High-grade glioma management and response assessment-recent advances and current challenges

Efficacy and Safety of Vaccines After Conventional Treatments for Survival of Gliomas: A Systematic Review and Meta-Analysis

Background

Malignant gliomas are known with poor prognosis and low rate of survival among brain tumors. Resection surgery is followed by chemotherapy and radiotherapy in treatment of gliomas which is known as the conventional treatment. However, this treatment method results in low survival rate. Vaccination has been suggested as a type of immunotherapy to increase survival rate of glioma patients. Different types of vaccines have been developed that are mainly classified in two groups including peptide vaccines and cell-based vaccines. However, there are still conflicts about which type of vaccines is more efficient for malignant glioma treatment.

Methods

Phase Ⅰ/Ⅱ clinical trials which compared the efficacy and safety of various vaccines with conventional treatments were searched in databases through November 2022. Overall survival (OS) rate, progression free survival (PFS), and OS duration were used for calculation of pooled risk ratio (RR). In addition, fatigue, headache, nausea, diarrhea, and flu-like syndrome were used for evaluating the safety of vaccines therapy in glioma patients.

Results

A total of twelve articles were included in the present meta-analysis. Comparison of OS rate between vaccinated groups and control groups who underwent only conventional treatments showed a significant increase in OS rate in vaccinated patients (I2 = 0%, RR = 11.17, 95% CI: 2.460-50.225). PFS rate was better in vaccinated glioma patients (I2 = 83%, RR = 2.87, 95% CI: 1.63-5.03). Assessment of safety demonstrated that skin reaction (I2 = 0.0%, RR = 3.654; 95% CI: 1.711-7.801, p-value = 0.0058) and flu-like syndrome were significantly more frequent adverse effects win vaccinated groups compared to the control group. Subgroup analysis also showed that vaccination leads to better OS duration in recurrent gliomas than primary gliomas, and in LGG than HGG (p-value = 0). On the other hand, personalized vaccines showed better OS duration than non-personalized vaccines (p-value = 0).

Conclusion

Vaccination is a type of immunotherapy which shows promising efficacy in treatment of malignant glioma patients in terms of OS, PFS and duration of survival. In addition, AFTV, peptide, and dendritic cell-based vaccines are among the most efficient vaccines for gliomas. Personalized vaccines also showed considerable efficacy for glioma treatments.

Identification of prognostic risk score of disulfidptosis-related genes and molecular subtypes in glioma

Background

Programmed cell death is closely related to glioma. As a novel kind of cell death, the mechanism of disulfidptosis in glioma remains unclear. Therefore, it is of great importance to study the role of disulfidptosis-related genes (DRGs) in glioma.

Methods

We first investigated the genetic and transcriptional alterations of 15 DRGs. Two consensus cluster analyses were used to evaluate the association between DRGs and glioma subtypes. In addition, we constructed prognostic DRG risk scores to predict overall survival (OS) in glioma patients. Furthermore, we developed a nomogram to enhance the clinical utility of the DRG risk score. Finally, the expression levels of DRGs were verified by immunohistochemistry (IHC) staining.

Results

Most DRGs (14/15) were dysregulated in gliomas. The 15 DRGs were rarely mutated in gliomas, and only 50 of 987 samples (5.07 %) showed gene mutations. However, most of them had copy number variation (CNV) deletions or amplifications. Two distinct molecular subtypes were identified by cluster analysis, and DRG alterations were found to be related to the clinical characteristics, prognosis, and tumor immune microenvironment (TIME). The DRG risk score model based on 12 genes was developed and showed good performance in predicting OS. The nomogram confirmed that the risk score had a particularly strong influence on the prognosis of glioma. Furthermore, we discovered that low DRG scores, low tumor mutation burden, and immunosuppression were features of patients with better prognoses.

Conclusion

The DRG risk model can be used for the evaluation of clinical characteristics, prognosis prediction, and TIME estimation of glioma patients. These DRGs may be potential therapeutic targets in glioma.

Efficacy and Safety of Intraoperative Radiotherapy for High-Grade Gliomas: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

High-grade gliomas (HGGs) are aggressive tumors of the central nervous system that cause significant morbidity and mortality. Despite advances in surgery and radiation therapy (RT), HGG still has a high incidence of recurrence and treatment failure. Intraoperative radiotherapy (IORT) has emerged as a promising therapeutic approach to achieve local tumor control while sparing normal brain tissue from radiation-induced damage.

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines to evaluate the use of IORT for HGG. Eligible studies were included based on specific criteria, and data were independently extracted. Outcomes of interest included complications, IORT failure, survival rates at 12 and 24 months, and mortality.

RESULTS

Sixteen studies comprising 436 patients were included. The overall complication rate after IORT was 17%, with significant heterogeneity observed. The IORT failure rate was 77%, while the survival rates at 12 and 24 months were 74% and 24%, respectively. The mortality rate was 62%.

CONCLUSION

This meta-analysis suggests that IORT may be a promising adjuvant treatment for selected patients with HGG. Despite the high rate of complications and treatment failures, the survival outcomes were comparable or even superior to conventional methods. However, the limitations of the study, such as the lack of a control group and small sample sizes, warrant further investigation through prospective randomized controlled trials to better understand the specific patient populations that may benefit most from IORT. However, the limitations of the study, such as the lack of a control group and small sample sizes, warrant further investigation. Notably, the ongoing RP3 trial (NCT02685605) is currently underway, with the aim of providing a more comprehensive understanding of IORT. Moreover, future research should focus on managing complications associated with IORT to improve its safety and efficacy in treating HGG.

Review: therapeutic approaches for circadian modulation of the glioma microenvironment

High-grade gliomas are malignant brain tumors that are characteristically hard to treat because of their nature; they grow quickly and invasively through the brain tissue and develop chemoradiation resistance in adults. There is also a distinct lack of targeted treatment options in the pediatric population for this tumor type to date. Several approaches to overcome therapeutic resistance have been explored, including targeted therapy to growth pathways (ie. EGFR and VEGF inhibitors), epigenetic modulators, and immunotherapies such as Chimeric Antigen Receptor T-cell and vaccine therapies. One new promising approach relies on the timing of chemotherapy administration based on intrinsic circadian rhythms. Recent work in glioblastoma has demonstrated temporal variations in chemosensitivity and, thus, improved survival based on treatment time of day. This may be due to intrinsic rhythms of the glioma cells, permeability of the blood brain barrier to chemotherapy agents, the tumor immune microenvironment, or another unknown mechanism. We review the literature to discuss chronotherapeutic approaches to high-grade glioma treatment, circadian regulation of the immune system and tumor microenvironment in gliomas. We further discuss how these two areas may be combined to temporally regulate and/or improve the effectiveness of immunotherapies.

Evaluation of the Diagnostic Performance of F18-Fluorodeoxyglucose-Positron Emission Tomography, Dynamic Susceptibility Contrast Perfusion, and Apparent Diffusion Coefficient in Differentiation between Recurrence of a High-grade Glioma and Radiation Necrosis

Background

Differentiation between recurrence of brain tumor and radiation necrosis remains a challenge in current neuro-oncology practice despite recent advances in both radiological and nuclear medicine techniques.

Purpose

The purpose of this study was to compare the diagnostic performance of dynamic susceptibility contrast (DSC) perfusion magnetic resonance imaging (MRI), apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging, and F18-fluorodeoxyglucose-positron emission tomography (F18-FDG-PET) in the differentiation between the recurrence of a high-grade glioma and radiation necrosis.

Materials and Methods

Patients with a diagnosis of high-grade glioma (WHO Grades III and IV) who had undergone surgical resection of the tumor followed by radiotherapy with or without chemotherapy were included in the study. DSC perfusion, diffusion-weighted MRI, and PET scan were acquired on a hybrid PET/MRI scanner. For each lesion, early and delayed tumor-to-brain ratio (TBR), early and delayed maximum standardized uptake value (SUVmax), normalized ADC ratio, and normalized relative cerebral blood volume (rCBV) ratio were calculated and the pattern of lesional enhancement was noted. The diagnosis was finalized with either histopathological examination or the characteristics on follow-up imaging. The statistical analysis using the receiver operator characteristic curves was done to determine the diagnostic performance of DSC perfusion, 18-F FDG-PET, and ADC in differentiation between tumor recurrence and radiation necrosis.

Results

Fifty patients were included in the final analysis, 32 of them being men (64%). A cutoff value of early TBR >0.8 (sensitivity of 100% and specificity of 80%), delayed TBR >0.93 (sensitivity of 92.3% and specificity of 80%), early SUVmax >10.2 (sensitivity of 76.9% and specificity of 80%), delayed SUVmax >13.2 (sensitivity of 61.54% and specificity of 100%), normalized rCBV ratio >1.21 (sensitivity of 100% and specificity of 60%), normalized ADC ratio >1.66 (sensitivity of 38.5% and specificity of 80%), and Grade 3 enhancement (sensitivity of 100% and specificity of 60%) were found to differentiate recurrence from radiation necrosis. Early TBR had the highest accuracy (94.44%), while ADC ratio had the lowest accuracy (50%). A combination of early TBR (cutoff value of 0.8), late TBR (cutoff value of 0.93), and rCBV ratio (cutoff value of 1.21) showed a sensitivity of 100%, specificity of 92.3%, positive predictive value of 88.9%, negative predictive value of 93.7%, and an accuracy of 96.6% in discrimination between radiation necrosis and recurrence of tumor.

Conclusion

F18-FDG-PET and DSC perfusion can reliably differentiate tumor recurrence from radiation necrosis, with early TBR showing the highest accuracy. ADC demonstrates a low sensitivity, specificity, and accuracy in differentiating radiation necrosis from recurrence. A combination of early TBR, delayed TBR, and rCBV may be more useful in discrimination between radiation necrosis and recurrence of glioma, with this combination showing a better diagnostic performance than individual parameters or any other combination of parameters.

Molecular characteristics of incidental lower-grade glioma for treatment decision-making

OBJECTIVE

Several limitations are associated with the early diagnosis and treatment of incidental lower-grade glioma (iLGG), and due to its unknown molecular features, its management is categorized as either the "wait-and-see" strategy or immediate treatment. Therefore, in this study the authors explored iLGG's clinical and molecular landscape to improve its management.

METHODS

The authors retrospectively assessed the differences between the molecular and clinical characteristics of iLGG and symptomatic lower-grade glioma (sLGG) samples filtered based on symptom data corresponding to The Cancer Genome Atlas cohort with mutations. Thereafter, genomic and transcriptomic analysis was performed.

RESULTS

There was no significant difference between iLGG and sLGG with respect to mutation status; however, there was an increase in the interaction between major mutations in sLGG, depending on the histological subtype and the IDH1 mutation status. Furthermore, the IDH1 mutation characteristics corresponding to wild-type glioma were much more obvious in sLGG than in iLGG. Additionally, in sLGG, genes associated with malignancy, including cell proliferation-related, cell migration-related, epithelial-to-mesenchymal transition-related, and negative regulation of cell death-related genes, were significantly upregulated, and groups showing higher expression levels of these genes were associated with worse prognosis. Also, 8 of the 75 identified upregulated genes showed positive correlation with resistance to the drugs that are normally used for glioma treatment, including procarbazine, carmustine, vincristine, and temozolomide.

CONCLUSIONS

The new insights regarding the different molecular features of iLGG and sLGG indicated that the immediate management of iLGG could result in better prognosis than the wait-and-see strategy.

Anticancer Mechanism of Flavonoids on High-Grade Adult-Type Diffuse Gliomas

High-grade adult-type diffuse gliomas are the most common and deadliest malignant adult tumors of the central nervous system. Despite the advancements in the multimodality treatment of high-grade adult-type diffuse gliomas, the five-year survival rates still remain poor. The biggest challenge in treating high-grade adult-type diffuse gliomas is the intra-tumor heterogeneity feature of the glioma tumors. Introducing dietary flavonoids to the current high-grade adult-type diffuse glioma treatment strategies is crucial to overcome this challenge, as flavonoids can target several molecular targets. This review discusses the anticancer mechanism of flavonoids (quercetin, rutin, chrysin, apigenin, naringenin, silibinin, EGCG, genistein, biochanin A and C3G) through targeting molecules associated with high-grade adult-type diffuse glioma cell proliferation, apoptosis, oxidative stress, cell cycle arrest, migration, invasion, autophagy and DNA repair. In addition, the common molecules targeted by the flavonoids such as Bax, Bcl-2, MMP-2, MMP-9, caspase-8, caspase-3, p53, p38, Erk, JNK, p38, beclin-1 and LC3B were also discussed. Moreover, the clinical relevance of flavonoid molecular targets in high-grade adult-type diffuse gliomas is discussed with comparison to small molecules inhibitors: ralimetinib, AMG232, marimastat, hydroxychloroquine and chloroquine. Despite the positive pre-clinical results, further investigations in clinical studies are warranted to substantiate the efficacy and safety of the use of flavonoids on high-grade adult-type diffuse glioma patients.

Assessment of the hypervascularized fraction of glioblastomas using a volume analysis of dynamic susceptibility contrast-enhanced MRI may help to identify pseudoprogression

PURPOSE

Although perfusion magnetic resonance imaging (MRI) is widely used to identify pseudoprogression, this advanced technique lacks clinical reliability. Our aim was to develop a parameter assessing the hypervascularized fraction of glioblastomas based on volume analysis of dynamic susceptibility contrast-enhanced MRI and evaluate its performance in the diagnosis of pseudoprogression.

METHODS

Patients with primary glioblastoma showing lesion progression on the first follow-up MRI after chemoradiotherapy were enrolled retrospectively. On both initial and first follow-up MRIs, the leakage-corrected cerebral blood volume (CBV) maps were post-processed using the conventional hot-spot method and a volume method, after manual segmentation of the contrast-enhanced delineated lesion. The maximum CBV (rCBVmax) was calculated with both methods. Secondly, the threshold of 2 was applied to the CBV values contained in the entire segmented volume, defining our new parameter: %rCBV>2. The probability of pseudoprogression based on rCBVmax and %rCBV>2 was calculated in logistic regression models and diagnostic performance assessed by receiving operator characteristic curves.

RESULTS

Out of 25 patients, 11 (44%) were classified with pseudoprogression and 14 (56%) with true progression based on the Response Assessement in Neuro-Oncology criteria. rCBVmax was lower for pseudoprogression (3.4 vs. 7.6; p = 0.033) on early follow-up MRI. %rCBV>2, was lower for pseudoprogression on both initial (57.5% vs. 71.3%; p = 0.033) and early follow-up MRIs (22.1% vs. 51.8%; p = 0.0006). On early follow-up MRI, %rCBV>2 had the largest area under the curve for the diagnosis of pseudoprogression: 0.909 [0.725-0.986].

CONCLUSION

The fraction of hypervascularization of glioblastomas as assessed by %rCBV>2 was lower in tumours that subsequently developed pseudoprogression both on the initial and early follow-up MRIs. This fractional parameter may help identify pseudoprogression with greater accuracy than rCBVmax.

Treatment Response and Prognosis Evaluation in High-Grade Glioma: An Imaging Review Based on MRI

In recent years, the development of advanced magnetic resonance imaging (MRI) technology and machine learning (ML) have created new tools for evaluating treatment response and prognosis of patients with high-grade gliomas (HGG); however, patient prognosis has not improved significantly. This is mainly due to the heterogeneity between and within HGG tumors, resulting in standard treatment methods not benefitting all patients. Moreover, the survival of patients with HGG is not only related to tumor cells, but also to noncancer cells in the tumor microenvironment (TME). Therefore, during preoperative diagnosis and follow-up treatment of patients with HGG, noninvasive imaging markers are needed to characterize intratumoral heterogeneity, and then to evaluate treatment response and predict prognosis, timeously adjust treatment strategies, and achieve individualized diagnosis and treatment. In this review, we summarize the research progress of conventional MRI, advanced MRI technology, and ML in evaluation of treatment response and prognosis of patients with HGG. We further discuss the significance of the TME in the prognosis of HGG patients, associate imaging features with the TME, indirectly reflecting the heterogeneity within the tumor, and shifting treatment strategies from tumor cells alone to systemic therapy of the TME, which may be a major development direction in the future. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 4.

Tracking the Corticospinal Tract in Patients With High-Grade Glioma: Clinical Evaluation of Multi-Level Fiber Tracking and Comparison to Conventional Deterministic Approaches

While the diagnosis of high-grade glioma (HGG) is still associated with a considerably poor prognosis, neurosurgical tumor resection provides an opportunity for prolonged survival and improved quality of life for affected patients. However, successful tumor resection is dependent on a proper surgical planning to avoid surgery-induced functional deficits whilst achieving a maximum extent of resection (EOR). With diffusion magnetic resonance imaging (MRI) providing insight into individual white matter neuroanatomy, the challenge remains to disentangle that information as correctly and as completely as possible. In particular, due to the lack of sensitivity and accuracy, the clinical value of widely used diffusion tensor imaging (DTI)-based tractography is increasingly questioned. We evaluated whether the recently developed multi-level fiber tracking (MLFT) technique can improve tractography of the corticospinal tract (CST) in patients with motor-eloquent HGGs. Forty patients with therapy-naïve HGGs (mean age: 62.6 ± 13.4 years, 57.5% males) and preoperative diffusion MRI [repetition time (TR)/echo time (TE): 5000/78 ms, voxel size: 2x2x2 mm3, one volume at b=0 s/mm2, 32 volumes at b=1000 s/mm2] underwent reconstruction of the CST of the tumor-affected and unaffected hemispheres using MLFT in addition to deterministic DTI-based and deterministic constrained spherical deconvolution (CSD)-based fiber tractography. The brain stem was used as a seeding region, with a motor cortex mask serving as a target region for MLFT and a region of interest (ROI) for the other two algorithms. Application of the MLFT method substantially improved bundle reconstruction, leading to CST bundles with higher radial extent compared to the two other algorithms (delineation of CST fanning with a wider range; median radial extent for tumor-affected vs. unaffected hemisphere - DTI: 19.46° vs. 18.99°, p=0.8931; CSD: 30.54° vs. 27.63°, p=0.0546; MLFT: 81.17° vs. 74.59°, p=0.0134). In addition, reconstructions by MLFT and CSD-based tractography nearly completely included respective bundles derived from DTI-based tractography, which was however favorable for MLFT compared to CSD-based tractography (median coverage of the DTI-based CST for affected vs. unaffected hemispheres - CSD: 68.16% vs. 77.59%, p=0.0075; MLFT: 93.09% vs. 95.49%; p=0.0046). Thus, a more complete picture of the CST in patients with motor-eloquent HGGs might be achieved based on routinely acquired diffusion MRI data using MLFT.

Monoexponential, biexponential and stretched exponential models of diffusion weighted magnetic resonance imaging in glioma in relation to histopathologic grade and Ki-67 labeling index using high B values

PURPOSE

To explore the performance of various parameters obtained from monoexponential (Gaussian), biexponential and stretched exponential (non-Gaussian) models of Diffusion Weighted Magnetic Resonance Imaging in differentiating gliomas with correlation to histopathology and Ki-67 labeling index (LI).

MATERIALS AND METHODS

This Institute Review Board approved retrospective study included 51 pathologically proven glioma patients (WHO Grade I, n = 1; Grade II, n = 19, Grade III, n = 12; Grade IV, n = 19), and immunohistochemistry for Ki-67 LI was obtained. The conventional Magnetic Resonance (MR) images and Diffusion Weighted (DW) images with 19 non-zero b values (0-4500 s/mm²) followed by contrast-enhanced MR images were obtained at 3T preoperatively. All images were processed with Advantage Workstation 4.5 (GE Medical Systems). Region of interest (ROI) in the solid part of the tumor was manually drawn along the border meticulously excluding areas of edema, cyst, hemorrhage, necrosis, and/or calcification, and the parameters: Apparent Diffusion Coefficient (ADC) of monoexponential; pure molecular diffusion coefficient (Dslow), pseudo-diffusion coefficient (Dfast), and perfusion fraction (f) of biexponential; Distributed Diffusion Coefficient (DDC), and heterogeneity index (α) of stretched exponential models were obtained. ROI of 50 mm² in the contralateral normal appearing white matter (NAWM) was drawn for the internal control either on centrum semiovale or white matter of the frontal lobe. Analysis of reliability by Intra-class Correlation Coefficient (ICC); correlation with Ki-67 LI by Spearman's rank correlation; comparison between high grade glioma (HGG) and low grade glioma (LGG) by either Mann Whitney U test or Independent t-Test; comparison among Grade II, III and IV gliomas by one-way ANOVA with Bonferroni; and diagnostic performance by analysis of Area Under Receiver Operating Characteristic (ROC) Curve (AUC) were conducted.

RESULTS

Highly significant differences were found between HGG and LGG for all the parameters (P < 0.001 for all). In differentiating HGG from LGG, AUC values were 0.955 for Ki-67 LI; 0.926 for α; 0.903 for Dslow; 0.897 for f; 0.863 for DDC; 0.852 for ADC; 0.820 for Dfast (P < 0.001 for all). The parameters ADC, Dslow, Dfast, f, DDC, and α showed moderate to good negative correlation with Ki-67 LI (P < 0.001 for all). The ICCs of all the parameters were found greater than 0.75 (P < 0.05 for all) suggesting good reliability of measurements.

CONCLUSION

In comparison to ADC derived from monoexponential model, the parameters α and Dslow derived from stretched exponential, and biexponential models respectively can efficiently differentiate HGG from LGG with high diagnostic accuracy. Additionally, f and DDC derived from biexponential, and stretched exponential models respectively are also more useful in differentiating HGG from LGG in comparison to ADC.

Challenges and Perspectives of Standard Therapy and Drug Development in High-Grade Gliomas

Despite their low incidence rate globally, high-grade gliomas (HGG) remain a fatal primary brain tumor. The recommended therapy often is incapable of resecting the tumor entirely and exclusively targeting the tumor leads to tumor recurrence and dismal prognosis. Additionally, many HGG patients are not well suited for standard therapy and instead, subjected to a palliative approach. HGG tumors are highly infiltrative and the complex tumor microenvironment as well as high tumor heterogeneity often poses the main challenges towards the standard treatment. Therefore, a one-fit-approach may not be suitable for HGG management. Thus, a multimodal approach of standard therapy with immunotherapy, nanomedicine, repurposing of older drugs, use of phytochemicals, and precision medicine may be more advantageous than a single treatment model. This multimodal approach considers the environmental and genetic factors which could affect the patient's response to therapy, thus improving their outcome. This review discusses the current views and advances in potential HGG therapeutic approaches and, aims to bridge the existing knowledge gap that will assist in overcoming challenges in HGG.

Three-dimensional visualization of brain tumor progression based accurate segmentation via comparative holographic projection

We propose a new optical method based on comparative holographic projection for visual comparison between two abnormal follow-up magnetic resonance (MR) exams of glioblastoma patients to effectively visualize and assess tumor progression. First, the brain tissue and tumor areas are segmented from the MR exams using the fast marching method (FMM). The FMM approach is implemented on a computed pixel weight matrix based on an automated selection of a set of initialized target points. Thereafter, the associated phase holograms are calculated for the segmented structures based on an adaptive iterative Fourier transform algorithm (AIFTA). Within this approach, a spatial multiplexing is applied to reduce the speckle noise. Furthermore, hologram modulation is performed to represent two different reconstruction schemes. In both schemes, all calculated holograms are superimposed into a single two-dimensional (2D) hologram which is then displayed on a reflective phase-only spatial light modulator (SLM) for optical reconstruction. The optical reconstruction of the first scheme displays a 3D map of the tumor allowing to visualize the volume of the tumor after treatment and at the progression. Whereas, the second scheme displays the follow-up exams in a side-by-side mode highlighting tumor areas, so the assessment of each case can be fast achieved. The proposed system can be used as a valuable tool for interpretation and assessment of the tumor progression with respect to the treatment method providing an improvement in diagnosis and treatment planning.

FDPS promotes glioma growth and macrophage recruitment by regulating CCL20 via Wnt/β-catenin signalling pathway

Glioma is one of the most lethal tumours and common malignant in the central nervous system (CNS), which exhibits diffuse invasion and aggressive growth. Several studies have reported the association of FDPS to tumour development and progression. However, the role of FDPS in progression of glioma and macrophage recruitment is not well‐elucidated. In the current study, a remarkable enhancement in FDPS level was observed in glioma tissues and associated with poor prognosis, contributed to tumour growth. FDPS was correlated with macrophage infiltration in glioma and pharmacological deletion of macrophages largely abrogated the oncogenic functions of FDPS in glioma. Mechanistically, FDPS activated Wnt/β‐catenin signalling pathway and ultimately facilitates macrophage infiltration by inducing CCL20 expression. In conclusion, overexpressed FDPS exhibits an immunomodulatory role in glioma. Therefore, targeting FDPS may be an effective therapeutic strategy for glioma.

Meta-analysis of the diagnostic performance of diffusion magnetic resonance imaging with apparent diffusion coefficient measurements for differentiating glioma recurrence from pseudoprogression

OBJECTIVE

The accurate differentiation of glioma recurrence from pseudoprogression (PSP) after therapy remains a considerable clinical challenge. Several studies have shown that diffusion magnetic resonance imaging (MRI) has potential value in distinguishing these 2 outcomes. The current meta-analysis examined the diagnostic accuracy of diffusion MRI with the apparent diffusion coefficient (ADC) in the differentiation of glioma recurrence from PSP.

METHOD

PubMed, Embase, Cochrane Library, and Chinese Biomedical databases were reviewed to identify studies that fulfilled our inclusion/exclusion criteria and were published on or before May 5, 2019. Threshold effects; heterogeneity; pooled sensitivity (SENS), specificity, positive likelihood ratio, and negative likelihood ratio; and diagnostic odds ratio were calculated. The overall diagnostic usefulness of diffusion MRI-derived ADC values was assessed by calculating the area under the curve (AUC) following summary receiver operating characteristic (SROC) analysis.

RESULTS

Six eligible studies examined a total of 214 patients. Calculation of pooled values indicated the SENS was 0.95 (95% confidence interval [CI] = 0.89-0.98), specificity was 0.83 (95% CI = 0.72-0.91), positive likelihood ratio was 4.82 (95% CI = 2.93-7.93), negative likelihood ratio was 0.08 (95% CI = 0.04-0.17), and diagnostic odds ratio was 59.63 (95% CI = 22.63-157.37). The SROC AUC was 0.9322. Publication bias was not significant, and SENS analysis indicated the results were relatively stable.

CONCLUSIONS

Our meta-analysis indicated that diffusion MRI with quantitative ADC is an effective approach for differentiation of glioma recurrence from PSP, and can be used as an auxiliary tool to diagnose glioma progression.

Combined iron oxide nanoparticle ferumoxytol and gadolinium contrast enhanced MRI define glioblastoma pseudoprogression

BACKGROUND

Noninvasively differentiating therapy-induced pseudoprogression from recurrent disease in patients with glioblastoma is prospectively difficult due to the current lack of a biologically specific imaging metric. Ferumoxytol iron oxide nanoparticle MRI contrast characterizes innate immunity mediated neuroinflammation; therefore, we hypothesized that combined ferumoxytol and gadolinium enhanced MRI could serve as a biomarker of glioblastoma pseudoprogression.

METHODS

In this institutional review board-approved, retrospective study, we analyzed ferumoxytol and gadolinium contrast enhanced T1-weighted 3T MRI in 45 patients with glioblastoma over multiple clinical timepoints. Isocitrate dehydrogenase 1 (IDH-1) mutational status was characterized by exome sequencing. Sum of products diameter measurements were calculated according to Response Assessment in Neuro-Oncology criteria from both gadolinium and ferumoxytol enhanced sequences. Enhancement mismatch was calculated as the natural log of the ferumoxytol to gadolinium sum of products diameter ratio. Analysis of variance and Student's t-test assessed differences in mismatch ratios. P-value <0.05 indicated statistical significance.

RESULTS

With the development of pseudoprogression we observed a significantly elevated mismatch ratio compared with disease recurrence (P < 0.01) within IDH-1 wild type patients. Patients with IDH-1 mutation demonstrated significantly reduced mismatch ratio with the development of pseudoprogression compared with disease recurrence (P < 0.01). Receiver operator curve analysis demonstrated 100% sensitivity and specificity for the use of mismatch ratios as a diagnostic biomarker of pseudoprogression.

CONCLUSION

Our study suggests that ferumoxytol to gadolinium contrast mismatch ratios are an MRI biomarker for the diagnosis of pseudoprogression in patients with glioblastoma. This may be due to the unique characterization of therapy-induced neuroinflammation.

One-day protocol for 18F-FDG and 13N-ammonia PET/CT with uptake decoupling score in differentiating untreated low-grade glioma from inflammation

PURPOSE

Accurate identification of low-grade gliomas (LGGs; World Health Organization grades I and II) and their differentiation from brain inflammation lesions (BILs) remains difficult; however, it is essential for treatment. This study assessed whether a one-day protocol for voxel-wise ¹⁸F-FDG and ¹³N-ammonia PET/CT with uptake decoupling analysis could differentiate LGGs from BILs.

MATERIALS AND METHODS

Twenty-eight patients with LGGs and 16 patients with BILs underwent ¹⁸F-FDG and ¹³N-ammonia PET/CT on the same day before any type of therapy. The decoupling score and tumor-to-normal tissue (T/N) ratio of ¹⁸F-FDG and ¹³N-ammonia were calculated at each location. Student's t-test was used to compare values, and ROC curve analysis was used to establish a cut-off value for the T/N ratio and decoupling score. Area under the curve (AUC) was calculated to evaluate differential efficacy.

RESULTS

Significant differences were observed in ¹³N-ammonia T/N ratio (p=0.018) and decoupling score (p=0.003) between LGGs and BILs; however, the ¹⁸F-FDG T/N ratio did not show any differences (p=0.413). Optimal cut-off values for ¹⁸F-FDG T/N ratio, ¹³N-ammonia T/N ratio, and decoupling score were 0.73, 0.97, and 2.31, respectively, with corresponding AUCs of 0.48, 0.68, and 0.77. The respective sensitivity, specificity, and accuracy parameters using these cut-off values were 53.6%, 62.5%, and 56.8%, respectively, for ¹⁸F-FDG; 50.0%, 75.0%, and 59.1%, respectively, for ¹³N-ammonia; and 60.7%, 93.8%, and 72.7%, respectively, for decoupling score.

CONCLUSIONS

¹⁸F-FDG/¹³N-ammonia uptake decoupling score can be used to discriminate between LGGs and BILs. Use of a decoupling map of these two tracers can improve visual analysis and diagnostic accuracy.

Metabolic response patterns in brain microdialysis fluids and serum during interstitial cisplatin treatment of high-grade glioma

Background

High-grade gliomas are associated with poor prognosis. Tumour heterogeneity and invasiveness create challenges for effective treatment and use of systemically administrated drugs. Furthermore, lack of functional predictive response-assays based on drug efficacy complicates evaluation of early treatment responses.

Methods

We used microdialysis to deliver cisplatin into the tumour and to monitor levels of metabolic compounds present in the tumour and non-malignant brain tissue adjacent to tumour, before and during treatment. In parallel, we collected serum samples and used multivariate statistics to analyse the metabolic effects.

Results

We found distinct metabolic patterns in the extracellular fluids from tumour compared to non-malignant brain tissue, including high concentrations of a wide range of amino acids, amino acid derivatives and reduced levels of monosaccharides and purine nucleosides. We found that locoregional cisplatin delivery had a strong metabolic effect at the tumour site, resulting in substantial release of glutamic acid, phosphate, and spermidine and a reduction of cysteine levels. In addition, patients with long-time survival displayed different treatment response patterns in both tumour and serum. Longer survival was associated with low tumour levels of lactic acid, glyceric acid, ketoses, creatinine and cysteine. Patients with longer survival displayed lower serum levels of ketohexoses, fatty acid methyl esters, glycerol-3-phosphate and alpha-tocopherol, while elevated phosphate levels were seen in both tumour and serum during treatment.

Conclusion

We highlight distinct metabolic patterns associated with high-grade tumour metabolism, and responses to cytotoxic cisplatin treatment.

18F-Fluciclovine PET/CT in Suspected Residual or Recurrent High-Grade Glioma

PURPOSE

To retrospectively investigate the uptake of F-fluciclovine on PET/CT in patients with suspected recurrent high-grade glioma (HGG).

METHODS

Twenty-one patients were included. The standard of truth was histopathologic interpretation if available. When histopathology was not available or rebiopsy did not show signs of malignancy, clinical follow-up including MRI and clinical outcome was considered the standard of truth.

RESULTS

All 21 patients met the reference standard of either histopathologic proof of HGG recurrence (n = 10) or disease progression clinically and with tumor growth corresponding to the primary tumor sites on follow-up MRI (n = 11). Median time from PET/CT to death was 5 months (range, 1-20 months). Median time from primary diagnosis to death was 14.5 months (range, 6 to >400). Average SUVmax of the lesions was 8.3 ± 5.3 (SD) and 0.34 ± 0.13 for normal brain tissue. Median lesion-to-background ratio was 21.6 (range, 3.1-84.4). In 4 patients, F-fluciclovine PET/CT detected small satellite tumors that had not been reported on MR.

CONCLUSIONS

The uptake of F-fluciclovine in clinically and/or histopathologically confirmed recurrent HGG is high compared with the uptake reported for other amino acid PET tracers. Because of the high tumor uptake and thus high tracer contrast, small satellite tumors with a diameter below usual reported PET spatial resolution and not reported on MRI were detected in 4 patients. As no patients with confirmed treatment-related changes were included, we cannot as of yet ascertain the ability of F-fluciclovine PET to discriminate between recurrent HGG and treatment-related changes, for example, pseudoprogression and radionecrosis.

MRI combined with PET-CT of different tracers to improve the accuracy of glioma diagnosis: a systematic review and meta-analysis

Based on studies focusing on positron emission tomography (PET)-computed tomography (CT) combined with magnetic resonance imaging (MRI) in the diagnosis of glioma, we conducted a systematic review and meta-analysis evaluating the pros and cons and the accuracy of different examinations. PubMed and Cochrane Library were searched. The search was conducted until April 2017. Two reviewers independently conducted the literature search according to the criteria set initially. Based on the exclusion criteria, 15 articles are included in this study. Of all studies that used MRI examination, there are five involving 18F-fluorodeoxyglucose-PET, five involving 11C-methionine-PET, five involving 18F-fluoro-ethyl-tyrosine-PET, and three involving 18F-fluorothymidine-PET. Due to the limitations such as lack of data, small sample size, and unrepresentative studies, we use a non-quantitative methodology. MRI examination can provide the anatomy information of glioma more clearly. PET-CT examinations based on tumor metabolism using different tracers have more advantages in determining the degree of glioma malignancy and boundaries. However, information provided by PET-CT of different tracers is not the same. With respect to the novel hybrid MRI/PET examination equipment proposed in recent years, the combination of MRI and PET-CT can definitively improve the diagnostic accuracy of glioma.

Institutional review of glial tumors treated with chemotherapy: the first description of PCV-related pseudoprogression

BACKGROUND

Pseudoprogression refers to areas of enhancement on MRI postadjuvant chemoradiation that arise as a result of treatment-related effects. Pseudoprogression has been well described with temozolomide-based chemoradiation but has not been studied in the setting of procarbazine, lomustine, and vincristine (PCV) chemotherapy. We reviewed patients treated with PCV to investigate the occurrence of pseudoprogression.

METHODS

Adults diagnosed with World Health Organization grade II or III gliomas between 2010 and 2015 and treated with PCV or temozolomide were identified. Patient, tumor, treatment, and MRI data were retrospectively collected and analyzed. Pseudoprogression was defined as new enhancement seen on MRI within 6 months of completion of adjuvant radiotherapy or concurrent chemoradiation, which improved or remained stable on subsequent scans without therapeutic intervention. If MRI showed areas of new enhancement outside the 6-month post-treatment window, which resolved or remained stable without treatment, or in patients who did not receive adjuvant treatment, it was referred to as "atypical pseudoprogression."

RESULTS

Fifty-seven patients were identified. Nine (16%) patients were identified as having pseudoprogression on MRI. Two (4%) of these patients were treated with PCV and 7 (12%) were treated with temozolomide. Seventeen (30%) patients had atypical pseudoprogression: 8 (14%) treated with temozolomide, 8 (14%) treated with PCV, and 1 (2%) treated with both types of chemotherapy.

CONCLUSIONS

We describe the first 2 cases of PCV-related pseudoprogression and 17 cases of atypical pseudoprogression. As the re-emergence of adjuvant PCV occurs in clinical practice, the occurrence of classical and atypical pseudoprogression could have a significant impact on clinical decision making.

The role of 13N-ammonia in the differential diagnosis of gliomas and brain inflammatory lesions

OBJECTIVE

To investigate the utility of ¹³N-ammonia PET/CT imaging in the differential diagnosis of gliomas and brain inflammations.

METHODS

¹³N-ammonia PET/CT imaging data of 77 patients with gliomas and 34 patients with brain inflammations were retrospectively analyzed. No patients received any treatment before ¹³N-ammonia imaging. All the patients were diagnosed by stereotactic biopsy or clinical follow-up. Visual and semi-quantitative analysis was performed to analyze the results of ¹³N-ammonia imaging. Finally, the uptake ratios of each lesion were calculated and its differences among different groups were tested with one-way ANOVA.

RESULTS

29.4% inflammations, 51.6% low-grade gliomas and 91.3% high-grade gliomas were positive by visual analysis in ¹³N-ammonia imaging. The sensitivity, specificity and accuracy for the diagnosis of gliomas were 75.3%, 55.8% and 67.8%, respectively. As for semi-quantitative analysis, the T/G ratios of inflammatory lesions, low-grade gliomas and high-grade gliomas were 0.88 ± 0.24, 1.04 ± 0.43 and 1.43 ± 0.49, respectively. One-way ANOVA revealed that the T/G ratios of high-grade gliomas were significantly higher than those of low-grade gliomas and inflammations (P < 0.05), but there was no statistical difference between low-grade gliomas and inflammations (P = 0.118). Among the inflammatory lesions, T/G ratios were not statistically different between infectious and demyelinating lesions (P > 0.05). ROC curve analysis showed that the optimal cut-off value of T/G ratio in distinguishing gliomas from inflammations was 1.21 with the AUC 0.78. The sensitivity, specificity, accuracy, PPV and NPV were 52.9%, 94.4%, 65.3%, 95.7% and 45.9%, respectively. ROC curve analysis showed that the optimal cut-off value of T/G ratio in distinguishing high-grade gliomas from low-grade gliomas was 1.06 with the AUC 0.78. The sensitivity, specificity, accuracy, PPV and NPV were 81.5%, 67.7%, 76.5%, 81.5% and 67.7%, respectively. ROC curve analysis showed that the optimal cut-off value of T/G ratio in distinguishing high-grade gliomas from low-grade gliomas and inflammations was 1.19 with the AUC 0.84. The sensitivity, specificity, accuracy, PPV and NPV were 70.4%, 85.1%, 78.5%, 79.2% and 78.1%, respectively.

CONCLUSIONS

¹³N-ammonia imaging is effective in distinguishing high-grade gliomas from low-grade gliomas and inflammations, but its role in the differential diagnosis of low-grade gliomas and brain inflammatory lesions is limited, and the accuracy needs to be improved.

MicroRNA-20a Regulates Glioma Cell Proliferation, Invasion, and Apoptosis by Targeting CUGBP Elav-Like Family Member 2

OBJECTIVE

MicroRNAs (miRNAs) are a class of small noncoding RNAs that play important roles in tumor development and progression. miR-20a acts as an oncogene in many cancers; however, the underlying role of miR-20a in human glioma remains unknown.

METHODS

Glioma tissue samples were obtained from 32 patients with primary glioma who had undergone surgery at the First Affiliated Hospital of Sun Yat-sen University (Guangzhou, China). Twenty-two normal brain tissue samples used as controls were obtained by internal decompression in patients who had undergone surgery for cerebral injury and cerebral hemorrhage at the same hospital.

RESULTS

Quantitative reverse transcription polymerase chain reaction showed upregulation of miR-20a in glioma tissues and cell lines compared with normal brain tissue and normal human astrocytes. Functional assays showed that miR-20a promotes proliferation and invasion and inhibits apoptosis in glioma cells. The bioinformatic analysis showed that CELF2 (CUGBP Elav-like family member 2) is a direct target gene of miR-20a, which was confirmed using a luciferase reporter assay. Downregulation of CELF2 reversed the effects of inhibiting miR-20a expression.

CONCLUSIONS

Collectively, these results suggest a critical role for miR-20a in glioma cell apoptosis, proliferation, and invasion via the direct targeting of CELF2 and indicate its potential application in cancer therapy.

Adult IDH wild-type lower-grade gliomas should be further stratified

Background

Astrocytoma of the isocitrate dehydrogenase (IDH) wild-type gene is described as a provisional entity within the new World Health Organization (WHO) classification. Some groups believe that IDH wild-type lower-grade gliomas, when interrogated for other biomarkers, will mostly turn out to be glioblastoma. We hypothesize that not all IDH wild-type lower-grade gliomas have very poor outcomes and the group could be substratified prognostically.

Methods

Seven hundred and eighteen adult WHO grades II and III patients with gliomas from our hospitals were re-reviewed and tested for IDH1/2 mutations. One hundred and sixty-six patients with IDH wild-type cases were identified for further studies, and EGFR and MYB amplifications, mutations of histone H3F3A, TERT promoter (TERTp), and BRAF were examined.

Results

EGFR amplification, BRAF, and H3F3A mutations were observed in 13.8%, 6.9%, and 9.5% of patients, respectively, in a mutually exclusive pattern in IDH wild-type lower-grade gliomas. TERTp mutations were detected in 26.8% of cases. Favorable outcome was observed in patients with young age, oligodendroglial phenotype, and grade II histology. Independent adverse prognostic values of older age, nontotal resection, grade III histology, EGFR amplification, and H3F3A mutation were confirmed by multivariable analysis. Tumors were further classified into "molecularly" high grade (harboring EGFR, H3F3A, or TERTp) (median overall survival = 1.23 y) and lower grade (lacking all of the 3) (median overall survival = 7.63 y) with independent prognostic relevance. The most favorable survival was noted in molecularly lower-grade gliomas with MYB amplification.

Conclusion

Adult IDH wild-type lower-grade gliomas are prognostically heterogeneous and do not have uniformly poor prognosis. Clinical information and additional markers, including MYB, EGFR, TERTp, and H3F3A, should be examined to delineate discrete favorable and unfavorable prognostic groups.

B7-H6 expression is induced by lipopolysaccharide and facilitates cancer invasion and metastasis in human gliomas

Although great progress has been made in treatment regimens, gliomas are still incurable and the 5-year survival remains poor. Studies focusing on molecules that regulate tumorigenesis or tumor immunity may provide potential therapeutic strategies for patients with glioma. B7-H6 is selectively expressed in tumor cells and plays vital roles in host immune responses. In this study, we demonstrated that B7-H6 was expressed in glioma cell lines, including CRT, U251, SHG-44, SF-295, TG-905 and U373, and tumor tissues isolated from glioma patients. Moreover, the expression levels of B7-H6 were significantly correlated with glioma grade. Previous studies reported that inflammatory mediators and cytokines induced the expression of B7 family members including programmed death-ligand 1, B7-H2 and B7-H4. Therefore, we explored the regulation of B7-H6 expression in gliomas and showed that lipopolysaccharide induced the expression of B7-H6 in glioma cells. To further analyze the roles of B7-H6 in gliomas, the expression of B7-H6 in glioma cells was knocked down. The results of cell counting kit-8, colony formation, wound healing, and transwell migration and invasion assays demonstrated that the proliferation, migration and invasion of glioma cells were inhibited after knocking down B7-H6. To elucidate the specific mechanisms of B7-H6 function in cancer progression, we examined the expression levels of proteins involved in cell apoptosis, migration and invasion. We demonstrated that the expression levels of E-cadherin and Bcl-2 associated X protein increased, and the expression levels of vimentin, N-cadherin, matrix metalloproteinase-2, matrix metalloproteinase-9 and survivin decreased after knocking down B7-H6. In conclusion, B7-H6 plays important roles in glioma, and targeting B7-H6 may provide a novel therapeutic strategy for glioma patients.

Differential radiation response between normal astrocytes and glioma cells revealed by comparative transcriptome analysis

Normal astrocytes are more resistant to radiation than glioma cells. Radiation-resistant glioma cells and normal astrocytes usuallly share similar mechanisms of radioresistance. Investigation of the underlying mechanisms of differential radiation response between normal astrocytes and glioma cells is thus significant for improvement of glioma treatment. Here, we report on the differential radiation responses between normal astrocytes and glioma cells at the transcriptome level. Human astrocytes (HA) and U251 glioma cell lines were used as in vitro models. The transcriptome profiles of radiation-treated and nontreated HA and U251 cells were generated by next-generation sequencing. In total, 296 mRNAs and 224 lncRNAs in HA and 201 mRNAs and 107 lncRNAs in U251 were found to be differentially expressed after radiation treatment. Bioinformatics analyses indicated that radiation causes similar alterations in HA and U251 cells, while several key pathways involved in cancer development and radiation resistance, including P53, TGF-β, VEGF, Hippo and serotonergic synapse pathways, were oppositely regulated by radiation treatment, suggesting their important role in this process. Furthermore, we showed the critical role of Hippo/YAP signaling in radiation resistance of glioma cells. In summary, our findings revealed novel insights about differential responses between normal astrocytes and glioma cells. Our work suggested that YAP inhibitor could not be used in combination with radiation for glioma treatment.

Insular gliomas: a surgical reappraisal based on a systematic review of the literature

INTRODUCTION

Insular gliomas are heterogeneous lesions whose management presents multiple challenges for their tendency to affect young patients in good neurological and cognitive conditions, their deep anatomic location and proximity with critical functional and vascular structures. The appropriate management of insular gliomas requires a multidisciplinary evidence-centred teamwork grounded on the best anatomic, neurophysiological and oncological knowledge. The present study provides a reappraisal of the management of insular gliomas based on a systematic review of the literature with the aim of guiding clinicians in the management of such tumors.

EVIDENCE ACQUISITION

A systematic review of the literature from the Medline, Embase and Cochrane Central databases was performed. From 2006 to 2016, all articles meeting specific inclusion criteria were included.

EVIDENCE SYNTHESIS

The present work summarizes the most relevant evidence about insular gliomas management. The anatomy and physiology of the insula, the new WHO 2016 classification and clinico-radiological presentation of insular gliomas are reviewed. Surgical pearls of insular gliomas resection as well as oncologic and functional outcomes after insular gliomas treatment are discussed.

CONCLUSIONS

Management of insular gliomas remains challenging despite improvement in surgical and oncological techniques. However, the literature review supports a growing evidence that recent developments in the multidisciplinary care account for constant improvements of survival and quality of life.

Clinical Applications of Contrast-Enhanced Perfusion MRI Techniques in Gliomas: Recent Advances and Current Challenges

Gliomas possess complex and heterogeneous vasculatures with abnormal hemodynamics. Despite considerable advances in diagnostic and therapeutic techniques for improving tumor management and patient care in recent years, the prognosis of malignant gliomas remains dismal. Perfusion-weighted magnetic resonance imaging techniques that could noninvasively provide superior information on vascular functionality have attracted much attention for evaluating brain tumors. However, nonconsensus imaging protocols and postprocessing analysis among different institutions impede their integration into standard-of-care imaging in clinic. And there have been very few studies providing a comprehensive evidence-based and systematic summary. This review first outlines the status of glioma theranostics and tumor-associated vascular pathology and then presents an overview of the principles of dynamic contrast-enhanced MRI (DCE-MRI) and dynamic susceptibility contrast-MRI (DSC-MRI), with emphasis on their recent clinical applications in gliomas including tumor grading, identification of molecular characteristics, differentiation of glioma from other brain tumors, treatment response assessment, and predicting prognosis. Current challenges and future perspectives are also highlighted.