RT-PCR assay to detect FGFR3::TACC3 fusions in formalin-fixed, paraffin-embedded glioblastoma samples

Background

One targeted treatment option for isocitrate dehydrogenase (IDH)-wild-type glioblastoma focuses on tumors with fibroblast growth factor receptor 3::transforming acidic coiled-coil-containing protein 3 (FGFR3::TACC3) fusions. FGFR3::TACC3 fusion detection can be challenging, as targeted RNA next-generation sequencing (NGS) is not routinely performed, and immunohistochemistry is an imperfect surrogate marker. Fusion status can be determined using reverse transcription polymerase chain reaction (RT-PCR) on fresh frozen (FF) material, but sometimes only formalin-fixed, paraffin-embedded (FFPE) tissue is available.

Aim

To develop an RT-PCR assay to determine FGFR3::TACC3 status in FFPE glioblastoma samples.

Methods

Twelve tissue microarrays with 353 historical glioblastoma samples were immunohistochemically stained for FGFR3. Samples with overexpression of FGFR3 (n = 13) were subjected to FGFR3::TACC3 RT-PCR on FFPE, using 5 primer sets for the detection of 5 common fusion variants. Fusion-negative samples were additionally analyzed with NGS (n = 6), FGFR3 Fluorescence In Situ Hybridization (n = 6), and RNA sequencing (n = 5).

Results

Using RT-PCR on FFPE material of the 13 samples with FGFR3 overexpression, we detected an FGFR3::TACC3 fusion in 7 samples, covering 3 different fusion variants. For 5 of these FF was available, and the presence of the fusion was confirmed through RT-PCR on FF. With RNA sequencing, 1 additional sample was found to harbor an FGFR3::TACC3 fusion (variant not covered by current RT-PCR for FFPE). The frequency of FGFR3::TACC3 fusion in this cohort was 9/353 (2.5%).

Conclusions

RT-PCR for FGFR3::TACC3 fusions can successfully be performed on FFPE material, with a specificity of 100% and (due to limited primer sets) a sensitivity of 83.3%. This assay allows for the identification of potential targeted treatment options when only formalin-fixed tissue is available.

Preserving the ability to discriminate between left and right; A case study

Left-right orientation, a function related to the parietal lobe, is important for many daily activities. Here, we describe a left-handed patient with a right parietal brain tumour. During awake surgery, electric stimulation of the right inferior parietal lobe resulted in mistakes in his left-right orientation. Postoperatively our patient had no problems in discriminating left right. This case report shows that monitoring of left-right orientation during awake brain tumour surgery is feasible so that this function can be preserved.

Limited Effects of Class II Transactivator-Based Immunotherapy in Murine and Human Glioblastoma

BACKGROUND

The major histocompatibility complex type II is downregulated in glioblastoma (GB) due to the silencing of the major transcriptional regulator class II transactivator (CIITA). We investigated the pro-immunogenic potential of CIITA overexpression in mouse and human GB.

METHODS

The intracerebral growth of wildtype GL261-WT cells was assessed following contralateral injection of GL261-CIITA cells or flank injections with GL261-WT or GL261-CIITA cells. Splenocytes obtained from mice implanted intracerebrally with GL261-WT, GL261-CIITA cells or phosphate buffered saline (PBS) were transferred to other mice and subsequently implanted intracerebrally with GL261-WT. Human GB cells and (syngeneic) GB-infiltrating immune cells were isolated from surgical samples and co-cultured with GB cells expressing CIITA or not, followed by RT-qPCR assessment of the expression of key immune regulators.

RESULTS

Intracerebral vaccination of GL261-CIITA significantly reduced the subsequent growth of GL261-WT cells implanted contralaterally. Vaccination with GL261-WT or -CIITA subcutaneously, however, equivalently retarded the intracerebral growth of GL261 cells. Adoptive cell transfer experiments showed a similar antitumor potential of lymphocytes harvested from mice implanted intracerebrally with GL261-WT or -CIITA. Human GB-infiltrating myeloid cells and lymphocytes were not activated when cultured with CIITA-expressing GB cells. Tumor-infiltrating NK cells remained mostly inactivated when in co-culture with GB cells, regardless of CIITA.

CONCLUSION

these results question the therapeutic potential of CIITA-mediated immunotherapy in glioblastoma.

Evaluation Metrics for Augmented Reality in Neurosurgical Preoperative Planning, Surgical Navigation, and Surgical Treatment Guidance: A Systematic Review

BACKGROUND AND OBJECTIVE

Recent years have shown an advancement in the development of augmented reality (AR) technologies for preoperative visualization, surgical navigation, and intraoperative guidance for neurosurgery. However, proving added value for AR in clinical practice is challenging, partly because of a lack of standardized evaluation metrics. We performed a systematic review to provide an overview of the reported evaluation metrics for AR technologies in neurosurgical practice and to establish a foundation for assessment and comparison of such technologies.

METHODS

PubMed, Embase, and Cochrane were searched systematically for publications on assessment of AR for cranial neurosurgery on September 22, 2022. The findings were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

The systematic search yielded 830 publications; 114 were screened full text, and 80 were included for analysis. Among the included studies, 5% dealt with preoperative visualization using AR, with user perception as the most frequently reported metric. The majority (75%) researched AR technology for surgical navigation, with registration accuracy, clinical outcome, and time measurements as the most frequently reported metrics. In addition, 20% studied the use of AR for intraoperative guidance, with registration accuracy, task outcome, and user perception as the most frequently reported metrics.

CONCLUSION

For quality benchmarking of AR technologies in neurosurgery, evaluation metrics should be specific to the risk profile and clinical objectives of the technology. A key focus should be on using validated questionnaires to assess user perception; ensuring clear and unambiguous reporting of registration accuracy, precision, robustness, and system stability; and accurately measuring task performance in clinical studies. We provided an overview suggesting which evaluation metrics to use per AR application and innovation phase, aiming to improve the assessment of added value of AR for neurosurgical practice and to facilitate the integration in the clinical workflow.

Multi-class glioma segmentation on real-world data with missing MRI sequences: comparison of three deep learning algorithms

This study tests the generalisability of three Brain Tumor Segmentation (BraTS) challenge models using a multi-center dataset of varying image quality and incomplete MRI datasets. In this retrospective study, DeepMedic, no-new-Unet (nn-Unet), and NVIDIA-net (nv-Net) were trained and tested using manual segmentations from preoperative MRI of glioblastoma (GBM) and low-grade gliomas (LGG) from the BraTS 2021 dataset (1251 in total), in addition to 275 GBM and 205 LGG acquired clinically across 12 hospitals worldwide. Data was split into 80% training, 5% validation, and 15% internal test data. An additional external test-set of 158 GBM and 69 LGG was used to assess generalisability to other hospitals' data. All models' median Dice similarity coefficient (DSC) for both test sets were within, or higher than, previously reported human inter-rater agreement (range of 0.74-0.85). For both test sets, nn-Unet achieved the highest DSC (internal = 0.86, external = 0.93) and the lowest Hausdorff distances (10.07, 13.87 mm, respectively) for all tumor classes (p < 0.001). By applying Sparsified training, missing MRI sequences did not statistically affect the performance. nn-Unet achieves accurate segmentations in clinical settings even in the presence of incomplete MRI datasets. This facilitates future clinical adoption of automated glioma segmentation, which could help inform treatment planning and glioma monitoring.

Segmentation of glioblastomas in early post-operative multi-modal MRI with deep neural networks

Extent of resection after surgery is one of the main prognostic factors for patients diagnosed with glioblastoma. To achieve this, accurate segmentation and classification of residual tumor from post-operative MR images is essential. The current standard method for estimating it is subject to high inter- and intra-rater variability, and an automated method for segmentation of residual tumor in early post-operative MRI could lead to a more accurate estimation of extent of resection. In this study, two state-of-the-art neural network architectures for pre-operative segmentation were trained for the task. The models were extensively validated on a multicenter dataset with nearly 1000 patients, from 12 hospitals in Europe and the United States. The best performance achieved was a 61% Dice score, and the best classification performance was about 80% balanced accuracy, with a demonstrated ability to generalize across hospitals. In addition, the segmentation performance of the best models was on par with human expert raters. The predicted segmentations can be used to accurately classify the patients into those with residual tumor, and those with gross total resection.

PET Imaging and Protein Expression of Prostate-Specific Membrane Antigen in Glioblastoma: A Multicenter Inventory Study

Upregulation of prostate-specific membrane antigen (PSMA) in neovasculature has been described in glioblastoma multiforme (GBM), whereas vasculature in nonaffected brain shows hardly any expression of PSMA. It is unclear whether PSMA-targeting tracer uptake on PET is based on PSMA-specific binding to neovasculature or aspecific uptake in tumor. Here, we quantified uptake of various PSMA-targeting tracers in GBM and correlated this with PSMA expression in tumor biopsy samples from the same patients. Methods: Fourteen patients diagnosed with de novo (n = 8) or recurrent (n = 6) GBM underwent a preoperative PET scan after injection of 1.5 MBq/kg [68Ga]Ga-PSMA-11 (n = 7), 200 MBq of [18F]DCFpyl (n = 3), or 200 MBq of [18F]PSMA-1007 (n = 4). Uptake in tumor and tumor-to-background ratios, with contralateral nonaffected brain as background, were determined. In a subset of patients, PSMA expression levels from different regions in the tumor tissue samples (n = 40), determined using immunohistochemistry (n = 35) or RNA sequencing (n = 13), were correlated with tracer uptake on PET. Results: Moderate to high (SUVmax, 1.3-20.0) heterogeneous uptake was found in all tumors irrespective of the tracer type used. Uptake in nonaffected brain was low, resulting in high tumor-to-background ratios (6.1-359.0) calculated by dividing SUVmax of tumor by SUVmax of background. Immunohistochemistry showed variable PSMA expression on endothelial cells of tumor microvasculature, as well as on dispersed individual cells (of unknown origin), and granular staining of the neuropil. No correlation was found between in vivo uptake and PSMA expression levels (for immunohistochemistry, r = -0.173, P = 0.320; for RNA, r = -0.033, P = 0.915). Conclusion: Our results indicate the potential use of various PSMA-targeting tracers in GBM. However, we found no correlation between PSMA expression levels on immunohistochemistry and uptake intensity on PET. Whether this may be explained by methodologic reasons, such as the inability to measure functionally active PSMA with immunohistochemistry, tracer pharmacokinetics, or the contribution of a disturbed blood-brain barrier to tracer retention, should still be investigated.

Awake craniotomy does not lead to increased psychological complaints

BACKGROUND

Patients with brain tumours are increasingly treated by using the awake craniotomy technique. Some patients may experience anxiety when subjected to brain surgery while being fully conscious. However, there has been only limited research into the extent to which such surgeries actually result in anxiety or other psychological complaints. Previous research suggests that undergoing awake craniotomy surgery does not lead to psychological complaints, and that post-traumatic stress disorders (PTSD) are uncommon following this type of surgery. It must be noted, however, that many of these studies used small random samples.

METHOD

In the current study, 62 adult patients completed questionnaires to identify the degree to which they experienced anxiety, depressive and post-traumatic stress complaints following awake craniotomy using an awake-awake-awake procedure. All patients were cognitively monitored and received coaching by a clinical neuropsychologist during the surgery.

RESULTS

In our sample, 21% of the patients reported pre-operative anxiety. Four weeks after surgery, 19% of the patients reported such complaints, and 24% of the patients reported anxiety complaints after 3 months. Depressive complaints were present in 17% (pre-operative), 15% (4 weeks post-operative) and 24% (3 months post-operative) of the patients. Although there were some intra-individual changes (improvement or deterioration) in the psychological complaints over time, on group-level postoperative levels of psychological complaints were not increased relative to the preoperative level of complaints. The severity of post-operative PTSD-related complaints were rarely suggestive of a PTSD. Moreover, these complaints were seldom attributed to the surgery itself, but appeared to be more related to the discovery of the tumour and the postoperative neuropathological diagnosis.

CONCLUSIONS

The results of the present study do not indicate that undergoing awake craniotomy is associated with increased psychological complaints. Nevertheless, psychological complaints may well exist as a result of other factors. Consequently, monitoring the patient's mental wellbeing and offering psychological support where necessary remain important.

Study protocol for a multicenter randomised controlled trial on the (cost)effectiveness of biopsy combined with same-session MR-guided LITT versus biopsy alone in patients with primary irresectable glioblastoma (EMITT trial)

BACKGROUND

Glioblastoma (GBM) is the most common primary, malignant brain tumour with a 5-year survival of 5%. If possible, a glioblastoma is resected and further treated with chemoradiation therapy (CRT), but resection is not feasible in about 30% of cases. Current standard of care in these cases is a biopsy followed by CRT. Magnetic resonance (MR) imaging-guided laser interstitial thermal therapy (LITT) has been suggested as a minimally invasive alternative when surgery is not feasible. However, high-quality evidence directly comparing LITT with standard of care is lacking, precluding any conclusions on (cost-)effectiveness. We therefore propose a multicenter randomized controlled study to assess the (cost-)effectiveness of MR-guided LITT as compared to current standard of care (EMITT trial).

METHODS AND ANALYSIS

The EMITT trial will be a multicenter pragmatic randomized controlled trial in the Netherlands. Seven Dutch hospitals will participate in this study. In total 238 patients will be randomized with 1:1 allocation to receive either biopsy combined with same-session MR-guided LITT therapy followed by CRT or the current standard of care being biopsy followed by CRT. The primary outcomes will be health-related quality of life (HR-QoL) (non-inferiority) using EORTC QLQ-C30 + BN20 scores at 5 months after randomization and overall survival (superiority). Secondary outcomes comprise cost-effectiveness (healthcare and societal perspective) and HR-QoL of life over an 18-month time horizon, progression free survival, tumour response, disease specific survival, longitudinal effects, effects on adjuvant treatment, ablation percentage and complication rates.

DISCUSSION

The EMITT trial will be the first RCT on the effectiveness of LITT in patients with glioblastoma as compared with current standard of care. Together with the Dutch Brain Tumour Patient association, we hypothesize that LITT may improve overall survival without substantially affecting patients' quality of life.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov (NCT05318612).

TRIB1 confers therapeutic resistance in GBM cells by activating the ERK and Akt pathways

GBM (Glioblastoma) is the most lethal CNS (Central nervous system) tumor in adults, which inevitably develops resistance to standard treatments leading to recurrence and mortality. TRIB1 is a serine/threonine pseudokinase which functions as a scaffold platform that initiates degradation of its substrates like C/EBPα through the ubiquitin proteasome system and also activates MEK and Akt signaling. We found that increased TRIB1 gene expression associated with worse overall survival of GBM patients across multiple cohorts. Importantly, overexpression of TRIB1 decreased RT/TMZ (radiation therapy/temozolomide)-induced apoptosis in patient derived GBM cell lines in vitro. TRIB1 directly bound to MEK and Akt and increased ERK and Akt phosphorylation/activation. We also found that TRIB1 protein expression was maximal during G2/M transition of cell cycle in GBM cells. Furthermore, TRIB1 bound directly to HDAC1 and p53. Importantly, mice bearing TRIB1 overexpressing tumors had worse overall survival. Collectively, these data suggest that TRIB1 induces resistance of GBM cells to RT/TMZ treatments by activating the cell proliferation and survival pathways thus providing an opportunity for developing new targeted therapeutics.

Cosmetic satisfaction and patient-reported outcome measures following cranioplasty after craniectomy - A prospective cohort study

Introduction

Evaluating patient-reported outcomes (PROMs) helps optimize preoperative counseling and psychosocial care for patients who underwent cranioplasty.

Research question

This study aimed to evaluate cosmetic satisfaction, level of self-esteem, and fear of negative evaluation (FNE) of patients who underwent cranioplasty.

Material and methods

Patients who underwent cranioplasty from 1 January 2014 to 31 December 2020 ​at University Medical Center Utrecht and a control group consisting of our center' employees were invited to fill out the Craniofacial Surgery Outcomes Questionnaire (CSO-Q), consisting of an assessment of cosmetic satisfaction, the Rosenberg Self-Esteem Scale (RSES), and the FNE scale. To test for differences in results, chi-square tests and T-tests were performed. Logistic regression was used to study the effect of cranioplasty-related variables on cosmetic satisfaction.

Results

Cosmetic satisfaction was seen in 44/80 patients (55.0%) and 52/70 controls (74.3%) (p ​= ​0.247). Thirteen patients (16.3%) and 8 controls (11.4%) had high self-esteem (p ​= ​0.362), 51 patients (63.8%) and 59 controls (84.3%) had normal self-esteem (p ​= ​0.114), and 7 patients (8.8%) and 3 controls (4.3%) had low self-esteem (p ​= ​0.337). Forty-nine patients (61.3%) and 39 controls (55.7%) had low FNE (p ​= ​0.012), 8 patients (10.0%) and 18 controls (25.7%) had average FNE (p ​= ​0.095), and 6 patients (7.5%) and 13 controls (18.6%) had high FNE (p ​= ​0.215). Cosmetic satisfaction was associated with glass fiber-reinforced composite implants (OR 8.20, p-value ​= ​0.04).

Discussion and conclusion

This study prospectively evaluated PROMs following cranioplasty, for which we found favorable results.

Risk Factors and Management of Incisional Cerebrospinal Fluid Leakage After Craniotomy: A Retrospective International Multicenter Study

BACKGROUND

Incisional cerebrospinal fluid (iCSF) leakage is a serious complication after intradural cranial surgery.

OBJECTIVE

To determine the incidence and risk factors of iCSF leakage after craniotomy. Secondarily, the complications after iCSF leakage and the success rate of iCSF leakage treatment was studied.

METHODS

All patients who underwent an intradural cranial surgery from 2017 to 2018 at 5 neurosurgical centers were retrospectively included. Data were retrieved from medical records with 2 months of follow-up. First, univariate regression analyses were performed. Subsequently, identified risk factors were evaluated in a multivariate regression analysis.

RESULTS

In total 2310 consecutive patients were included. Total iCSF leakage rate was 7.1% (n = 165). Younger age, male, higher body mass index, smoking, infratentorial surgery, and use of a dural substitute were associated with increased iCSF leakage risk, and use of a sealant reduced that risk. The odds for developing a wound infection and/or meningitis were 15 times higher in patients with iCSF leakage compared with patients without leakage. Initial conservative iCSF leakage treatment failed in 48% of patients. In 80% of cases, external cerebrospinal fluid drainage ceased the iCSF leakage. A total of 32% of patients with iCSF leakage required wound revision surgery.

CONCLUSION

iCSF leakage risk increases by younger age, higher body mass index, smoking, infratentorial craniotomy, and dural substitute use, whereas sealant use reduced the risk for iCSF leakage. The leak increases the risk of postoperative infections. When iCSF leakage occurs, immediate external cerebrospinal fluid drainage or wound revision should be considered.

Development of a Prediction Model for Cranioplasty Implant Survival Following Craniectomy

BACKGROUND

Cranioplasty following craniectomy can imply high rates of postoperative complications. While determinants of postoperative outcomes have been identified, a prediction model for predicting cranioplasty implant survival does not exist.

OBJECTIVE

To develop a prediction model for cranioplasty implant survival following craniectomy.

METHODS

We performed a retrospective cohort study of patients who underwent cranioplasty following craniectomy between 2014 and 2020. Missing data were imputed using multiple imputation. For model development, multivariable Cox proportional hazards regression analysis was performed. To test whether candidate determinants contributed to the model, we performed backward selection using Akaike Information Criterion. We corrected for overfitting using bootstrapping techniques. The performance of the model was assessed using discrimination and calibration.

RESULTS

A total of 182 patients were included (mean age 43.0 ± 19.7 years). Independent determinants of cranioplasty implant survival included indication for craniectomy (compared with trauma: vascular disease HR 0.65 [95% CI 0.36 - 1.17], infection HR 0.76 [95% CI 0.32 - 1.80], tumor HR 1.40 [95% CI 0.29 - 6.79]), cranial defect size (HR 1.01 per cm² [95% CI 0.73 - 1.38]), use of an autologous bone flap (HR 1.63 [95% CI 0.82 - 3.24]), and skin closure using staples (HR 1.42 [95% CI 0.79 - 2.56]). The c-index of the model was 0.60 (95% CI 0.47 - 0.73).

CONCLUSION

We developed the first prediction model for cranioplasty implant survival following craniectomy. The findings in this study require external validation and deserve further exploration in future studies.

Transcriptome analysis reveals tumor microenvironment changes in glioblastoma

A better understanding of transcriptional evolution of IDH-wild-type glioblastoma may be crucial for treatment optimization. Here, we perform RNA sequencing (RNA-seq) (n = 322 test, n = 245 validation) on paired primary-recurrent glioblastoma resections of patients treated with the current standard of care. Transcriptional subtypes form an interconnected continuum in a two-dimensional space. Recurrent tumors show preferential mesenchymal progression. Over time, hallmark glioblastoma genes are not significantly altered. Instead, tumor purity decreases over time and is accompanied by co-increases in neuron and oligodendrocyte marker genes and, independently, tumor-associated macrophages. A decrease is observed in endothelial marker genes. These composition changes are confirmed by single-cell RNA-seq and immunohistochemistry. An extracellular matrix-associated gene set increases at recurrence and bulk, single-cell RNA, and immunohistochemistry indicate it is expressed mainly by pericytes. This signature is associated with significantly worse survival at recurrence. Our data demonstrate that glioblastomas evolve mainly by microenvironment (re-)organization rather than molecular evolution of tumor cells.

Occurrence, Risk Factors, and Consequences of Postoperative Ischemia After Glioma Resection: A Retrospective Study

BACKGROUND

Postoperative ischemia can lead to neurological deficits and is a known complication of glioma resection. There is inconsistency in documented incidence of ischemia after glioma resection, and the precise cause of ischemia is often unknown.

OBJECTIVE

To assess the incidence of postoperative ischemia and neurological deficits after glioma resection and to evaluate their association with potential risk factors.

METHODS

One hundred thirty-nine patients with 144 surgeries between January 2012 and September 2014 for World Health Organization (WHO) 2016 grade II-IV diffuse supratentorial gliomas with postoperative MRI within 72 hours were retrospectively included. Patient, tumor, and perioperative data were extracted from the electronic patient records. Occurrence of postoperative confluent ischemia, defined as new confluent areas of diffusion restriction, and new or worsened neurological deficits were analyzed univariably and multivariably using logistic regression models.

RESULTS

Postoperative confluent ischemia was found in 64.6% of the cases. Occurrence of confluent ischemia was associated with an insular location ( P = .042) and intraoperative administration of vasopressors ( P = .024) in multivariable analysis. Glioma location in the temporal lobe was related to an absence of confluent ischemia ( P = .01). Any new or worsened neurological deficits occurred in 30.6% and 20.9% at discharge from the hospital and at first follow-up, respectively. Occurrence of ischemia was significantly associated with the presence of novel neurological deficits at discharge ( P = .013) and after 3 months ( P = .024).

CONCLUSION

Postoperative ischemia and neurological deficit were significantly correlated. Intraoperative administration of vasopressors, insular glioma involvement, and absence of temporal lobe involvement were significantly associated with postoperative ischemia.

STAT5b is a marker of poor prognosis, rather than a therapeutic target in glioblastomas

The copy number and mRNA expression of STAT5b were assessed in samples from the TCGA repository of glioblastomas (GBM). The activation of this transcription factor was analyzed on tissue microarrays comprising 392 WHO 2016 GBM samples from our clinical practice. These data were correlated with patient survival using multivariable Cox analysis and, for a subset of 167 tumors, with signs of tumor invasiveness on the MRI. The effects of STAT5b knockdown by siRNA were assessed on the growth, therapeutic resistance, invasion and migration of GBM cell lines U87, U87-EGFRVIII and LN18 and primary cultures GM2 and GM3. The activation, but not the copy number or the mRNA expression of nuclear transcription factor STAT5b expression correlated inversely with patient survival independently of IDH1R132H status, age, Karnofsky Performance Score, treatment and tumor volume. STAT5b inhibition neither altered the cell proliferation nor reduced the clonogenic proliferative potency of GBM cells, and did not sensitize them to the cytotoxic effect of ionizing radiation and temozolomide in vitro. STAT5b inhibition significantly increased GBM cell migration, but decreased the invasion of some GBM cells in vitro. There was no correlation between the activation of STAT5b in clinical tumors and the extent of invasion on MRI OF patients. In conclusion, STAT5b is frequently activated in GBM and correlates inversely with patient survival. It does not contribute to the growth and resistance of these tumors, and is thus rather a potential prognostic marker than a therapeutic target in these tumors.

MR Imaging and Clinical Characteristics of Diffuse Glioneuronal Tumor with Oligodendroglioma-like Features and Nuclear Clusters

BACKGROUND AND PURPOSE

Diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters (DGONC) is a new, molecularly defined glioneuronal CNS tumor type. The objective of the present study was to describe MR imaging and clinical characteristics of patients with DGONC.

MATERIALS AND METHODS

Preoperative MR images of 9 patients with DGONC (median age at diagnosis, 9.9 years; range, 4.2-21.8 years) were reviewed.

RESULTS

All tumors were located superficially in the frontal/temporal lobes and sharply delineated, displaying little mass effect. Near the circle of Willis, the tumors encompassed the arteries. All except one demonstrated characteristics of low-to-intermediate aggressiveness with high-to-intermediate T2WI and ADC signals and bone remodeling. Most tumors (n = 7) showed a homogeneous ground-glass aspect on T2-weighted and FLAIR images. On the basis of the original histopathologic diagnosis, 6 patients received postsurgical chemo-/radiotherapy, 2 were irradiated after surgery, and 1 patient underwent tumor resection only. At a median follow-up of 61 months (range, 10-154 months), 6 patients were alive in a first complete remission and 2 with stable disease 10 and 21 months after diagnosis. The only patient with progressive disease was lost to follow-up. Five-year overall and event-free survival was 100% and 86±13%, respectively.

CONCLUSIONS

This case series presents radiomorphologic characteristics highly predictive of DGONC that contrast with the typical aspects of the original histopathologic diagnoses. This presentation underlines the definition of DGONC as a separate entity, from a clinical perspective. Complete resection may be favorable for long-term disease control in patients with DGONC. The efficacy of nonsurgical treatment modalities should be evaluated in larger series.

P11.37.B When to resect or biopsy for patients with supratentorial glioblastoma: a multivariable prediction model

Background

The prospects of a patient with suspected glioblastoma may rely heavily on the indication for surgical resection versus biopsy only. Biopsy percentages vary considerably across hospitals and guidelines for treatment of glioblastoma lack criteria for surgical decision-making. To identify patient and tumor characteristics associated with the decision to resect or biopsy a glioblastoma and to develop and validate a prediction model for decision support.

Material and Methods

Clinical data and pre-operative MRI scans were collected for adults who underwent first-time surgery for supratentorial glioblastoma from a registry-based cohort study of 12 hospitals from the Netherlands, Germany, France, Italy, and the United States between 1st of January 2007 and 31st of December 2011. The main outcome was the type of surgical procedure: surgical resection or biopsy only. Predictors were patient- and tumor-related characteristics. Radiological factors were extracted from MRI using an automated tumor segmentation method. A prediction model was constructed using multivariable logistic regression analysis. The model was cross-validated and externally validated with a leave-one-hospital-out approach.

Results

Out of 1053 patients treated for glioblastoma, 28% underwent biopsy only. Biopsy rates varied from 15-40% across hospitals. The prediction model showed excellent discrimination with an average area under the curve of 0.86. Of the patient-related characteristics, younger age was associated more with resection and Karnofsky Performance Score of 60 or less with biopsy. Of the tumor-related characteristics, a location in the right hemisphere, unifocality, no tumor midline crossing, and no involvement of the cortical spinal tract, were associated with resection, as well as a high expected resectability index, a location in the right occipital lobe, and a higher percentage of tumor in Schaefer’s dorsal or ventral attention, limbic, and default networks. External validation proved acceptable to outstanding discrimination with areas under the curve ranging between 0.79 and 0.92 for hospitals.

Conclusion

A prediction model is presented and validated to support the decision to resect or to biopsy a patient with a suspected supratentorial glioblastoma. In this prediction model, tumor-related characteristics were more informative than patient-related factors. This may support surgical decision-making for individual patients, or facilitate comparisons of patient cohorts between surgeons or institutions.

KS01.4.A Transcriptional evolution of glioblastoma point towards changes in bulk composition, mesenchymal sub-type as end-state, and a prognostic association with increased extracellular matrix gene expression

Background

Glioblastoma is the most prevalent and severe type of malignant brain tumor in adults. Although the genetic make-up initiating glioblastoma is increasingly better understood, a better understanding in the mechanisms that drive its evolution, heterogeneity and therapy resistance may reveal new directions for therapy development. To get better insights into glioblastoma evolution, we analyzed and deconvoluted transcriptomes of primary and recurrent glioblastoma resections.

Material and Methods

Matching primary and secondary resections from n=185 uniformly treated glioblastoma patients were collected as part of EORTC Study 1542 and RNA-sequenced. Data was extended with pairs from n=51 patients from the GLASS study. The datasets were subjected to differential and deconvolution analysis using in-house algorithms.

Results

When projecting the tumor samples into a reduced Glioblastoma Intrinsic Transcriptional Subtype space, visualization of transitions indicated that the CL subtype switches most often. As we found no more transitions from MES to other subtypes than to be expected by chance, we concluded that MES is an end-state. On average, tumor purity percentages decreased from ~67% to ~50%, mostly due to an increase in macrophages/microglia. Differential expression analysis was performed with correction for the fraction of non-malignant cells. While expression of glioblastoma associated oncogenes did not change significantly over time, marker genes for macrophages/microglia, neurons and oligodendrocytes were up-regulated whereas endothelial cell markers were down-regulated. A cluster of ~30 extracellular matrix associated (ECM) genes increased significantly over time. Single cell RNA-seq, IF-staining and RNA-ish indicated the signature is most strongly expressed near intra-tumoral vessels. Since endothelial marker genes were down-regulated over time, this suggests a form of prognostic vessel progression with a representative transcriptome signature.

Conclusion

Using a large cohort and validation set of uniformly treated patients, we demonstrate how the glioblastoma transcriptome changes over time with in particular changes the composition of the tumor and its environment. The tumor purity decrease over times suggests a more invasive phenotype or recruitment of non-malignant cells or a combination of both. A post-progression increase in expression of ECM-associated genes expressed near blood vessels was associated with poor survival. Concluding, while no consistent path for transcriptional evolution of tumor cells was observed other than transitions to the MES subtype, glioblastoma becomes more aggressive in time by (re-)organizing its environment.

The Aftercare Survey: Assessment and intervention practices after brain tumor surgery in Europe

Background

People with gliomas need specialized neurosurgical, neuro-oncological, psycho-oncological, and neuropsychological care. The role of language and cognitive recovery and rehabilitation in patients' well-being and resumption of work is crucial, but there are no clear guidelines for the ideal timing and character of assessments and interventions. The goal of the present work was to describe representative (neuro)psychological practices implemented after brain surgery in Europe.

Methods

An online survey was addressed to professionals working with individuals after brain surgery. We inquired about the assessments and interventions and the involvement of caregivers. Additionally, we asked about recommendations for an ideal assessment and intervention plan.

Results

Thirty-eight European centers completed the survey. Thirty of them offered at least one postsurgical (neuro)psychological assessment, mainly for language and cognition, especially during the early recovery stage and at long term. Twenty-eight of the participating centers offered postsurgical therapies. Patients who stand the highest chances of being included in evaluation and therapy postsurgically are those who underwent awake brain surgery, harbored a low-grade glioma, or showed poor recovery. Nearly half of the respondents offer support programs to caregivers, and all teams recommend them. Treatments differed between those offered to individuals with low-grade glioma vs those with high-grade glioma. The figure of caregiver is not yet fully recognized in the recovery phase.

Conclusion

We stress the need for more complete rehabilitation plans, including the emotional and health-related aspects of recovery. In respondents' opinions, assessment and rehabilitation plans should also be individually tailored and goal-directed (eg, professional reinsertion).

Preoperative Brain Tumor Imaging: Models and Software for Segmentation and Standardized Reporting

For patients suffering from brain tumor, prognosis estimation and treatment decisions are made by a multidisciplinary team based on a set of preoperative MR scans. Currently, the lack of standardized and automatic methods for tumor detection and generation of clinical reports, incorporating a wide range of tumor characteristics, represents a major hurdle. In this study, we investigate the most occurring brain tumor types: glioblastomas, lower grade gliomas, meningiomas, and metastases, through four cohorts of up to 4,000 patients. Tumor segmentation models were trained using the AGU-Net architecture with different preprocessing steps and protocols. Segmentation performances were assessed in-depth using a wide-range of voxel and patient-wise metrics covering volume, distance, and probabilistic aspects. Finally, two software solutions have been developed, enabling an easy use of the trained models and standardized generation of clinical reports: Raidionics and Raidionics-Slicer. Segmentation performances were quite homogeneous across the four different brain tumor types, with an average true positive Dice ranging between 80 and 90%, patient-wise recall between 88 and 98%, and patient-wise precision around 95%. In conjunction to Dice, the identified most relevant other metrics were the relative absolute volume difference, the variation of information, and the Hausdorff, Mahalanobis, and object average symmetric surface distances. With our Raidionics software, running on a desktop computer with CPU support, tumor segmentation can be performed in 16–54 s depending on the dimensions of the MRI volume. For the generation of a standardized clinical report, including the tumor segmentation and features computation, 5–15 min are necessary. All trained models have been made open-access together with the source code for both software solutions and validation metrics computation. In the future, a method to convert results from a set of metrics into a final single score would be highly desirable for easier ranking across trained models. In addition, an automatic classification of the brain tumor type would be necessary to replace manual user input. Finally, the inclusion of post-operative segmentation in both software solutions will be key for generating complete post-operative standardized clinical reports.

Abstract 6140: Transcriptional evolution of glioblastoma reveals changes in bulk composition, mesenchymal sub-type as end-state, and a prognostic association with increased extracellular matrix gene expression

Background: Glioblastoma is the most prevalent and severe type of malignant brain tumor in adults. Although the genetic make-up initiating glioblastoma is increasingly better understood, a better understanding in the mechanisms that drive its evolution, heterogeneity and therapy resistance may reveal new directions for therapy development. To get better insights into glioblastoma evolution, we analyzed and de-convoluted transcriptomes of primary and recurrent glioblastoma resections.

Material and Methods: Matching primary and secondary resections from n=185 glioblastoma patients were collected as part of EORTC Study 1542. The study was extended with tumor pairs from n=51 patients from the international GLASS study. The datasets were subjected to differential and deconvolution analysis using in-house algorithms.

Results: When mapping the tumor samples into a reduced Glioblastoma Intrinsic Transcriptional Subtype space, we visualized subtype traversal, indicating that the CL subtype most often switches. As we found no more transitions from MES to other subtypes than to be expected by chance, we concluded that MES is an end-state. On average, tumor cell percentages decreased from ~67% to ~50% mostly due to an increase in TAM/microglia. Differential expression analysis was performed with correction for tumor cell percentages. While expression of most known oncogenes did not change considerably over time, marker genes of TAM/microglia, neurons and oligodendrocytes were up-regulated whereas endothelial cell markers were down-regulated over time. Furthermore, a cluster of ~30 extracellular matrix-associated genes increase significantly over time. A signature representing the gene-set was significantly associated with poor survival; high signatures were in particular associated to survival in secondary resections (P = 6.613e-06, Kaplan-Meier estimator). This suggests that the increase of extracellular matrix expression fulfils an important role in glioblastoma evolution.

Conclusion: Using a large cohort, we interrogated changes in the glioblastoma transcriptome over time and found that in particular the composition of the tumor and its environment changes. The tumor cell percentage drops, suggesting more invasion or recruitment of non-malignant cells or a combination of both. This change is independent of an increase in the prognostic increase in extracellular matrix expression.

Citation Format: Youri Hoogstrate, Kaspar Draaisma, Santoesha A. Ghisai, Iris de Heer, Levi van Hijfte, Wouter Coppieters, Melissa Kerkhof, Astrid Weyerbrock, Marc Sanson, Ann Hoeben, Slávka Lukacova, Giuseppe Lombardi, Sieger Leenstra, Monique Hanse, Ruth Fleischeuer, Colin Watts, Joseph McAbee, Nicos Angelopoulos, Thierry Gorlia, Vassilis Golfinopoulos, Johan M. Kros, Vincent Bours, Martin J. van den Bent, Pierre A. Robe, Pim J. French. Transcriptional evolution of glioblastoma reveals changes in bulk composition, mesenchymal sub-type as end-state, and a prognostic association with increased extracellular matrix gene expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6140.

Conventional MRI Criteria to Differentiate Progressive Disease from Treatment-Induced Effects in High-Grade (WHO Grade 3-4) Gliomas

BACKGROUND

Post-treatment radiological deterioration of patients with an irradiated high-grade (WHO grade 3-4) glioma (HGG) may be the result of true progressive disease (PD) or treatment-induced effects (TIE). Differentiation between these entities is of great importance, but remains a diagnostic challenge. This study assesses the diagnostic value of conventional MRI characteristics to differentiate PD from TIE in HGGs.

MATERIAL AND METHODS

In this single-centre, retrospective, consecutive cohort study, we included adults with a HGG, who were treated with (chemo-)radiotherapy and subsequently developed a new or increasing contrast-enhancing lesion on conventional follow-up MRI. TIE and PD were defined radiologically as stable/decreased for ≥6 weeks or RANO-progression, and histologically as TIE without viable tumour or PD. Two neuroradiologists assessed twenty-one preselected MRI characteristics of the progressive lesions. The statistical analysis included logistic regression to develop a) a full multivariable model b) a diagnostic model with model reduction, and a Cohen's Kappa interrater reliability (IRR) coefficient.

RESULTS

210 patients (median age=61, IQR=54-68, 189 males) with 284 lesions were included, of which 141 (50%) had PD. Median time to PD was 2 (0.7-6.1) and to TIE 0.9 (0.7-3.5) months after radiotherapy. After multivariable modelling and model reduction, the following determinants prevailed: Radiation dose (Odds ratio (OR)=0.68, 95%-CI=0.49-0.93), longer time to progression (TTP, OR=3.56, 95%-CI=1.84-6.88), marginal enhancement (OR=2.04, 95%-CI=1.09-3.83), soap bubble enhancement (OR=2.63, 95%-CI=1.39-4.98) and isointense apparent diffusion coefficient (ADC)-signal (OR=2.11, 95%-CI=1.05-4.24). ORs>1 indicate higher odds of PD. The Hosmer&Lemeshow test showed good calibration (p=0.947) and the area under the ROC-curve was 0.722 (95%-CI=0.66-0.78). In the glioblastoma subgroup, TTP, marginal enhancement and ADC-signal were significant. IRR analysis between neuroradiologists revealed moderate to near-perfect agreement for the predictive items, but poor agreement for others.

DISCUSSION

Several characteristics from conventional MRI are significant predictors for the discrimination between PD and TIE. However, IRR was variable. Conventional MRI characteristics from this study should be incorporated into a multimodal diagnostic model with advanced imaging techniques.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in patients with irradiated HGGs, radiation dose, longer time to progression, marginal enhancement, soap bubble enhancement and isointense apparent ADC-signal distinguish PD from TIE.

Complications, compliance and undertreatment do not explain the relationship between cognition and survival in diffuse glioma patients

Background

Cognitive deficits occur in all different grades of glioma. In a recent study, we found these deficits to be independently, and possibly causally, related to survival in diffuse gliomas. In this study, we investigated whether the relationship between cognition and survival was mediated by three different factors: undertreatment, complications of treatment, and compliance. We hypothesized that patients with cognitive impairment may undergo less intensive treatment, be less compliant, and suffer more from complications, resulting in shortened survival for cognitively impaired patients.

Methods

In a retrospective cohort study of patients undergoing awake craniotomy between operative neuropsychological assessments in five cognitive domains. We used Structural Equation Modeling to perform mediation analyses. Mediation analyses are analyses to evaluate whether a variable is a factor in the causal chain, referred to as an intermediate factor.

Results

In total 254 patients were included, of whom 111 patients were LGG patients and 143 were HGG patients. The most frequently impaired domain was memory (37.8% ≤–2 SD) in HGG and attention and executive functioning in LGG (33.3≤–1.5 SD). We confirmed the significant association between different cognitive domains and survival. These associations could not be explained by one of the aforementioned intermediate factors.

Conclusions

This suggests that other mechanisms should be involved in the relation between cognition and survival. Hypothetically, cognitive functioning can act as a marker for diffuse infiltration of the tumor or cognitive functioning and survival could be determined by overlapping germline and somatic tumoral molecular-genetic factors.

Early Surgery Prolongs Professional Activity in IDH Mutant Low-Grade Glioma Patients: A Policy Change Analysis

Background

Until 2015, Dutch guidelines recommended follow-up and biopsy rather than surgery as initial care for suspected low-grade gliomas (LGG). Given evidence that surgery could extend patient survival, our center stopped following this guideline on January 1, 2010 and opted for early maximal safe resection of LGG. The effects of early surgery on the ability of patients to work remains little documented.

Methods

A total of 104 patients operated on at our center between January 2000 and April 2013 and diagnosed with the WHO 2016 grade 2 astrocytoma, IDH mutant or oligodendroglioma, IDH mutant and deleted 1p19q were included. The clinical characteristics, survival, and work history of patients operated on before or after January 2010 were obtained from the patients' records and compared. The minimal follow-up was 8 years.

Results

As per policy change, the interval between radiological diagnosis and first surgery decreased significantly after 2010. Likewise, before 2010, 25.8% of tumors were initially biopsied, 51.6% were resected under anesthesia, and 22.5% under awake conditions versus 14.3%, 23.8%, and 61.9% after this date (p < 0.001). The severity of permanent postoperative neurological deficits decreased after 2010. In total, 82.5% of the patients returned to work postoperatively before 2010 versus 100% after 2010. The postoperative control of epilepsy increased significantly after 2010 (74.4% vs. 47.9%). The median time from diagnosis to a definitive incapacity to work increased by more than 2 years after 2010 (88.7 vs. 62.2 months).

Conclusion

A policy shift towards early aggressive surgical treatment of IDH mutant LGG is safe and prolongs the patients' ability to work.

Prognostic significance of DNA methylation profiles at MRI enhancing tumor recurrence: a report from the EORTC 26091 TAVAREC trial

PURPOSE

Despite recent advances in the molecular characterization of gliomas, it remains unclear which patients benefit most from which second line treatments. The TAVAREC trial was a randomized, open-label phase 2 trial assessing the benefit of the addition of the angiogenesis inhibitor bevacizumab to treatment with temozolomide in patients with a first enhancing recurrence of WHO grade 2 or 3 glioma without 1p/19q codeletion. We evaluated the prognostic significance of genome wide DNA methylation profiles and copy number variations on the TAVAREC trial samples.

EXPERIMENTAL DESIGN

IDH-mutation status was determined via Sanger sequencing and immunohistochemistry. DNA methylation analysis was performed using the MethylationEPIC BeadChip (Illumina) from which 1p/19q codeletion, MGMT promoter methylation (MGMT-STP27) and homozygous deletion of CDKN2A/B were determined. DNA-methylation classes were determined according to classifiers developed in Heidelberg and TCGA ("Heidelberg" and "TCGA" classifier respectively).

RESULTS

DNA methylation profiles of 122 samples were successfully determined. As expected, most samples were IDH-mutant (89/122) and MGMT promotor methylated (89/122). Methylation classes were prognostic for time to progression. However, Heidelberg methylation classes determined at time of diagnosis were no longer prognostic following enhancing recurrence of the tumor. In contrast, TCGA methylation classes of primary samples remained prognostic also following enhancing recurrence. Homozygous deletions in CDKN2A/B were found in 10/87 IDH-mutated samples and were prognostically unfavorable at recurrence.

CONCLUSIONS

DNA methylome Heidelberg classification at time of diagnosis is no longer of prognostic value at the time of enhancing recurrence. CDKN2A/B deletion status was predictive of survival from progression of IDH-mutated tumors.

Between-hospital variation in time to glioblastoma surgery: a report from the Quality Registry Neuro Surgery in the Netherlands

OBJECTIVE

Patients with glioblastoma are often scheduled for urgent elective surgery. Currently, the impact of the waiting period until glioblastoma surgery is undetermined. In this national quality registry study, the authors determined the wait times until surgery for patients with glioblastoma, the risk factors associated with wait times, and the risk-standardized variation in time to surgery between Dutch hospitals. The associations between time to surgery and patient outcomes were also explored.

METHODS

Data from all 4589 patients who underwent first-time glioblastoma surgery between 2014 and 2019 in the Netherlands were collected by 13 hospitals in the Quality Registry Neuro Surgery. Time to surgery comprised 1) the time from first MR scan to surgery (MTS), and 2) the time from first neurosurgical consultation to surgery (CTS). Long MTS was defined as more than 21 days and long CTS as more than 14 days. Potential risk factors were analyzed in multivariable logistic regression models. The standardized rate of long time to surgery was analyzed using funnel plots. Patient outcomes including Karnofsky Performance Scale (KPS) score change, complications, and survival were analyzed by multivariable logistic regression and proportional hazards models.

RESULTS

The median overall MTS and CTS were 18 and 9 days, respectively. Overall, 2576 patients (56%) had an MTS within 3 weeks and 3069 (67%) had a CTS within 2 weeks. Long MTS was significantly associated with older age, higher preoperative KPS score, higher American Society of Anesthesiologists comorbidity class, season, lower hospital case volume, university affiliation, and resection. Long CTS was significantly associated with higher baseline KPS score, university affiliation, resection, more recent year of treatment, and season. In funnel plots, considerable practice variation was observed between hospitals in patients with long times to surgery. Fewer patients with KPS score improvement were observed after a long time until resection. Long CTS was associated with longer survival. Complications and KPS score decline were not associated with time to surgery.

CONCLUSIONS

Considerable between-hospital variation among Dutch hospitals was observed in the time to glioblastoma surgery. A long time to resection impeded KPS score improvement, and therefore, patients who may improve should be identified for more urgent resection. Longer survival was observed in patients selected for longer time until surgery after neurosurgical consultation (CTS).

Tumor-related molecular determinants of neurocognitive deficits in patients with diffuse glioma

BACKGROUND

Cognitive impairment is a common and debilitating symptom in patients with diffuse glioma, and is the result of multiple factors. We hypothesized that molecular tumor characteristics influence neurocognitive functioning (NCF), and aimed to identify tumor-related markers of NCF in diffuse glioma patients.

METHODS

We examined the relation between cognitive performance (executive function, memory, and psychomotor speed) and intratumoral expression levels of molecular markers in treatment-naive patients with diffuse glioma. We performed a single-center study in a consecutive cohort, through a two-step design: (1) hypothesis-free differential expression and gene set enrichment analysis to identify candidate oncogenetic markers for cognitive impairment. Nineteen molecular markers of interest were derived from this set of genes, as well as from prior knowledge; (2) correlation of cognitive performance to intratumoral expression levels of these nineteen molecular markers, measured with immunohistochemistry.

RESULTS

From 708 included patients with immunohistochemical data, we performed an in-depth analysis of neuropsychological data in 197, and differential expression analysis in 65 patients. After correcting for tumor volume and location, we found significant associations between expression levels of CD3 and IDH-1 and psychomotor speed; between IDH-1, ATRX, NLGN3, BDNF, CK2Beta, EAAT1, GAT-3, SRF, and memory performance; and between IDH-1, P-STAT5b, NLGN3, CK2Beta, and executive functioning. P-STAT5b, CD163, CD3, and Semaphorin-3A were independently associated after further correction for histopathological grade.

CONCLUSION

Molecular characteristics of glioma can be independent determinants of patients' cognitive functioning. This suggests that besides tumor volume, location, and histological grade, variations in glioma biology influence cognitive performance through mechanisms that include perturbation of neuronal communication. These results pave the way towards targeted cognition improving therapies in neuro-oncology.

Landscape of driver gene events, biomarkers, and druggable targets identified by whole-genome sequencing of glioblastomas

BACKGROUND

The survival of glioblastoma patients is poor. Median survival after diagnosis is 15 months, despite treatment involving surgical resection, radiotherapy, and/or temozolomide chemotherapy. Identification of novel targets and stratification strategies of glioblastoma patients to improve patient survival is urgently needed. Whole-genome sequencing (WGS) is the most comprehensive means to identify such DNA-level targets. We report a unique set of WGS samples along with comprehensive analyses of the glioblastoma genome and potential clinical impact of WGS.

METHODS

Our cohort consisted of 42 glioblastoma tumor tissue and matched whole-blood samples, which were whole-genome sequenced as part of the CPCT-02 study. Somatic single-nucleotide variants, small insertions/deletions, multi-nucleotide variants, copy-number alterations (CNAs), and structural variants were analyzed. These aberrations were harnessed to investigate driver genes, enrichments in CNAs, mutational signatures, fusion genes, and potential targeted therapies.

RESULTS

Tumor mutational burden (TMB) was similar to other WGS efforts (1-342 mutations per megabase pair). Mutational analysis in low TMB samples showed that the age-related CpG demethylation signature was dominant, while hyper- and ultramutated tumors had additional defective DNA mismatch repair signatures and showed microsatellite instability in their genomes. We detected chromothripsis in 24% of our cohort, recurrently on chromosomes 1 and 12. Recurrent noncoding regions only resulted in TERT promoter variants. Finally, we found biomarkers and potentially druggable changes in all but one of our tumor samples.

CONCLUSIONS

With high-quality WGS data and comprehensive methods, we identified the landscape of driver gene events and druggable targets in glioblastoma patients.

Added Value of Cognition in the Prediction of Survival in Low and High Grade Glioma

Background: Diffuse gliomas, which are at WHO grade II-IV, are progressive primary brain tumors with great variability in prognosis. Our aim was to investigate whether pre-operative cognitive functioning is of added value in survival prediction in these patients.

Methods: In a retrospective cohort study of patients undergoing awake craniotomy between 2010 and 2019 we performed pre-operative neuropsychological assessments in five cognitive domains. Their added prognostic value on top of known prognostic factors was assessed in two patient groups [low- (LGG) and high-grade gliomas (HGG]). We compared Cox proportional hazards regression models with and without the cognitive domain by means of loglikelihood ratios tests (LRT), discriminative performance measures (by AUC), and risk classification [by Integrated Discrimination Index (IDI)].

Results: We included 109 LGG and 145 HGG patients with a median survival time of 1,490 and 511 days, respectively. The domain memory had a significant added prognostic value in HGG as indicated by an LRT (p-value = 0.018). The cumulative AUC for HGG with memory included was.78 (SD = 0.017) and without cognition 0.77 (SD = 0.018), IDI was 0.043 (0.000–0.102). In LGG none of the cognitive domains added prognostic value.

Conclusions: Our findings indicated that memory deficits, which were revealed with the neuropsychological examination, were of additional prognostic value in HGG to other well-known predictors of survival.

The EGFRvIII transcriptome in glioblastoma, a meta-omics analysis

Background

EGFR is among the genes most frequently altered in glioblastoma, with exons 2-7 deletions (EGFRvIII) being among its most common genomic mutations. There are conflicting reports about its prognostic role and it remains unclear whether and how it differs in signaling compared with wildtype EGFR.

Methods

To better understand the oncogenic role of EGFRvIII, we leveraged 4 large datasets into 1 large glioblastoma transcriptome dataset (n = 741) alongside 81 whole-genome samples from 2 datasets.

Results

The EGFRvIII/EGFR expression ratios differ strongly between tumors and range from 1% to 95%. Interestingly, the slope of relative EGFRvIII expression is near-linear, which argues against a more positive selection pressure than EGFR wildtype. An absence of selection pressure is also suggested by the similar survival between EGFRvIII-positive and -negative glioblastoma patients. EGFRvIII levels are inversely correlated with pan-EGFR (all wildtype and mutant variants) expression, which indicates that EGFRvIII has a higher potency in downstream pathway activation. EGFRvIII-positive glioblastomas have a lower CDK4 or MDM2 amplification incidence than EGFRvIII-negative (P = .007), which may point toward crosstalk between these pathways. EGFRvIII-expressing tumors have an upregulation of “classical” subtype genes compared to those with EGFR-amplification only (P = 3.873e⁻⁶). Genomic breakpoints of the EGFRvIII deletions have a preference toward the 3′-end of the large intron-1. These preferred breakpoints preserve a cryptic exon resulting in a novel EGFRvIII variant and preserve an intronic enhancer.

Conclusions

These data provide deeper insights into the complex EGFRvIII biology and provide new insights for targeting EGFRvIII mutated tumors.

Glioblastoma Surgery Imaging-Reporting and Data System: Validation and Performance of the Automated Segmentation Task

For patients with presumed glioblastoma, essential tumor characteristics are determined from preoperative MR images to optimize the treatment strategy. This procedure is time-consuming and subjective, if performed by crude eyeballing or manually. The standardized GSI-RADS aims to provide neurosurgeons with automatic tumor segmentations to extract tumor features rapidly and objectively. In this study, we improved automatic tumor segmentation and compared the agreement with manual raters, describe the technical details of the different components of GSI-RADS, and determined their speed. Two recent neural network architectures were considered for the segmentation task: nnU-Net and AGU-Net. Two preprocessing schemes were introduced to investigate the tradeoff between performance and processing speed. A summarized description of the tumor feature extraction and standardized reporting process is included. The trained architectures for automatic segmentation and the code for computing the standardized report are distributed as open-source and as open-access software. Validation studies were performed on a dataset of 1594 gadolinium-enhanced T1-weighted MRI volumes from 13 hospitals and 293 T1-weighted MRI volumes from the BraTS challenge. The glioblastoma tumor core segmentation reached a Dice score slightly below 90%, a patientwise F1-score close to 99%, and a 95th percentile Hausdorff distance slightly below 4.0 mm on average with either architecture and the heavy preprocessing scheme. A patient MRI volume can be segmented in less than one minute, and a standardized report can be generated in up to five minutes. The proposed GSI-RADS software showed robust performance on a large collection of MRI volumes from various hospitals and generated results within a reasonable runtime.

P14.17 Conventional MRI criteria differentiate true tumour progression from treatment-induced effects in irradiated WHO grade 3 and 4 gliomas

BACKGROUND

Post-treatment radiological deterioration of patients with an irradiated high-grade (WHO grade 3 and 4) glioma (HGG) may be the result of true progressive disease (PD) or treatment-induced effects (TIE). Differentiation between these two entities is of great importance, but remains a diagnostic challenge. This study assesses the diagnostic value of conventional MRI characteristics to differentiate PD from TIE in treated HGGs.

MATERIAL AND METHODS

In this single-centre, retrospective cohort study, we included adult patients with a HGG, who were treated with radiotherapy and subsequently developed a new or increasing contrast-enhancing lesion on conventional follow-up MRI. TIE and PD were defined radiologically as stable/decreased for a minimum of six weeks or progressive according to the RANO criteria, and histologically as predominantly TIE without viable tumour or PD. Demographic and clinical data were retrieved. Twenty-one preselected MRI characteristics of the progressive lesions were assessed by two neuroradiologists. The statistical analysis included logistic regression to develop a) a full multivariable model b) a diagnostic model with model reduction, and a Cohen’s Kappa interrater reliability coefficient.

RESULTS

210 patients (median age 61, IQR=54–68, 189 males) with 284 lesions were included, of which 141 (50%) had PD. Median time to PD was 2 (0.7–6.1) and to TIE 0.9 (0.7–3.5) months after RT. In multivariable modelling and after model reduction, the following determinants were significant diagnostic factors: Radiation dose (Odds ratio (OR)=0.68, p=0.017), longer time since radiotherapy (OR=3.56, p&lt;0.0005), certain enhancement patterns (soap bubble enhancement: OR=2.63, p=0.003), isointense apparent diffusion coefficient-signal (OR=2.11, p=0.036), development of multiple new lesions (OR=1.68, p=0.088) and increased marginal enhancement (OR=2.04, p=0.027). ORs of &gt;1 indicate higher odds of PD. The Hosmer & Lemeshow test showed a good calibration (p=0.947) and the area under the ROC-curve was 0.722 (95%-CI=0.66–0.78). Interrater reliability analysis between neuroradiologists revealed moderate to near-perfect agreement for the significantly predictive items, but poor agreement for others.

CONCLUSION

In patients with irradiated high-grade gliomas, several characteristics from conventional MRI are significant predictors for the discrimination between true progression and treatment-induced effects. Interrater reliability for these characteristics was variable. Conventional MRI characteristics from this study should be incorporated into a multimodal diagnostic model that includes advanced imaging techniques.

FUNDING INFORMATION

Foundation Vrienden UMC Utrecht and The StophersenkankerNU Foundation.

P14.23 Relation between neurological deficits and location of postsurgical ischemia in glioma resection

BACKGROUND

Postoperative ischemia is a known complications of glioma resection and can lead to neurological deficits. New or worsened postoperative deficits are often transient, but some patients experience persisting effects after surgery. Neuroanatomical location of ischemia is suspected to play an important role in the development as well as persistence of neurological deficits. Therefore, the aim of this study was to investigate the spatial relation between postoperative ischemia and short-term and long-term neurological deficits.

MATERIAL AND METHODS

Postoperative ischemia was defined as new confluent areas of diffusion restriction on DWI in a retrospective database of 144 adult WHO grade II-IV supratentorial glioma patients, who received MRI within 3 days after resection in 2012–2014. New or worsened neurological deficits of any grade at discharge and after 3 months was assessed in relation to postoperative ischemia by an experienced neuro-oncologist. We manually delineated ischemic lesions and spatially normalized these to stereotaxic MNI space. Next, we performed voxel-based analysis (VBA) to identify locations of ischemia associated with new or worsened neurological deficits and corrected for multiple comparisons using family-wise error correction to eliminate false positive results. Delineations were labeled using the Harvard-Oxford cortical and subcortical atlases and a white matter atlas (XTRACT).

RESULTS

Any new or worsened neurological deficits were present in 44 (30.5%) cases at discharge and in 27 (20.9%) cases after 3 months, of which respectively 26 (18%) and 21 (16.3%) were related to ischemia. Volume of ischemia was significantly associated with deficits at discharge (P = 0.003) and after 3 months (P = 0.039). No areas of ischemia were associated with a lack of new or worsened deficits. A statistically significant cluster of 42.96cc was associated with deficits at discharge and encompassed the right frontal, insular and tempo-occipital regions. Voxels associated only with deficits at discharge included lateral occipital cortices and supramarginal gyri. A cluster of 17.68cc in the right frontal and insular lobes was significantly associated with deficits after 3 months. Overlapping areas included the right thalamus, caudate nucleus, putamen, globus pallidum, insular cortex, middle and inferior temporal gyri, corticospinal tract and superior thalamic radiation.

CONCLUSION

Transient and persisting new or worsened deficits after glioma resection were significantly associated with volume of postoperative ischemia. Ischemic lesions in right frontal and insular regions, including the basal nuclei, corticospinal tract and superior thalamic radiation were significantly associated with persisting neurological deficits after 3 months, while temporo-occipital lesions were associated with transient deficits only found at discharge.

P14.30 Voxelwise analysis of spatial distribution of postoperative ischemia in diffuse glioma

BACKGROUND

Surgical treatment of diffuse glioma is performed to reduce tumor mass effect and to pave the way for adjuvant (chemo)radiotherapy. As a complication of surgery, ischemic lesions are often found in the postoperative setting. Not only can these lesion induce neurological deficits, but their volume has also been associated with reduced survival time. Prior studies suggest areas with a singular vascular supply to be more prone to postoperative ischemic lesions, although the precise cause is yet unknown. The aim of this study was to explore the volumetric and spatial distributions of postoperative ischemic lesions and their relation to arterial territories in glioma patients.

MATERIAL AND METHODS

We accessed a retrospective database of 144 adult cases with WHO grade II-IV supratentorial gliomas, who received surgery and postoperative MRI within 3 days in 2012–2014. We identified 93 patients with postoperative ischemia, defined as new confluent diffusion restriction on DWI. Ischemic lesions were manually delineated and spatially normalized to stereotaxic MNI space. Voxel-based analysis (VBA) was performed to compare presence and absence of postoperative ischemia. False positive results were eliminated by family-wise error correction. Areas of ischemia were labeled using an arterial territory map, the Harvard-Oxford cortical and subcortical atlases and the XTRACT white matter atlas.

RESULTS

Median volume of confluent ischemia was 3.52cc (IQR 2.15–5.94). 23 cases had only ischemic lesion in the left hemisphere, 46 in the right hemisphere and 24 bilateral. Median volume was 3.08cc (IQR 1.35–5.72) in left-sided lesions and 2.47cc (1.01–4.24) in right-sided lesions. Volume of ischemic lesions was not associated with survival after 1, 2 or 5 years. A cluster of 125.18cc was found to be significantly associated with development of postoperative ischemia. 73% of this cluster was situated in the arterial territory of the right middle cerebral artery (MCA), limited by the border of the posterior cerebral artery (PCA), and the watershed area between the right MCA and the right anterior cerebral artery (ACA). Significant areas were located in the frontal lobes, spanning into the right temporo-occipital region, and predominantly included right and left thalamus, caudate nucleus, putamen, pallidum, as well as right temporal gyri and insular cortex, and parts of the right corticospinal tract, longitudinal fasciculi and superior thalamic radiation.

CONCLUSION

We found slightly more and larger ischemic lesions in the right than left hemisphere after glioma resection. A statistically significant cluster of voxels of postoperative ischemia was found in the territory of the right MCA and watershed area of the right ACA. Exploration of the spatial distribution of these lesions could help elucidate their etiology and form the basis for predicting clinically relevant postoperative ischemia.

On the cutting edge of glioblastoma surgery: where neurosurgeons agree and disagree on surgical decisions

OBJECTIVE

The aim of glioblastoma surgery is to maximize the extent of resection while preserving functional integrity. Standards are lacking for surgical decision-making, and previous studies indicate treatment variations. These shortcomings reflect the need to evaluate larger populations from different care teams. In this study, the authors used probability maps to quantify and compare surgical decision-making throughout the brain by 12 neurosurgical teams for patients with glioblastoma.

METHODS

The study included all adult patients who underwent first-time glioblastoma surgery in 2012-2013 and were treated by 1 of the 12 participating neurosurgical teams. Voxel-wise probability maps of tumor location, biopsy, and resection were constructed for each team to identify and compare patient treatment variations. Brain regions with different biopsy and resection results between teams were identified and analyzed for patient functional outcome and survival.

RESULTS

The study cohort consisted of 1087 patients, of whom 363 underwent a biopsy and 724 a resection. Biopsy and resection decisions were generally comparable between teams, providing benchmarks for probability maps of resections and biopsies for glioblastoma. Differences in biopsy rates were identified for the right superior frontal gyrus and indicated variation in biopsy decisions. Differences in resection rates were identified for the left superior parietal lobule, indicating variations in resection decisions.

CONCLUSIONS

Probability maps of glioblastoma surgery enabled capture of clinical practice decisions and indicated that teams generally agreed on which region to biopsy or to resect. However, treatment variations reflecting clinical dilemmas were observed and pinpointed by using the probability maps, which could therefore be useful for quality-of-care discussions between surgical teams for patients with glioblastoma.

Impaired Set-Shifting from Dorsal Stream Disconnection: Insights from a European Series of Right Parietal Lower-Grade Glioma Resection

Simple Summary

Awake surgery with cognitive monitoring has increasingly been implemented to preserve brain networks and functionality. More recently, not only surgery in the left but also in the right hemisphere, i.c., the parietal lobe, was associated with potential risk for deficits in cognitive functions, such as cognitive flexibility. We describe an explorative pilot study in an international consortium within clinical care as usual. Careful interpretation of our findings indicates that disconnection of the lateral part of the dorsal stream correlated with impaired set-shifting. More importantly, it illustrates the need for international collaboration on neuropsychological tests and methodologies to improve our understanding of white matter networks at risk during awake surgery.

Abstract

Awake surgery with cognitive monitoring has increasingly been implemented to preserve brain networks and functionality. More recently, not only surgery in the left but also in the right hemisphere, i.c., the parietal lobe, was associated with potential risk for deficits in cognitive functions, such as cognitive flexibility. In this explorative pilot study, we compare cognitive performance more than three months after surgery with baseline measurements and explore the association between cognitive decline and subcortical tracts that may have been severed during surgery in the right hemisphere. Twenty-two patients who underwent surgery for a right parietal low-grade glioma were assessed pre- and postoperatively using the Trail Making Test and the Stroop task to administer set-shifting abilities and inhibition. Volume measurements and lesion–symptom mapping analyses were performed on postoperative MRI scans. Careful interpretation of the results shows a change in TMT performance and not on the Stroop Task when the lateral part of the arcuate fasciculus is damaged, indicating that disconnection of the lateral part of the dorsal stream might be correlated specifically with impaired set-shifting and not with inhibition. More importantly, this study underlines the need for international concertation to allow larger studies to increase power and perform more detailed analyses.

Glioblastoma Surgery Imaging-Reporting and Data System: Standardized Reporting of Tumor Volume, Location, and Resectability Based on Automated Segmentations

Treatment decisions for patients with presumed glioblastoma are based on tumor characteristics available from a preoperative MR scan. Tumor characteristics, including volume, location, and resectability, are often estimated or manually delineated. This process is time consuming and subjective. Hence, comparison across cohorts, trials, or registries are subject to assessment bias. In this study, we propose a standardized Glioblastoma Surgery Imaging Reporting and Data System (GSI-RADS) based on an automated method of tumor segmentation that provides standard reports on tumor features that are potentially relevant for glioblastoma surgery. As clinical validation, we determine the agreement in extracted tumor features between the automated method and the current standard of manual segmentations from routine clinical MR scans before treatment. In an observational consecutive cohort of 1596 adult patients with a first time surgery of a glioblastoma from 13 institutions, we segmented gadolinium-enhanced tumor parts both by a human rater and by an automated algorithm. Tumor features were extracted from segmentations of both methods and compared to assess differences, concordance, and equivalence. The laterality, contralateral infiltration, and the laterality indices were in excellent agreement. The native and normalized tumor volumes had excellent agreement, consistency, and equivalence. Multifocality, but not the number of foci, had good agreement and equivalence. The location profiles of cortical and subcortical structures were in excellent agreement. The expected residual tumor volumes and resectability indices had excellent agreement, consistency, and equivalence. Tumor probability maps were in good agreement. In conclusion, automated segmentations are in excellent agreement with manual segmentations and practically equivalent regarding tumor features that are potentially relevant for neurosurgical purposes. Standard GSI-RADS reports can be generated by open access software.

CXCR4 expression in glioblastoma tissue and the potential for PET imaging and treatment with [68Ga]Ga-Pentixafor /[177Lu]Lu-Pentixather

Purpose

CXCR4 (over)expression is found in multiple human cancer types, while expression is low or absent in healthy tissue. In glioblastoma it is associated with a poor prognosis and more extensive infiltrative phenotype. CXCR4 can be targeted by the diagnostic PET agent [⁶⁸Ga]Ga-Pentixafor and its therapeutic counterpart [¹⁷⁷Lu]Lu-Pentixather. We aimed to investigate the expression of CXCR4 in glioblastoma tissue to further examine the potential of these PET agents.

Methods

CXCR4 mRNA expression was examined using the R2 genomics platform. Glioblastoma tissue cores were stained for CXCR4. CXCR4 staining in tumor cells was scored. Stained tissue components (cytoplasm and/or nuclei of the tumor cells and blood vessels) were documented. Clinical characteristics and information on IDH and MGMT promoter methylation status were collected. Seven pilot patients with recurrent glioblastoma underwent [⁶⁸Ga]Ga-Pentixafor PET; residual resected tissue was stained for CXCR4.

Results

Two large mRNA datasets (N = 284; N = 540) were assesed. Of the 191 glioblastomas, 426 cores were analyzed using immunohistochemistry. Seventy-eight cores (23 tumors) were CXCR4 negative, while 18 cores (5 tumors) had both strong and extensive staining. The remaining 330 cores (163 tumors) showed a large inter- and intra-tumor variation for CXCR4 expression; also seen in the resected tissue of the seven pilot patients—not directly translatable to [⁶⁸Ga]Ga-Pentixafor PET results. Both mRNA and immunohistochemical analysis showed CXCR4 negative normal brain tissue and no significant correlation between CXCR4 expression and IDH or MGMT status or survival.

Conclusion

Using immunohistochemistry, high CXCR4 expression was found in a subset of glioblastomas as well as a large inter- and intra-tumor variation. Caution should be exercised in directly translating ex vivo CXCR4 expression to PET agent uptake. However, when high CXCR4 expression can be identified with [⁶⁸Ga]Ga-Pentixafor, these patients might be good candidates for targeted radionuclide therapy with [¹⁷⁷Lu]Lu-Pentixather in the future.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05196-4.

Between-hospital variation in rates of complications and decline of patient performance after glioblastoma surgery in the dutch Quality Registry Neuro Surgery

Introduction

For decisions on glioblastoma surgery, the risk of complications and decline in performance is decisive. In this study, we determine the rate of complications and performance decline after resections and biopsies in a national quality registry, their risk factors and the risk-standardized variation between institutions.

Methods

Data from all 3288 adults with first-time glioblastoma surgery at 13 hospitals were obtained from a prospective population-based Quality Registry Neuro Surgery in the Netherlands between 2013 and 2017. Patients were stratified by biopsies and resections. Complications were categorized as Clavien-Dindo grades II and higher. Performance decline was considered a deterioration of more than 10 Karnofsky points at 6 weeks. Risk factors were evaluated in multivariable logistic regression analysis. Patient-specific expected and observed complications and performance declines were summarized for institutions and analyzed in funnel plots.

Results

For 2271 resections, the overall complication rate was 20 % and 16 % declined in performance. For 1017 biopsies, the overall complication rate was 11 % and 30 % declined in performance. Patient-related characteristics were significant risk factors for complications and performance decline, i.e. higher age, lower baseline Karnofsky, higher ASA classification, and the surgical procedure. Hospital characteristics, i.e. case volume, university affiliation and biopsy percentage, were not. In three institutes the observed complication rate was significantly less than expected. In one institute significantly more performance declines were observed than expected, and in one institute significantly less.

Conclusions

Patient characteristics, but not case volume, were risk factors for complications and performance decline after glioblastoma surgery. After risk-standardization, hospitals varied in complications and performance declines.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11060-021-03697-8.

Cognitive impairments are independently associated with shorter survival in diffuse glioma patients

BACKGROUND

Diffuse gliomas (WHO grade II-IV) are progressive primary brain tumors with great variability in prognosis. Cognitive deficits are of important prognostic value for survival in diffuse gliomas. Until now, few studies focused on domain-specific neuropsychological assessment and rather used MMSE as a measure for cognitive functioning. Additionally, these studies did not take WHO 2016 diagnosis into account. We performed a retrospective cohort study with the aim to investigate the independent relationship between cognitive functioning and survival in treatment-naive patients undergoing awake surgery for a diffuse glioma.

METHODS

In patients undergoing awake craniotomy between 2010 and 2017, we performed pre-operative neuropsychological assessments in five cognitive domains, with special attention for the domains executive functioning and memory. We evaluated the independent relation between these domains and survival, in a Cox proportional hazards model that included state-of-the-art integrated histomolecular ('layered' or WHO-2016) classification of the gliomas and other known prognostic factors.

RESULTS

We included 197 patients. Cognitive impairments (Z-values ≦ - 2.0) were most frequent in the domains memory (18.3%) and executive functioning (25.9%). Impairments in executive functioning and memory were significantly correlated with survival, even after correcting for the possible confounders. Analyses with the domains language, psychomotor speed, and visuospatial functioning yielded no significant results. Extensive domain-specific neuropsychological assessment was more strongly correlated to survival than MMSE.

CONCLUSION

Cognitive functioning is independently related to survival in diffuse glioma patients. Possible mechanisms underlying this relationship include the notion of cognitive functioning as a marker for diffuse infiltration of the tumor and the option that cognitive functioning and survival are determined by overlapping genetic pathways and biomarkers.

The adult human subventricular zone: partial ependymal coverage and proliferative capacity of cerebrospinal fluid

Neurogenesis continues throughout adulthood in specialized regions of the brain. One of these regions is the subventricular zone. During brain development, neurogenesis is regulated by a complex interplay of intrinsic and extrinsic cues that control stem-cell survival, renewal and cell lineage specification. Cerebrospinal fluid (CSF) is an integral part of the neurogenic niche in development as it is in direct contact with radial glial cells, and it is important in regulating proliferation and migration. Yet, the effect of CSF on neural stem cells in the subventricular zone of the adult human brain is unknown. We hypothesized a persistent stimulating effect of ventricular CSF on neural stem cells in adulthood, based on the literature, describing bulging accumulations of subventricular cells where CSF is in direct contact with the subventricular zone. Here, we show by immunohistochemistry on post-mortem adult human subventricular zone sections that neural stem cells are in close contact with CSF via protrusions through both intact and incomplete ependymal layers. We are the first to systematically quantify subventricular glial nodules denuded of ependyma and consisting of proliferating neural stem and progenitor cells, and showed that they are present from foetal age until adulthood. Neurosphere, cell motility and differentiation assays as well as analyses of RNA expression were used to assess the effects of CSF of adult humans on primary neural stem cells and a human immortalized neural stem cell line. We show that human ventricular CSF increases proliferation and decreases motility of neural stem cells. Our results also indicate that adult CSF pushes neural stem cells from a relative quiescent to a more active state and promotes neuronal over astrocytic lineage differentiation. Thus, CSF continues to stimulate neural stem cells throughout aging.

A Novel miR-146a-POU3F2/SMARCA5 Pathway Regulates Stemness and Therapeutic Response in Glioblastoma

Rapid tumor growth, widespread brain-invasion, and therapeutic resistance critically contribute to glioblastoma (GBM) recurrence and dismal patient outcomes. Although GBM stem cells (GSC) are shown to play key roles in these processes, the molecular pathways governing the GSC phenotype (GBM-stemness) remain poorly defined. Here, we show that epigenetic silencing of miR-146a significantly correlated with worse patient outcome and importantly, miR-146a level was significantly lower in recurrent tumors compared with primary ones. Further, miR-146a overexpression significantly inhibited the proliferation and invasion of GBM patient-derived primary cells and increased their response to temozolomide (TMZ), both in vitro and in vivo. Mechanistically, miR-146a directly silenced POU3F2 and SMARCA5, two transcription factors that mutually regulated each other, significantly compromising GBM-stemness and increasing TMZ response. Collectively, our data show that miR-146a-POU3F2/SMARCA5 pathway plays a critical role in suppressing GBM-stemness and increasing TMZ-response, suggesting that POU3F2 and SMARCA5 may serve as novel therapeutic targets in GBM. IMPLICATIONS: miR-146a predicts favorable prognosis and the miR-146a-POU3F2/SMARCA5 pathway is important for the suppression of stemness in GBM.

Single-Arm, Open-Label, Multicenter Study to Evaluate the Safety and Performance of Dura Sealant Patch in Reducing Cerebrospinal Fluid Leakage Following Elective Cranial Surgery: The ENCASE Trial Study Protocol

BACKGROUND

Cerebrospinal fluid (CSF) leakage is one of the most common neurosurgical complications, occurring in 4% to 32% of surgical cases, with a higher incidence in complicated skull base surgery, intradural spine surgery, and the surgery of the posterior fossa. Our group developed a Dural Sealant Patch (DSP) for watertight dural closure after cranial surgery.

OBJECTIVE

To clinically study for the first time the safety and performance of the DSP as a means of reducing CSF leakage in patients undergoing elective cranial intradural surgery with a dural closure procedure.

METHODS

We will conduct an open-label, single-arm, multicenter study with a 360 d (12 mo) follow-up. A total of 40 patients will be enrolled at 3 sites. The primary endpoint is a combination of occurrences of one of the following events: postoperative percutaneous CSF leakage, intraoperative leakage at 20 cm H2O, or postoperative wound infection. The secondary endpoints are pseudomeningocele and thickness of dura + DSP.

EXPECTED OUTCOMES

Not more than 3 patients will meet the primary endpoint suggesting safety and efficacy.

DISCUSSION

As a next step, a randomized controlled trial against the best current practice will follow to evaluate if DSP reduces CSF leakage while its safety is noninferior.

Quantifying eloquent locations for glioblastoma surgery using resection probability maps

OBJECTIVE

Decisions in glioblastoma surgery are often guided by presumed eloquence of the tumor location. The authors introduce the "expected residual tumor volume" (eRV) and the "expected resectability index" (eRI) based on previous decisions aggregated in resection probability maps. The diagnostic accuracy of eRV and eRI to predict biopsy decisions, resectability, functional outcome, and survival was determined.

METHODS

Consecutive patients with first-time glioblastoma surgery in 2012-2013 were included from 12 hospitals. The eRV was calculated from the preoperative MR images of each patient using a resection probability map, and the eRI was derived from the tumor volume. As reference, Sawaya's tumor location eloquence grades (EGs) were classified. Resectability was measured as observed extent of resection (EOR) and residual volume, and functional outcome as change in Karnofsky Performance Scale score. Receiver operating characteristic curves and multivariable logistic regression were applied.

RESULTS

Of 915 patients, 674 (74%) underwent a resection with a median EOR of 97%, functional improvement in 71 (8%), functional decline in 78 (9%), and median survival of 12.8 months. The eRI and eRV identified biopsies and EORs of at least 80%, 90%, or 98% better than EG. The eRV and eRI predicted observed residual volumes under 10, 5, and 1 ml better than EG. The eRV, eRI, and EG had low diagnostic accuracy for functional outcome changes. Higher eRV and lower eRI were strongly associated with shorter survival, independent of known prognostic factors.

CONCLUSIONS

The eRV and eRI predict biopsy decisions, resectability, and survival better than eloquence grading and may be useful preoperative indices to support surgical decisions.

Distance Control and Virtual Drilling Improves Anatomical Orientation During Anterior Petrosectomy

BACKGROUND

A combined drill distance control and virtual drilling image guidance feedback method was developed.

OBJECTIVE

To investigate whether first-time usage of the proposed method, during anterior petrosectomy (AP), improves surgical orientation and surgical performance. The accuracy of virtual drilling and the clinical practicability of the method were also investigated.

METHODS

In a simulated surgical setting using human cadavers, a trial was conducted with 5 expert skull base surgeons from 3 different hospitals. They performed 10 AP approaches, using either the feedback method or standard image guidance. Damage to critical structures was assessed. Operating time, drill cavity sizes, and proximity of postoperative drill cavities to the cochlea and the acoustic meatus, were measured. Questionnaires were obtained postoperatively. Errors in the virtual drill cavities as compared with actual postoperative cavities were calculated. In a clinical setup, the method was used during AP.

RESULTS

Surgeons rated their intraoperative orientation significantly better with the feedback method compared with standard image guidance. During the cadaver trial, the cochlea was harmed on 1 occasion in the control group, while surgeons drilled closer to the cochlea and meatus without injuring them in the group using feedback. Virtual drilling under- and overestimation errors were 2.2 ± 0.2 and −3.0 ± 0.6 mm on average. The method functioned properly during the clinical setup.

CONCLUSION

The proposed feedback method improves orientation and surgical performance in an experimental setting. Errors in virtual drilling reflect spatial errors of the image guidance system. The feedback method is clinically practicable during AP.

Neurocognitive changes after awake surgery in glioma patients: a retrospective cohort study

PURPOSE

Deficits in neurocognitive functioning (NCF) frequently occur in glioma patients. Both treatment and the tumor itself contribute to these deficits. In order to minimize the harmful effects of surgery, an increasing number of patients undergo awake craniotomy. To investigate whether we can indeed preserve cognitive functioning after state-of-the art awake surgery and to identify factors determining postoperative NCF, we performed a retrospective cohort study.

METHODS

In diffuse glioma (WHO grade 2-4) patients undergoing awake craniotomy, we studied neurocognitive functioning both pre-operatively and 3-6 months postoperatively. Evaluation covered five neurocognitive domains. We performed analysis of data on group and individual level and evaluated the value of patient-, tumor- and treatment-related factors for predicting change in NCF, using linear and logistic regression analysis.

RESULTS

We included 168 consecutive patients. Mean NCF-scores of psychomotor speed and visuospatial functioning significantly deteriorated after surgery. The percentage of serious neurocognitive impairments (- 2 standard deviations) increased significantly for psychomotor speed only. Tumor involvement in the left thalamus predicted a postoperative decline in NCF for the domains overall-NCF, executive functioning and psychomotor speed. An IDH-wildtype status predicted decline for overall-NCF and executive functioning.

CONCLUSIONS

In all cognitive domains, except for psychomotor speed, cognitive functioning can be preserved after awake surgery. The domain of psychomotor speed seems to be most vulnerable to the effects of surgery and early postoperative therapies. Cognitive performance after glioma surgery is associated with a combination of structural and biomolecular effects from the tumor, including IDH-status and left thalamic involvement.

Tumor-related neurocognitive dysfunction in patients with diffuse glioma: a retrospective cohort study prior to antitumor treatment

BACKGROUND

Impairments in neurocognitive functioning (NCF) frequently occur in glioma patients. Both the tumor and its treatment contribute to these impairments. We aimed to quantify NCF in glioma patients before treatment and to investigate which factors influence NCF.

METHODS

We performed a retrospective cohort study in diffuse glioma patients according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) criteria. All patients had undergone neuropsychological assessment as part of routine clinical care, before awake surgery. We studied "overall NCF" and NCF in 5 neurocognitive domains separately. For "overall NCF" and per domain, we performed analyses at 2 different levels of outcome measures: (1) group level: mean cognitive functioning of the study sample, and (2) individual level: the percentage of impaired patients. We performed multivariable logistic regression analyses to investigate which factors were associated with the occurrence of cognitive impairments.

RESULTS

From our cohort of glioma patients (2010-2016), 168 patients met all the inclusion criteria. All cognitive domains were significantly affected at the group level. The percentages of neurocognitive impairments (-2SD) were highest for Executive Functioning, Psychomotor Speed, and Memory (26.5%, 23.2%, and 19.3%, respectively). Patients with high-grade glioma were affected more severely than patients with low-grade glioma. Tumor volume, isocitrate dehydrogenase status, WHO grade, and histology were associated with the occurrence of domain-specific impairments.

CONCLUSIONS

Cognitive impairment occurs in the majority of treatment-naive glioma patients. The domains Executive Functioning, Speed, and Memory are involved most frequently. These impairments in NCF are explained not only by tumor location and volume, but also by other (biological) mechanisms.

Molecular Evolution of IDH Wild-Type Glioblastomas Treated With Standard of Care Affects Survival and Design of Precision Medicine Trials: A Report From the EORTC 1542 Study

PURPOSE

Precision medicine trials in glioblastoma (GBM) are often conducted at tumor recurrence. However, second surgeries for recurrent GBM are not routinely performed, and therefore, molecular data for trial inclusion are predominantly derived from the primary sample. This study aims to establish whether molecular targets change during tumor progression and, if so, whether this affects precision medicine trial design.

MATERIALS AND METHODS

We collected 186 pairs of primary-recurrent GBM samples from patients receiving chemoradiotherapy with temozolomide and sequenced approximately 300 cancer genes. MGMT, TERT, and EGFRvIII status was individually determined.

RESULTS

The molecular profile of our cohort was identical to that of other GBM cohorts (IDH wild-type [WT], 95%; EGFR amplified, approximately 50%), indicating that patients amenable to second surgery do not represent a specific molecular subtype. Molecular events in IDH WT GBMs were stable in approximately 80% of events, but changes in mutation status were observed for all examined genes (range, approximately 90% and 60% for TERT and EGFR mutations, respectively), and such changes strongly affected targeted trial size and design. A similar pattern of GBM driver instability was observed within MGMT promoter-methylated tumors. MGMT promoter methylation status remained prognostic at tumor recurrence. The observation that hypermutation at GBM recurrence was rare (8%) and not correlated with outcome was relevant for immunotherapy-based treatments.

CONCLUSION

This large cohort of matched primary and recurrent IDH WT tumors establishes the frequency of GBM driver instability after chemoradiotherapy with temozolomide. This allows per gene or pathway calculation of trial size at tumor recurrence, using molecular data of the primary tumor only. We also identify genes for which repeat surgery is necessary because of low mutation retention rate.