated with worse outcomes, suggesting influences by the proportion of tumor cells of varying subtypes in tumors. Collectively, our findings illuminate the heterogeneity among tumor EVs and the complexity of HGG heterogeneity, which these EVs help to maintain. Cancer Res; 76(10); 2876-81. ©2016 AACR.

Abstract PR04: The role of long noncoding RNA HIF1A-AS2 in hypoxic environment of glioblastoma

Purpose: While multiple protein-coding genes are known to play a crucial role in the formation and progression of glioblastoma multiforme (GBM), the role of long-non-coding RNAs (lncRNAs) in these cascades remains to be fully characterized. Considering the fundamental roles of hypoxia in the cellular and microenvironmental complexity and unexplored function of lncRNAs in GBM pathobiology, the identification of novel lncRNAs and their target pathways that drive the adaptation to hypoxic niche is crucial for better understanding of the development and progression of this highly heterogeneous brain tumor. Transcriptome profiling of GBM have revealed the presence of four clearly distinguishable subtypes, variably expressed in individual cells within a tumor. This finding may have potential clinical implications, including subtype-specific rearrangements of transcriptional programs related to oncogenic signaling, growth and hypoxia. However, the subtype-specific role of lncRNAs in tumorigenic potential of GBM subtypes remains largely unknown.

Materials and Methods: The brain tissue samples including GBM tumors and non-pathological tissue adjacent to the tumor were collected. GBM-derived primary stem cells (GSCs) classified by transcriptome analysis as proneural (P) and mesenchymal (M), were collected and exposed to hypoxic conditions. Using custom designed Nanostring platform analysis followed by qPCR, the expression patterns of 70 cancer-related lncRNAs were characterized. The in situ hybridization and qPCR analysis was used to validate sub-cellular localization of selected lncRNA. RNA immunoprecipitation (RIP) and mass-spectroscopy (MS) was performed to map RNA-protein interaction and identified targets were validated by Western blotting. The global GSC transcriptome profiling upon lncRNA de-regulation was performed using Pan Cancer Nanostring platform. The knock-down and overexpression strategies in GSC were used to characterize cellular and molecular phenotypes in vitro and in in vivo intracranial GBM model.

Results: We identified lncRNA HIF1A-AS2 (Hypoxia Inducible Factor 1 alpha - antisense 2) as one of the most deregulated in GBM comparing to the matched adjacent tissue. Despite lack of difference in the hypoxia-dependent activation of HIF1A protein between P and M GSC, HIF1A-AS2 was specifically upregulated in M GSC in vitro and in vivo. The deregulation of expression of HIF1A-AS2 had a broad effect on autophagy-related signaling network regulated in response to hypoxia in M but not P GSC. The IGF2BP2 and DHX9 were identified as direct protein partners of this lncRNA. The deregulation of HIF1A-AS2 affected the recruitment of IGF2BP2 to its mRNA targets (e.g. HMG1) and stability of DHX9 protein (but not mRNA), resulting in deregulation of its target genes (e.g FOSL1). Downregulation of HIF1A-AS2 in vivo led to de-regulation of its downstream effectors and resulted in survival benefit of mice bearing M GSC-originated tumors.

Conclusion: P and M GSC respond differently to hypoxic stress by induction of autophagy to maintain their homeostasis and viability and this mechanism is controlled by HIF1A-AS2.

This abstract is also presented as Poster A16.

Citation Format: Marco Mineo, Franz Ricklefs, Shawn S. Lyons, Pavel Ivanov, E. Antonio Chiocca, Jakub Godlewski, Agnieszka Bronisz. The role of long noncoding RNA HIF1A-AS2 in hypoxic environment of glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer: Mechanisms to Medicines ; 2015 Dec 4-7; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2016;76(6 Suppl):Abstract nr PR04.

The simplified acute physiology score II to predict hospital mortality in aneurysmal subarachnoid hemorrhage

BACKGROUND

Early prediction of increased morbidity and mortality in aneurysmal subarachnoid hemorrhage (aSAH) remains crucial to improving patient management. Most prediction models lack external validation and focus on disease-specific items without considering physiological parameters and the past medical history. The aim was to assess the validity of the established Simplified Acute Physiology Score II (SAPS-II) in an aSAH cohort for the prediction of hospital mortality and to identify additional physiological and clinical predictors.

METHODS

The predictive value of SAPS-II for hospital mortality was assessed in a retrospective analysis of 263 consecutive patients with aSAH. Additional physiological and clinical parameters including the past medical history were analyzed by forward selection multivariate analysis to identify independent predictors of hospital mortality and to improve the prediction model.

RESULTS

The SAPS-II predicted hospital mortality with an area under the curve (AUC) of 0.834 with an odds ratio (OR) of 1.097 [95 % confidence interval 1.067-1.128) for each additional point. Forward selection multivariate analysis identified the Glasgow Coma Scale score (P < 0.001), history of chronic headache (P = 0.01) and medication with anticoagulants (P = 0.04) as independent predictors of hospital mortality. Adding these parameters to the SAPS-II, the AUC increased to 0.86.

CONCLUSION

This study validates the predictive accuracy of SAPS-II for hospital mortality in aSAH patients. Additional parameters from the past medical history increase its predictive power. From a practical viewpoint, SAPS-II alone already represents a sufficient and powerful score to predict hospital mortality at an early time point and may help to improve patient management.