Ventricle contact is associated with lower survival and increased peritumoral perfusion in glioblastoma

The DNA Double-Strand Break Repair in Glioma: Molecular Players and Therapeutic Strategies

Gliomas are the most frequent type of tumor in the central nervous system, which exhibit properties that make their treatment difficult, such as cellular infiltration, heterogeneity, and the presence of stem-like cells responsible for tumor recurrence. The response of this type of tumor to chemoradiotherapy is poor, possibly due to a higher repair activity of the genetic material, among other causes. The DNA double-strand breaks are an important type of lesion to the genetic material, which have the potential to trigger processes of cell death or cause gene aberrations that could promote tumorigenesis. This review describes how the different cellular elements regulate the formation of DNA double-strand breaks and their repair in gliomas, discussing the therapeutic potential of the induction of this type of lesion and the suppression of its repair as a control mechanism of brain tumorigenesis.

Hyperintense signal on diffusion-weighted imaging for monitoring the acute response and local recurrence after photodynamic therapy in malignant gliomas

PURPOSE

Photodynamic therapy (PDT) subsequent to surgical tumor removal is a novel localized treatment for malignant glioma that provides effective local control. The acute response of malignant glioma to PDT can be detected as linear transient hyperintense signal on diffusion-weighted imaging (DWI) and a decline in apparent diffusion coefficient values without symptoms. However, their long-term clinical significance has not yet been examined. The aim of this study was to clarify the link between hyperintense signal on DWI as an acute response and recurrence after PDT in malignant glioma.

METHODS

Thirty patients (16 men; median age, 60.5 years) underwent PDT for malignant glioma at our institution between 2017 and 2020. We analyzed the signal changes on DWI after PDT and the relationship between these findings and the recurrence pattern.

RESULTS

All patients showed linear hyperintense signal on DWI at the surface of the resected cavity from day 1 after PDT. These changes disappeared in about 30 days without any neurological deterioration. During a mean post-PDT follow-up of 14.3 months, 19 patients (63%) exhibited recurrence: 10 local, 1 distant, and 8 disseminated. All of the local recurrences arose from areas that did not show hyperintense signal on DWI obtained on day 1 after PDT.

CONCLUSIONS

The local recurrence in malignant glioma after PDT occurs in an area without hyperintense signal on DWI as an acute response to PDT. This characteristic finding could aid in the monitoring of local recurrence after PDT.

Ventricle contact may be associated with higher 11C methionine PET uptake in glioblastoma

Purpose

Ventricle contact is associated with a worse prognosis and more aggressive tumor characteristics in glioblastoma (GBM). This is hypothesized to be a result of neural stem cells located around the lateral ventricles, in the subventricular zone. 11C Methionine positron emission tomography (metPET) is an indicator for increased proliferation, as it shows uptake of methionine, an amino acid needed for protein synthesis. This study is the first to study metPET characteristics of GBM in relation to ventricle contact.

Methods

A total of 12 patients with IDH wild-type GBM were included. Using MRI, the following regions were determined: primary tumor (defined as contrast enhancing lesion on T1) and peritumoral edema (defined as edema visible on FLAIR excluding the enhancement). PET parameters in these areas were extracted using PET fused with MRI imaging. Parameters extracted from the PET included maximum and mean tumor-to-normal ratio (TNRmax and TNRmean) and metabolic tumor volume (MTV).

Results

TNRmean of the primary tumor showed significantly higher values for the ventricle-contacting group compared to that for the non-contacting group (4.44 vs 2.67, p = 0.030). Other metPET parameters suggested higher values for the ventricle-contacting group, but these differences did not reach statistical significance.

Conclusion

GBM with ventricle contact demonstrated a higher methionine uptake and might thus have increased proliferation compared with GBM without ventricle contact. This might explain survival differences and should be considered in treatment decisions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00234-021-02742-7.

Anti-PD-1 checkpoint blockade monotherapy in the orthotopic GL261 glioma model: the devil is in the detail

The GL261 cell line, syngeneic on the C57BL/6 background, has, since its establishment half a century ago in 1970, become the most commonly used immunocompetent murine model of glioblastoma. As immunotherapy has entered the mainstream of clinical discourse in the past decade, this model has proved its worth as a formidable opponent against various immunotherapeutic combinations. Although advances in surgical, radiological, and chemotherapeutic interventions have extended mean glioblastoma patient survival by several months, 5-year survival postdiagnosis remains below 5%. Immunotherapeutic interventions, such as the ones explored in the murine GL261 model, may prove beneficial for patients with glioblastoma. However, even common immunotherapeutic interventions in the GL261 model still have unclear efficacy, with wildly discrepant conclusions being made in the literature regarding this topic. Here, we focus on anti-PD-1 checkpoint blockade monotherapy as an example of this pattern. We contend that a fine-grained analysis of how biological variables (age, sex, tumor location, etc.) predict treatment responsiveness in this preclinical model will better enable researchers to identify glioblastoma patients most likely to benefit from checkpoint blockade immunotherapy moving forward.

A Neural Network Approach to Identify Glioblastoma Progression Phenotype from Multimodal MRI

The phenotypes of glioblastoma (GBM) progression after treatment are heterogeneous in both imaging and clinical prognosis. This study aims to apply radiomics and neural network analysis to preoperative multimodal MRI data to characterize tumor progression phenotypes. We retrospectively reviewed 41 patients with newly diagnosed cerebral GBM from 2009-2016 who comprised the machine learning training group, and prospectively included 18 patients from 2017-2018 for data validation. Preoperative MRI examinations included structural MRI, diffusion tensor imaging, and perfusion MRI. Tumor progression patterns were categorized as diffuse or localized. A supervised machine learning model and neural network-based models (VGG16 and ResNet50) were used to establish the prediction model of the pattern of progression. The diffuse progression pattern showed a significantly worse prognosis regarding overall survival (p = 0.032). A total of 153 of the 841 radiomic features were used to classify progression patterns using different machine learning models with an overall accuracy of 81% (range: 77.5-82.5%, AUC = 0.83-0.89). Further application of the pretrained ResNet50 and VGG 16 neural network models demonstrated an overall accuracy of 93.1 and 96.1%. The progression patterns of GBM are an important prognostic factor and can potentially be predicted by combining multimodal MR radiomics with machine learning.

Prognostic value of test(s) for O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation for predicting overall survival in people with glioblastoma treated with temozolomide

BACKGROUND

Glioblastoma is an aggressive form of brain cancer. Approximately five in 100 people with glioblastoma survive for five years past diagnosis. Glioblastomas that have a particular modification to their DNA (called methylation) in a particular region (the O6-methylguanine-DNA methyltransferase (MGMT) promoter) respond better to treatment with chemotherapy using a drug called temozolomide.

OBJECTIVES

To determine which method for assessing MGMT methylation status best predicts overall survival in people diagnosed with glioblastoma who are treated with temozolomide.

SEARCH METHODS

We searched MEDLINE, Embase, BIOSIS, Web of Science Conference Proceedings Citation Index to December 2018, and examined reference lists. For economic evaluation studies, we additionally searched NHS Economic Evaluation Database (EED) up to December 2014.

SELECTION CRITERIA

Eligible studies were longitudinal (cohort) studies of adults with diagnosed glioblastoma treated with temozolomide with/without radiotherapy/surgery. Studies had to have related MGMT status in tumour tissue (assessed by one or more method) with overall survival and presented results as hazard ratios or with sufficient information (e.g. Kaplan-Meier curves) for us to estimate hazard ratios. We focused mainly on studies comparing two or more methods, and listed brief details of articles that examined a single method of measuring MGMT promoter methylation. We also sought economic evaluations conducted alongside trials, modelling studies and cost analysis.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook all steps of the identification and data extraction process for multiple-method studies. We assessed risk of bias and applicability using our own modified and extended version of the QUality In Prognosis Studies (QUIPS) tool. We compared different techniques, exact promoter regions (5'-cytosine-phosphate-guanine-3' (CpG) sites) and thresholds for interpretation within studies by examining hazard ratios. We performed meta-analyses for comparisons of the three most commonly examined methods (immunohistochemistry (IHC), methylation-specific polymerase chain reaction (MSP) and pyrosequencing (PSQ)), with ratios of hazard ratios (RHR), using an imputed value of the correlation between results based on the same individuals.

MAIN RESULTS

We included 32 independent cohorts involving 3474 people that compared two or more methods. We found evidence that MSP (CpG sites 76 to 80 and 84 to 87) is more prognostic than IHC for MGMT protein at varying thresholds (RHR 1.31, 95% confidence interval (CI) 1.01 to 1.71). We also found evidence that PSQ is more prognostic than IHC for MGMT protein at various thresholds (RHR 1.36, 95% CI 1.01 to 1.84). The data suggest that PSQ (mainly at CpG sites 74 to 78, using various thresholds) is slightly more prognostic than MSP at sites 76 to 80 and 84 to 87 (RHR 1.14, 95% CI 0.87 to 1.48). Many variants of PSQ have been compared, although we did not see any strong and consistent messages from the results. Targeting multiple CpG sites is likely to be more prognostic than targeting just one. In addition, we identified and summarised 190 articles describing a single method for measuring MGMT promoter methylation status.

AUTHORS' CONCLUSIONS

PSQ and MSP appear more prognostic for overall survival than IHC. Strong evidence is not available to draw conclusions with confidence about the best CpG sites or thresholds for quantitative methods. MSP has been studied mainly for CpG sites 76 to 80 and 84 to 87 and PSQ at CpG sites ranging from 72 to 95. A threshold of 9% for CpG sites 74 to 78 performed better than higher thresholds of 28% or 29% in two of three good-quality studies making such comparisons.

The Nomogram of MRI-based Radiomics with Complementary Visual Features by Machine Learning Improves Stratification of Glioblastoma Patients: A Multicenter Study

BACKGROUND

Glioblastomas (GBMs) represent both the most common and the most highly malignant primary brain tumors. The subjective visual imaging features from MRI make it challenging to predict the overall survival (OS) of GBM. Radiomics can quantify image features objectively as an emerging technique. A pragmatic and objective method in the clinic to assess OS is strongly in need.

PURPOSE

To construct a radiomics nomogram to stratify GBM patients into long- vs. short-term survival.

STUDY TYPE

Retrospective.

POPULATION

One-hundred and fifty-eight GBM patients from Brain Tumor Segmentation Challenge 2018 (BRATS2018) were for model construction and 32 GBM patients from the local hospital for external validation.

FIELD STRENGTH/SEQUENCE

1.5 T and 3.0 T MRI Scanners, T₁ WI, T₂ WI, T₂ FLAIR, and contrast-enhanced T₁ WI sequences ASSESSMENT: All patients were divided into long-term or short-term based on a survival of greater or fewer than 12 months. All BRATS2018 subjects were divided into training and test sets, and images were assessed for ependymal and pia mater involvement (EPI) and multifocality by three experienced neuroradiologists. All tumor tissues from multiparametric MRI were fully automatically segmented into three subregions to calculate the radiomic features. Based on the training set, the most powerful radiomic features were selected to constitute radiomic signature.

STATISTICAL TESTS

Receiver operating characteristic (ROC) curve, sensitivity, specificity, and the Hosmer-Lemeshow test.

RESULTS

The nomogram had a survival prediction accuracy of 0.878 and 0.875, a specificity of 0.875 and 0.583, and a sensitivity of 0.704 and 0.833, respectively, in the training and test set. The ROC curve showed the accuracy of the nomogram, radiomic signature, age, and EPI for external validation set were 0.858, 0.826, 0.664, and 0.66 in the validate set, respectively.

DATA CONCLUSION

Radiomics nomogram integrated with radiomic signature, EPI, and age was found to be robust for the stratification of GBM patients into long- vs. short-term survival.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2.

Subventricular zone contacting glioblastoma: tumor size, molecular biological factors and patient survival

BACKGROUND

Several studies show that subventricular zone (SVZ) contact of glioblastoma at diagnosis is a negative prognosticator of survival. In this report, we study glioblastoma patient survival, molecular biological and MRI-based volumetric findings according to SVZ contact.

PATIENTS AND METHODS

We conducted a retrospective study of adult patients diagnosed with supratentorial glioblastoma and uniformly treated with temozolomide-based chemoradiotherapy after surgery. The patient cohort was dichotomized according to tumor contact with the SVZ at diagnosis as determined on preoperative MR imaging. Tumor volume was measured using semi-automated segmentation technique. MGMT-gene promoter methylation and IDH mutation status were determined on stored tumor tissue. Kaplan-Meier survival curves were constructed. Cox regression analysis was used to adjust for known confounding factors of glioblastoma patient survival.

RESULTS

A total of 214 patients were included in the study of whom 68% belonged to the SVZ_pos group. Median tumor volume was significantly larger in the SVZ_pos group (33,8 mL vs 15,6 mL; p < .001). MGMT-unmethylated glioblastoma was more frequent in the SVZ_pos group (61.4% vs 44.9%; p = .028). The overall survival and progression-free survival were 12.2 months and 5.9 months for the SVZ_pos patient group but 16.9 months and 10.3 months for the SVZ_neg group (log-rank p = .016 and .007 respectively). In multivariate Cox survival analysis, SVZ contact proved a negative prognostic parameter, independent from age, KPS, extent of resection, MGMT-methylation and IDH mutation status.

CONCLUSIONS

This study confirms SVZ contact at diagnosis as an independent negative prognostic factor for glioblastoma patient survival. SVZ_pos glioblastoma had larger tumor size and a larger proportion of unmethylated tumors than SVZ_neg glioblastoma. Further research is needed to establish whether the observed differences are solely explained by a different molecular profile of SVZ_pos glioblastoma or by interaction of glioblastoma with the unique SVZ microenvironment.

Association between supratentorial pediatric high-grade gliomas involved with the subventricular zone and decreased survival: a multi-institutional retrospective study

OBJECTIVE

The subventricular zone (SVZ), housed in the lateral walls of the lateral ventricles, is the largest neurogenic niche in the brain. In adults, high-grade gliomas in contact or involved with the SVZ are associated with decreased survival. Whether this association holds true in the pediatric population remains unexplored. To address this gap in knowledge, the authors conducted this retrospective study in a pediatric population with high-grade gliomas treated at three comprehensive centers in the United States.

METHODS

The authors retrospectively identified 63 patients, age ≤ 21 years, with supratentorial WHO grade III-IV gliomas treated at three academic centers. Basic demographic and clinical data regarding presenting signs and symptoms and common treatment variables were obtained. Preoperative MRI studies were evaluated to assess SVZ contact by tumor and to quantify tumor volume.

RESULTS

Sixty-three patients, including 34 males (54%), had a median age of 12.3 years (IQR 6.50-16.2) and a median tumor volume of 39.4 ml (IQR 19.4-65.8). Tumors contacting the SVZ (SVZ+) were noted in 34 patients (54%) and overall were larger than those not in contact with the SVZ (SVZ-; 51.1 vs 27.3, p = 0.002). The SVZ+ tumors were also associated with decreased survival. However, age, tumor volume, tumor grade, and treatment with chemotherapy and/or radiation were not associated with survival in the 63 patients. In the univariable analysis, near-total resection, gross-total resection, and seizure presentation were associated with increased survival (HR = 0.23, 95% CI 0.06-0.88, p = 0.03; HR = 0.26, 95% CI 0.09-0.74, p = 0.01; and HR = 0.46, 95% CI 0.22-0.97, p = 0.04, respectively). In a multivariable stepwise Cox regression analysis, only SVZ+ tumors remained significantly associated with decreased survival (HR = 1.94, 95% CI 1.03-3.64, p = 0.04).

CONCLUSIONS

High-grade glioma contact with the SVZ neural stem cell niche was associated with a significant decrease in survival in the pediatric population, as it is in the adult population. This result suggests that tumor contact with the SVZ is a general negative prognosticator in high-grade glioma independent of age group and invites biological investigations to understand the SVZ's role in glioma pathobiology.

Influence of wide opening of the lateral ventricle on survival for supratentorial glioblastoma patients with radiotherapy and concomitant temozolomide-based chemotherapy

The prognosis for glioblastoma (GBM) varies among patients. Ventricular opening during surgery has been reported as a prognostic factor for GBM patients, but the influence of ventricular opening itself on patient prognosis remains controversial. We presumed that the degree of ventricular opening would correlate with the degree of subventricular zone (SVZ) resection and with prognosis in GBM patients. This study therefore investigated whether the degree of ventricular opening correlates with prognosis in GBM patients treated with the standard protocol of chemo-radiotherapy. Participants comprised 111 patients with newly diagnosed GBM who underwent surgery and received postoperative radiotherapy and temozolomide-based chemotherapy from 2005 to 2018. We classified 111 patients into "No ventricular opening (NVO)", "Ventricular opening, small (VOS; distance < 23.2 mm)", and "Ventricular opening, wide (VOW; distance ≥ 23.2 mm)" groups. We evaluated the relationship between degree of ventricular opening and prognosis using survival analyses that included other clinicopathological factors. Log-rank testing revealed age, Karnofsky performance status (KPS), extent of resection, O6-methylguanine-DNA methyltransferase (MGMT) status, isocitrate dehydrogenase (IDH)1 mutation, and degree of ventricular opening correlated significantly with overall survival. Multivariate analysis identified the degree of ventricular opening (small vs. wide) as the most significant prognostic factor (hazard ratio = 3.674; p < 0.0001). We demonstrated that wide opening of the lateral ventricle (LV) contributes to longer survival compared with small opening among GBM patients. Our results indicate that wide opening of the LV may correlate with the removal of a larger proportion of tumor stem cells from the SVZ.