Molecular and clinical characterization of PD-L1 expression at transcriptional level via 976 samples of brain glioma

Research progress and challenges of the PD-1/PD-L1 axis in gliomas

The emergence of programmed death-1 (PD-1) and programmed death ligand 1 (PD-L1) immunosuppressants provides new therapeutic directions for various advanced malignant cancers. At present, PD-1/PD-L1 immunosuppressants have made significant progress in clinical trials of some gliomas, but PD-1/PD-L1 inhibitors have not yet shown convincing clinical efficacy in gliomas. This article summarizes the research progress of the PD-1 /PD-L1 pathway in gliomas through the following three aspects. It mainly includes the complex expression levels and regulatory mechanisms of PD-1/PD-L1 in the glioma microenvironment, the immune infiltration in glioma immunosuppressive microenvironment, and research progress on the application of PD-1/PD-L1 immunosuppressants in clinical treatment trials for gliomas. This will help to understand the current treatment progress and future research directions better.

Targeting drug resistance in glioblastoma (Review)

Glioblastoma (GBM) is the most common malignancy of the central nervous system in adults. The current standard of care includes surgery, radiation therapy, temozolomide; and tumor‑treating fields leads to dismal overall survival. There are far limited treatments upon recurrence. Therapies to date are ineffective as a result of several factors, including the presence of the blood‑brain barrier, blood tumor barrier, glioma stem‑like cells and genetic heterogeneity in GBM. In the present review, the potential mechanisms that lead to treatment resistance in GBM and the measures which have been taken so far to attempt to overcome the resistance were discussed. The complex biology of GBM and lack of comprehensive understanding of the development of therapeutic resistance in GBM demands discovery of novel antigens that are targetable and provide effective therapeutic strategies.

Analysis of KLRB1-Mediated Immunosuppressive Regulation in Adamantinomatous Craniopharyngioma

BACKGROUND

 Adamantinomatous craniopharyngioma (ACP) is the most common type of craniopharyngioma (CP). Under the current surgery and/or radiotherapy strategies, the survival rate is high, but the long-term quality of life is poor because of the relationship between the hypothalamic-pituitary axis and the tumor. Many studies had shown that endocrine deficiencies caused by craniopharyngiomas of the hypothalamic-pituitary axis persist throughout almost the entire life of the patients after surgery, requiring them to receive hormone replacement therapy. Thus, we need to explore new treatments to improve the prognosis of patients. In recent years, there are more and more studies on the immunotherapy of various tumors. However, due to the rarity of the disease, immunotherapy for ACP is rarely researched. The discovery of the tumor immune-suppressive checkpoint KLRB1 (killer cell lectinlike receptor B1), which encodes CD161, may provide a novel target for the treatment of ACP.

METHODS

 Data analysis of retrospective RNA sequencing was conducted in a cohort of 51 pediatric samples in the GSE94349 dataset, and the results were well validated in the GSE68015 dataset including 31 pediatric samples. We used R language as the main tool for statistical analysis and graphical work.

RESULTS

 Our research showed that KLRB1 was enriched in ACP. Additionally, the expression of KLRB1 was positively related to immune functions and most inflammatory responses of ACP. We found that most of the T lineage-related immune responses were positively correlated with KLRB1 expression, and KLRB1 played an important role in the activation of inflammatory processes.

CONCLUSIONS

 KLRB1 is a promising target for immunotherapeutic strategies.

The predictive value of E2F7 in immunotherapy efficacy for lung adenocarcinoma: An observational study

Lung adenocarcinoma (LUAD) is the most common pathological type of lung cancer. In recent years, immunotherapy has greatly changed the treatment pattern of advanced LUAD. However, only a small proportion of LUAD patients benefitted from immune checkpoint inhibitor therapy. There is an urgent need to develop a biomarker to predict immune therapy response. E2F7 has been shown to be closely related to immune cell infiltration and immune checkpoint expression in tumors. However, it is unclear whether the E2F7 expression is related to the immunotherapy efficacy in LUAD. Therefore, we conducted this study to investigate the clinical characteristics, function, and immunotherapy responsiveness of E2F7 expression, and to explore the potential of E2F7 as an immunotherapy response biomarker in LUAD. We analyzed the clinical characteristics and biological function of E2F7 expression based on data from the Cancer Genome Atlas and Gene Expression Omnibus database. In addition, we used single-cell sequencing data to analyze the immune regulatory effects of E2F7 in LUAD. Furthermore, we analyzed the immunotherapy response prediction ability of E2F7 expression based on the immunotherapy database. Compared to normal lung tissue, E2F7 was specifically overexpressed in LUAD, and its expression was associated with higher malignancy and poor efficacy. E2F7 high expression was an independent risk factor affecting the prognosis of LUAD. E2F7 was enriched in cell division and cell cycle functions. In addition, the expressions of immune checkpoints were correlated with the E2F7 expression. E2F7 was highly expressed in myeloid cells, and E2F7 highly expressed myeloid cells were associated with immune and inflammatory responses. Moreover, the expression level of E2F7 can effectively distinguish different immune therapy responses in LUAD patients. E2F7 was upregulated in LUAD, and high expression of E2F7 was associated with higher malignancy and poor efficacy. E2F7 high expression was an independent risk factor affecting the prognosis of LUAD. Moreover, E2F7 may exert its immunosuppressive effect by affecting the function of myeloid cells. These results indicated the potential role of E2F7 as a biomarker for predicting LUAD immunotherapy responses.

mRNA markers for survival prediction in glioblastoma multiforme patients: a systematic review with bioinformatic analyses

BACKGROUND

Glioblastoma multiforme (GBM) is a type of fast-growing brain glioma associated with a very poor prognosis. This study aims to identify key genes whose expression is associated with the overall survival (OS) in patients with GBM.

METHODS

A systematic review was performed using PubMed, Scopus, Cochrane, and Web of Science up to Journey 2024. Two researchers independently extracted the data and assessed the study quality according to the New Castle Ottawa scale (NOS). The genes whose expression was found to be associated with survival were identified and considered in a subsequent bioinformatic study. The products of these genes were also analyzed considering protein-protein interaction (PPI) relationship analysis using STRING. Additionally, the most important genes associated with GBM patients' survival were also identified using the Cytoscape 3.9.0 software. For final validation, GEPIA and CGGA (mRNAseq_325 and mRNAseq_693) databases were used to conduct OS analyses. Gene set enrichment analysis was performed with GO Biological Process 2023.

RESULTS

From an initial search of 4104 articles, 255 studies were included from 24 countries. Studies described 613 unique genes whose mRNAs were significantly associated with OS in GBM patients, of which 107 were described in 2 or more studies. Based on the NOS, 131 studies were of high quality, while 124 were considered as low-quality studies. According to the PPI network, 31 key target genes were identified. Pathway analysis revealed five hub genes (IL6, NOTCH1, TGFB1, EGFR, and KDR). However, in the validation study, only, the FN1 gene was significant in three cohorts.

CONCLUSION

We successfully identified the most important 31 genes whose products may be considered as potential prognosis biomarkers as well as candidate target genes for innovative therapy of GBM tumors.

Integrative analysis of the cuproptosis-related gene ATP7B in the prognosis and immune infiltration of IDH1 wild-type glioma

Glioma is the most common malignant tumor in the brain and the central nervous system with a poor prognosis, and wild-type isocitrate dehydrogenase (IDH) glioma indicates a worse prognosis. Cuproptosis is a recently discovered form of cell death regulated by copper-dependent mitochondrial respiration. However, the effect of cuproptosis on tumor prognosis and immune infiltration is not clear. In this research, we analyzed of public databases to show the correlation between cuproptosis-related genes and the prognosis of IDH1 wild-type glioma. Nine out of 12 genes were upregulated in IDH1 wild-type glioma patients, and 6 genes were significantly associated with overall survival (OS), while 5 genes were associated with progression-free survival (PFS). Then, we constructed a prognostic cuproptosis-related gene signature for IDH1 wild-type glioma patients. ATP7B was considered an independent prognostic indicator, and a low expression level of ATP7B was related to a shorter period of OS and PFS. Moreover, downregulation of ATP7B was correlated not only with the infiltration of activated NK cells, CD8 + T cells and M2 macrophages; but also with high expression of immune checkpoint genes and tumor mutation burden (TMB). In the IDH1 wild-type glioma tissues we collected, our data also confirmed that high tumor grade was accompanied by low expression of ATP7B and high expression of PD-L1, which was associated with increasing infiltration of CD8 + immune cells. In conclusion, our research constructed a prognostic cuproptosis-related gene signature model to predict the prognosis of IDH1 wild-type glioma. ATP7B is deemed to be a potential prognostic indicator and novel immunotherapy biomarker for IDH1 wild-type glioma patients.

Comprehensive analysis of CYBB as a prognostic marker and therapeutic target in glioma: A bioinformatics approach

Background

In the central nervous system, glioma is the most common malignant tumor, and patients have a poor prognosis. Identification of novel marker genes and establishment of prognostic models are important for early diagnosis and prognosis determination.

Methods

Download glioma data from the CGGA and TCG databases. Application of bioinformatics to analyze the impact of CYBB on the clinicopathological characteristics, immunological features and prognosis of gliomas. Using single-cell sequencing data from 7 glioblastoma patients in the CGGA database, the role of CYBB in the tumor microenvironment was analyzed. In addition, a prognostic model was constructed based on CYBB high and low differentially expressed genes and mitochondrial genes.

Results

The expression of CYBB is closely related to various clinical features, immune cell infiltration level, immune checkpoint and survival time of patients. A 10-gene prediction model was constructed based on the differentially expressed genes of low and high CYBB and mitochondria-related genes. Glioma patients with higher risk scores had significantly lower survival probabilities. Receiver operating characteristic curves and nomograms were plotted over time to show the predictive accuracy and predictive value of the 10-gene prognostic model.

Conclusions

Our study shows that CYBB is strongly correlated with clinical characteristics features and prognosis of glioma patients, and can be used as a potential therapeutic target. Prognostic models based on CYBB and mitochondrial genes have good performance in predicting prognosis of glioma patients.

Treatment advances in high-grade gliomas

High-grade gliomas (HGG) pose significant challenges in modern tumour therapy due to the distinct biological properties and limitations of the blood-brain barrier. This review discusses recent advancements in HGG treatment, particularly in the context of immunotherapy and cellular therapy. Initially, treatment strategies focus on targeting tumour cells guided by the molecular characteristics of various gliomas, encompassing chemotherapy, radiotherapy and targeted therapy for enhanced precision. Additionally, technological enhancements are augmenting traditional treatment modalities. Furthermore, immunotherapy, emphasising comprehensive tumour management, has gained widespread attention. Immune checkpoint inhibitors, vaccines and CAR-T cells exhibit promising efficacy against recurrent HGG. Moreover, emerging therapies such as tumour treating fields (TTFields) offer additional treatment avenues for patients with HGG. The combination of diverse treatments holds promise for improving the prognosis of HGG, particularly in cases of recurrence.

Proneural-mesenchymal antagonism dominates the patterns of phenotypic heterogeneity in glioblastoma

The aggressive nature of glioblastoma (GBM) - one of the deadliest forms of brain tumors - is majorly attributed to underlying phenotypic heterogeneity. Early attempts to classify this heterogeneity at a transcriptomic level in TCGA GBM cohort proposed the existence of four distinct molecular subtypes: Proneural, Neural, Classical, and Mesenchymal. Further, a single-cell RNA sequencing (scRNA-seq) analysis of primary tumors also reported similar four subtypes mimicking neurodevelopmental lineages. However, it remains unclear whether these four subtypes identified via bulk and single-cell transcriptomics are mutually exclusive or not. Here, we perform pairwise correlations among individual genes and gene signatures corresponding to these proposed subtypes and show that the subtypes are not distinctly mutually antagonistic in either TCGA or scRNA-seq data. We observed that the proneural (or neural progenitor-like)-mesenchymal axis is the most prominent antagonistic pair, with the other two subtypes lying on this spectrum. These results are reinforced through a meta-analysis of over 100 single-cell and bulk transcriptomic datasets as well as in terms of functional association with metabolic switching, cell cycle, and immune evasion pathways. Finally, this proneural-mesenchymal antagonistic trend percolates to the association of relevant transcription factors with patient survival. These results suggest rethinking GBM phenotypic characterization for more effective therapeutic targeting efforts.

TGIF2 is a potential biomarker for diagnosis and prognosis of glioma

Background

TGFB-induced factor homeobox 2 (TGIF2), a member of the Three-Amino-acid-Loop-Extension (TALE) superfamily, has been implicated in various malignant tumors. However, its prognostic significance in glioma, impact on tumor immune infiltration, and underlying mechanisms in glioma development remain elusive.

Methods

The expression of TGIF2 in various human normal tissues, normal brain tissues, and gliomas was investigated using HPA, TCGA, GTEx, and GEO databases. The study employed several approaches, including Kaplan-Meier analysis, ROC analysis, logistic regression, Cox regression, GO analysis, KEGG analysis, and GSEA, to explore the relationship between TGIF2 expression and clinicopathologic features, prognostic value, and potential biological functions in glioma patients. The impact of TGIF2 on tumor immune infiltration was assessed through Estimate, ssGSEA, and Spearman analysis. Genes coexpressed with TGIF2 were identified, and the protein-protein interaction (PPI) network of these coexpressed genes were constructed using the STRING database and Cytoscape software. Hub genes were identified using CytoHubba plugin, and their clinical predictive value was explored. Furthermore, in vitro experiments were performed by knocking down and knocking out TGIF2 using siRNA and CRISPR/Cas9 gene editing, and the role of TGIF2 in glioma cell invasion and migration was analyzed using transwell assay, scratch wound-healing assay, RT-qPCR, and Western blot.

Results

TGIF2 mRNA was found to be upregulated in 21 cancers, including glioma. High expression of TGIF2 was associated with malignant phenotypes and poor prognosis in glioma patients, indicating its potential as an independent prognostic factor. Furthermore, elevated TGIF2 expression positively correlated with cell cycle regulation, DNA synthesis and repair, extracellular matrix (ECM) components, immune response, and several signaling pathways that promote tumor progression. TGIF2 showed correlations with Th2 cells, macrophages, and various immunoregulatory genes. The hub genes coexpressed with TGIF2 demonstrated significant predictive value. Additionally, in vitro experiments revealed that knockdown and knockout of TGIF2 inhibited glioma cell invasion, migration and suppressed the epithelial-mesenchymal transition (EMT) phenotype.

Conclusion

TGIF2 emerges as a potential biomarker for glioma, possibly linked to tumor immune infiltration and EMT.

Current state of immune checkpoints therapy for glioblastoma

Glioblastoma (GBM), one of the most aggressive forms of brain cancer, has limited treatment options. Recent years have witnessed the remarkable success of checkpoint inhibitor immunotherapy across various cancer types. Against this backdrop, several clinical trials investigating checkpoint inhibitors for GBM are underway in multiple countries. Furthermore, the integration of immunotherapy with traditional treatment approaches is now emerging as a highly promising strategy. This review summarizes the latest advancements in checkpoint inhibitor immunotherapy for GBM treatment. We provide a concise yet comprehensive overview of current GBM immunotherapy options. Additionally, this review underscores combination strategies and potential biomarkers for predicting response and resistance in GBM immunotherapies.

Identification of molecular subtypes and a risk model based on inflammation-related genes in patients with low grade glioma

Lower grade gliomas (LGGs) exhibit invasiveness and heterogeneity as distinguishing features. The outcome of patients with LGG differs greatly. Recently, more and more studies have suggested that infiltrating inflammation cells and inflammation-related genes (IRGs) play an essential role in tumorigenesis, prognosis, and treatment responses. Nevertheless, the role of IRGs in LGG remains unclear. In The Cancer Genome Atlas (TCGA) cohort, we conducted a thorough examination of the predictive significance of IRGs and identified 245 IRGs that correlated with the clinical prognosis of individuals diagnosed with LGG. Based on unsupervised cluster analysis, we identified two inflammation-associated molecular clusters, which presented different tumor immune microenvironments, tumorigenesis scores, and tumor stemness indices. Furthermore, a prognostic risk model including ten prognostic IRGs (ADRB2, CD274, CXCL12, IL12B, NFE2L2, PRF1, SFTPC, TBX21, TNFRSF11B, and TTR) was constructed. The survival analysis indicated that the IRGs risk model independently predicted the prognosis of patients with LGG, which was validated in an independent LGG cohort. Moreover, the risk model significantly correlated with the infiltrative level of immune cells, tumor mutation burden, expression of HLA and immune checkpoint genes, tumorigenesis scores, and tumor stemness indices in LGG. Additionally, we found that our risk model could predict the chemotherapy response of some drugs in patients with LGG. This study may enhance the advancement of personalized therapy and improve outcomes of LGG.

Network pharmacology-based strategy to investigate the effect and mechanism of α-solanine against glioma

BACKGROUND

An anti-tumour activity has been demonstrated for α-solanine, a bioactive compound extracted from the traditional Chinese herb Solanum nigrum L. However, its efficacy in the treatment of gliomas and the underlying mechanisms remain unclear. The aim of this study was to investigate the inhibitory effects of α-solanine on glioma and elucidate its mechanisms and targets using network pharmacology, molecular docking, and molecular biology experiments.

METHODS

Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) was utilized to predict the potential targets of α-solanine. GeneCards was used to gather glioma-related targets, and the STRING online database was used to analyze protein-protein interaction (PPI) networks for the shared targets. Hub genes were identified from the resulting PPI network and further investigated using Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Additionally, prognostic and gene set enrichment analyses (GSEA) were carried out to identify potential therapeutic targets and their underlying mechanisms of action in relation to the prognosis of gliomas. In vitro experiments were conducted to verify the findings from the network pharmacology analysis.

RESULTS

A total of 289 α-solanine targets and 1149 glioma-related targets were screened, of which 78 were common targets. 11 hub genes were obtained, including SRC, HRAS, HSP90AA1, IGF1, MAPK1, MAPK14, KDR, STAT1, JAK2, MAP2K1, and IGF1R. The GO and KEGG pathway analyses unveiled that α-solanine was strongly associated with several signaling pathways, including positive regulation of MAP kinase activity and PI3K-Akt. Moreover, α-solanine (10 µM and 15 µM) inhibited the proliferation and migration but promoted the apoptosis of glioma cells. Finally, STAT1 was identified as a potential mediator of the effect of α-solanine on glioma prognosis.

CONCLUSION

α-Solanine can inhibit the proliferation and migration of gliomas by regulating multiple targets and signalling pathways. These findings lay the foundation for the creation of innovative clinical anti-glioma agents.

CMTM6 as a potential therapy target is associated with immunological tumor microenvironment and can promote migration and invasion in pancreatic adenocarcinoma

CMTM6 has been connected to the development of several malignancies. However, it is still unknown what function CMTM6 serves in pancreatic adenocarcinoma (PAAD). We obtained RNA sequencing information of PAAD from public datasets and predicted statistical significance of CMTM6 survival in accordance with Kaplan-Meier curves. Gene set enrichment assessment (GSEA) was employed to analyze changes in pathways. Then, we systematically investigated the association involving CMTM6 and the immunological traits within the tumor microenvironment (TME) of PAAD, including immune pathways, immunomodulators, immune infiltrating cells, inflammatory activities, and immunotherapy response prediction. To demonstrate the biologically malignant properties of CMTM6 expression, the Cell Counting Kit-8, transwell experiments, colony formation, and wound healing were utilized. Upregulated CMTM6 expression was revealed within PAAD tissues, which was associated with more frequent somatic mutations and worse survival outcomes. Specifically, CMTM6 expression represented stronger immune infiltration, inflammatory activity, and better immunotherapeutic response in TME. Functional studies revealed that CMTM6 promoted the ability to proliferate, migrate, and invade. Additionally, CMTM6 and PD-L1 had a positive relationship, and CMTM6 can co-immunocoprecipitate with PD-L1 protein in pancreatic cell lines. CMTM6 overexpression shapes the inflammatory TME with a strong immune response. These findings support that CMTM6 is an immunotherapeutic target with promising effect to treat PAAD.

AHR, a novel inhibitory immune checkpoint receptor, is a potential therapeutic target for chemoresistant glioblastoma

PURPOSE

This study aims to elucidate the mechanism underlying temozolomide resistance in patients with MGMT promoter hypomethylated glioblastoma, which is correlated with poor prognosis. The objective is to identify therapeutic targets and drugs suitable for temozolomide-resistant glioblastoma patients using big data analysis.

METHODS

In this retrospective study, transcriptome sequencing data from 457 glioblastoma patients, multi-omics data, and single-cell sequencing data were employed to assess the expression pattern, prognostic value, and biological functions of AHR in glioblastoma. The HERB database was utilized to screen for AHR-targeted drugs for glioblastoma treatment. Validation of our findings was conducted using multiplex immunofluorescence staining of clinical samples and T cells and tumor cells co-culture models.

RESULTS

Our findings demonstrated that patients with MGMT promoter unmethylation did not benefit from postoperative temozolomide chemotherapy due to resistance arising from DNA repair function and tumor immune response. AHR was found to be expressed in immune cells and exhibited an immunomodulatory role in glioblastoma with MGMT promoter unmethylation. AHR was identified as a potential novel inhibitory immune checkpoint receptor, serving as a therapeutic target for temozolomide-resistant glioblastoma. Furthermore, targeting AHR with Semen aesculi markedly enhanced the cytotoxic effect of T cells on glioma cells.

CONCLUSIONS

In addition to DNA repair function, the tumor immune response plays a pivotal role in temozolomide resistance of glioblastoma. Herbal compounds targeting AHR may offer an effective treatment for temozolomide-resistant glioblastoma.

Bradykinin B1 Receptor Affects Tumor-Associated Macrophage Activity and Glioblastoma Progression

Bradykinin is a small active peptide and is considered an inflammatory mediator in several pathological conditions. Bradykinin exerts its effects by coupling to its receptors, including bradykinin B1 (B1R) and bradykinin B2. B1R has been implicated in the development of various cancers. Our previous study reported that B1R promoted glioblastoma (GBM) development by supporting the migration and invasion of GBM cells. However, the mechanisms underlying the effects of B1R on tumor-associated macrophages (TAMs) and GBM progression remain unknown. Accordingly, to explore the regulatory effects of B1R overexpression (OE) in GBM on tumor-associated immune cells and tumor progression, we constructed a B1R wild-type plasmid and developed a B1R OE model. The results reveal that B1R OE in GBM promoted the expression of ICAM-1 and VCAM-1-cell adhesion molecules-in GBM. Moreover, B1R OE enhanced GBM cell migration ability and monocyte attachment. B1R also regulated the production of the protumorigenic cytokines and chemokines IL-6, IL-8, CXCL11, and CCL5 in GBM, which contributed to tumor progression. We additionally noted that B1R OE in GBM increased the expression of CD68 in TAMs. Furthermore, B1R OE reduced the level of reactive oxygen species in GBM cells by upregulating heme oxygenase-1, an endogenous antioxidant protein, thereby protecting GBM cells from oxidative stress. Notably, B1R OE upregulated the expression of programmed death-ligand 1 in both GBM cells and macrophages, thus providing resistance against T-cell response. B1R OE in GBM also promoted tumor growth and reduced survival rates in an intracranial xenograft mouse model. These results indicate that B1R expression in GBM promotes TAM activity and modulates GBM progression. Therefore, B1R could be an effective target for therapeutic methods in GBM.

Molecular and clinical characterization of PTRF in glioma via 1,022 samples

Polymerase I and transcript release factor (PTRF) plays a role in the regulation of gene expression and the release of RNA transcripts during transcription, which have been associated with various human diseases. However, the role of PTRF in glioma remains unclear. In this study, RNA sequencing (RNA-seq) data (n = 1022 cases) and whole-exome sequencing (WES) data (n = 286 cases) were used to characterize the PTRF expression features. Gene ontology (GO) functional enrichment analysis was used to assess the biological implication of changes in PTRF expression. As a result, the expression of PTRF was associated with malignant progression in gliomas. Meanwhile, somatic mutational profiles and copy number variations (CNV) revealed the glioma subtypes classified by PTRF expression showed distinct genomic alteration. Furthermore, GO functional enrichment analysis suggested that PTRF expression was associated with cell migration and angiogenesis, particularly during an immune response. Survival analysis confirmed that a high expression of PTRF is associated with a poor prognosis. In summary, PTRF may be a valuable factor for the diagnosis and treatment target of glioma.

Advanced immunotherapies for glioblastoma: tumor neoantigen vaccines in combination with immunomodulators

Glial-origin brain tumors, including glioblastomas (GBM), have one of the worst prognoses due to their rapid and fatal progression. From an oncological point of view, advances in complete surgical resection fail to eliminate the entire tumor and the remaining cells allow a rapid recurrence, which does not respond to traditional therapeutic treatments. Here, we have reviewed new immunotherapy strategies in association with the knowledge of the immune micro-environment. To understand the best lines for the future, we address the advances in the design of neoantigen vaccines and possible new immune modulators. Recently, the efficacy and availability of vaccine development with different formulations, especially liposome plus mRNA vaccines, has been observed. We believe that the application of new strategies used with mRNA vaccines in combination with personalized medicine (guided by different omic's strategies) could give good results in glioma therapy. In addition, a large part of the possible advances in new immunotherapy strategies focused on GBM may be key improving current therapies of immune checkpoint inhibitors (ICI), given the fact that this type of tumor has been highly refractory to ICI.

Therapies for IDH-Mutant Gliomas

PURPOSE OF REVIEW

Isocitrate dehydrogenase (IDH) mutant gliomas are a distinct type of primary brain tumors with unique characteristics, behavior, and disease outcomes. This article provides a review of standard of care treatment options and innovative, therapeutic approaches that are currently under investigation for these tumors.

RECENT FINDINGS

Extensive pre-clinical data and a variety of clinical studies support targeting IDH mutations in glioma using different mechanisms, which include direct inhibition and immunotherapies that target metabolic and epigenomic vulnerabilities caused by these mutations. IDH mutations have been recognized as an oncogenic driver in gliomas for more than a decade and as a positive prognostic factor influencing the research for new therapeutic methods including IDH inhibitors, DNA repair inhibitors, and immunotherapy.

The Current Landscape of Immune Checkpoint Inhibitor Immunotherapy for Primary and Metastatic Brain Tumors

Antibodies against immune checkpoint inhibitors (ICIs) have revolutionized the treatment of multiple aggressive malignancies, including melanoma and non-small cell lung cancer. ICIs for the treatment of primary and metastatic brain tumors have been used with varying degrees of success. Here, we discuss the available evidence for the use of ICIs in the treatment of primary and metastatic brain tumors, highlighting challenges and opportunities for furthering this type of cancer immunotherapy in neuro-oncology.

Emerging hallmark of gliomas microenvironment in evading immunity: a basic concept

Background

Over the last decade, since clinical trials examining targeted therapeutics for gliomas have failed to demonstrate a meaningful increase in survival, the emphasis has recently been switched toward innovative techniques for modulating the immune response against tumors and their microenvironments (TME). Cancerous cells have eleven hallmarks which make it distinct from normal ones, among which is immune evasion. Immune evasion in glioblastoma helps it evade various treatment modalities.

Summary

Glioblastoma’s TME is composed of various array of cellular actors, ranging from peripherally derived immune cells to a variety of organ-resident specialized cell types. For example, the blood–brain barrier (BBB) serves as a selective barrier between the systemic circulation and the brain, which effectively separates it from other tissues. It is capable of blocking around 98% of molecules that transport different medications to the target tumor.

Objectives

The purpose of this paper is to offer a concise overview of fundamental immunology and how ‘clever’ gliomas avoid the immune system despite the discovery of immunotherapy for glioma.

Conclusions

Herein, we highlight the complex interplay of the tumor, the TME, and the nearby normal structures makes it difficult to grasp how to approach the tumor itself. Numerous researchers have found that the brain TME is a critical regulator of glioma growth and treatment efficacy.

Expression and Prognostic Value of CD80 and CD86 in the Tumor Microenvironment of Newly Diagnosed Glioblastoma

BACKGROUND

Strategies to modulate the tumor microenvironment (TME) have opened new therapeutic avenues with dramatic yet heterogeneous intertumoral efficacy in multiple cancers, including glioblastomas (GBMs). Therefore, investigating molecular actors of TME may help understand the interactions between tumor cells and TME. Immune checkpoint proteins such as a Cluster of Differentiation 80 (CD80) and CD86 are expressed on the surface of tumor cells and infiltrative tumor lymphocytes. However, their expression and prognostic value in GBM microenvironment are still unclear.

METHODS

In this study, we investigated, in a retrospective local discovery cohort and a validation TCGA dataset, expression of CD80 and CD86 at mRNA level and their prognostic significance in response to standard of care. Furthermore, CD80 and CD86 at the protein level were investigated in the discovery cohort.

RESULTS

Both CD80 and CD86 are expressed heterogeneously in the TME at mRNA and protein levels. In a univariate analysis, the mRNA expression of CD80 and CD86 was not significantly correlated with OS in both local OncoNeuroTek dataset and TCGA datasets. CD80 and CD86 mRNA high expression was significantly associated with shorter progression free survival (PFS) (p < 0.05). These findings were validated using the TCGA cohort; higher CD80 and CD86 expressions were correlated with shorter PFS (p < 0.05). In multivariate analysis, CD86 mRNA expression was an independent prognostic factor for PFS in the TCGA dataset only (p < 0.05).

CONCLUSION

CD86 could be used as a potential biomarker for the prognosis of GBM patients treated with immunotherapy; however, additional studies are needed to validate these findings.

Systematic analysis identifies REST as an oncogenic and immunological biomarker in glioma

The repressor element 1 silencing transcription factor (REST) has been proposed to function as a transcription factor to silence gene transcription by binding to repressor element 1 (RE1), a highly conserved DNA motif. The functions of REST in various tumors have been studied, but its role and correlation with immune cell infiltration remains uncertain in gliomas. REST expression was analyzed in datasets of The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) and validated by the Gene Expression Omnibus and Human Protein Atlas databases. The clinical prognosis of REST was evaluated by clinical survival data of TCGA cohort and validated by Chinese Glioma Genome Atlas cohort. MicroRNAs (miRNAs) contributing to REST overexpression in glioma were identified by a combination of a series of in silico analyses, including expression analysis, correlation analysis, and survival analysis. The correlations between immune cell infiltration level and REST expression were analyzed by TIMER2 and GEPIA2 tools. Enrichment analysis of REST was performed using STRING and Metascape tools. The expression and function of predicted upstream miRNAs at REST and their association with glioma malignancy and migration were also confirmed in glioma cell lines. REST was highly expressed and associated with poorer overall survival and disease-specific survival in glioma and some other tumors. MiR-105-5p and miR-9-5p were identified as the most potential upstream miRNAs of REST in glioma patient cohort and experiments in vitro. REST expression was positively correlated with infiltration of immune cells and the expression of immune checkpoints such as PD1/PD-L1 and CTLA-4 in glioma. Furthermore, histone deacetylase 1 (HDAC1) was a potential REST-related gene in glioma. Enrichment analysis of REST found chromatin organization and histone modification were the most significant enriched terms, and Hedgehog-Gli pathway might be involved in the effect of REST on the pathogenesis of glioma. Our study suggests REST to be an oncogenic gene and the biomarker of poor prognosis in glioma. High REST expression might affect the tumor microenvironment of glioma. More basic experiments and large clinical trials aimed at the carcinogenetic study of REST in glioma will be needed in the future.

Immunohistochemical Expression of PD-L1 and IDH1 with Detection of MGMT Promoter Methylation in Astrocytoma

OBJECTIVE

Programmed death ligand 1 (PD-L1) expression was suggested as a poor prognostic predictor for glioblastoma. While isocitrate dehydrogenase (IDH) has been linked to enhanced overall survival in glioma cells. In glioblastoma patients receiving treatment with alkylating drugs, the methylguanine-DNA methyltransferase (MGMT) promoter's methylation status has been discovered as a potent and distinct predictor of good survival. In this study, we aimed to investigate the expression rate of PD-L1, IDH1, and MGMT methylation in patients with different grades of  astrocytoma.

METHODS

The present retrospective study retrieved the data and archived paraffin blocks of 60 cases of astrocytoma. Immunohistochemical evaluation was done to assess the expressions of PD-L1 and IDH1, Methylation-specific-PCR was used to investigate the MGMT promoter.

RESULTS

This study included astrocytoma grade II 18% (11/60), grade III 22% (13/60), grade IV 60% (36 cases). PD-L1 expression was detected in 82% of all studied cases (49/60) while IDH1 mutant astrocytoma were 73% (44/60) & methylation was reported in 58.3% (35 cases). High grade astrocytoma showed highrer expression of PD-L1 & IDH1 but with insignificant correlation (p=0.989).

CONCLUSION

There is a relatively high expression of PD-L1 and IDH1 in patients with astrocytoma. More than half of the patients presented with MGMT promoter methylation. Further studies with larger sample size are required to investigate the association between these biomarkers and characteristics of patients with astrocytoma.

The immunosuppressive microenvironment and immunotherapy in human glioblastoma

Glioblastoma multiforme (GBM) is the most malignant intracranial tumor in adults, characterized by extensive infiltrative growth, high vascularization, and resistance to multiple therapeutic approaches. Among the many factors affecting the therapeutic effect, the immunosuppressive GBM microenvironment that is created by cells and associated molecules via complex mechanisms plays a particularly important role in facilitating evasion of the tumor from the immune response. Accumulating evidence is also revealing a close association of the gut microbiota with the challenges in the treatment of GBM. The gut microbiota establishes a connection with the central nervous system through bidirectional signals of the gut-brain axis, thus affecting the occurrence and development of GBM. In this review, we discuss the key immunosuppressive components in the tumor microenvironment, along with the regulatory mechanism of the gut microbiota involved in immunity and metabolism in the GBM microenvironment. Lastly, we concentrate on the immunotherapeutic strategies currently under investigation, which hold promise to overcome the hurdles of the immunosuppressive tumor microenvironment and improve the therapeutic outcome for patients with GBM.

Comprehensive characterization of TNFSF14/LIGHT with implications in prognosis and immunotherapy of human gliomas

Glioblastoma multiforme (GBM) is a common central neural system malignant tumor among adults. Alongside its microscopic spread, immunosuppression in the tumor microenvironment also induces its refractoriness, which makes immunotherapy for GBM particularly important. Unfortunately, traditional immune checkpoint inhibitors (ICIs) often show limited therapeutic effects in GBM clinical trials, and new therapeutic strategies or targets are urgently needed. TNFSF14/LIGHT is a novel immune checkpoint molecule that plays essential roles in both innate and acquired immunity. Despite recent advances in our understanding of the function of TNFSF14/LIGHT in a variety of cancer types, the clinical and immunological importance of TNFSF14/LIGHT in human gliomas has not been fully explained. Here, we employed a comprehensive in silico analysis with publicly available data to analyze the molecular and immune characteristics of TNFSF14/LIGHT to explore its feasibility as an immunotherapy target. Totally, 2215 glioma cases were enrolled in the current study. Immunohistochemistry staining based on patient tissues (n = 34) was performed for the validation. TNFSF14/LIGHT was expressed higher in higher-WHO-grade gliomas and mesenchymal subtypes, and it was sensitive as a prognostic marker in GBM and low-grade glioma (LGG). A nomogram prognostic model was established based on TNFSF14/LIGHT expression together with other risk factors. Additionally, Gene Ontology and pathway analysis revealed that TNFSF14/LIGHT participated in T-cell activities and inflammatory processes. Moreover, analysis based on the structure and interactions of TNFSF14/LIGHT revealed its mutation sites in tumors as well as crucial interacting proteins. Analysis of IMvigor210 indicated the role of TNFSF14/LIGHT in immunotherapy. Altogether, our results reveal an underlying role of TNFSF14/LIGHT as an immunotherapy target in GBM.

The prognostic significance of PD-L1 expression in patients with glioblastoma: A meta-analysis

Background

Glioblastoma (GBM) is a malignant brain tumor associated with high morbidity and mortality rates with a poor prognosis. In recent years, studies on prognostic markers such as programmed death ligand 1 (PD-L1) have increased; however, their conclusions remain controversial. Here, relevant literature was reviewed and a meta-analysis was performed to clarify the correlation between PD-L1 expression and overall survival (OS) in GBM.

Methods

The non-foundational literature on PD-L1 expression associated with OS in GBM up to February 2022 was searched in the PubMed, Metstr, Cochrane, and Web of Science databases. Literature was rigorously screened according to inclusion and exclusion criteria, the total hazard ratio (HR), and corresponding 95% confidence intervals (CIs).

Results

Calculating the combined HR value and corresponding 95% CI of HR=1.124 (95% CI: 1.047-1.201, P=0.000, I2 (I-squared)=48.8%), it was shown that PD-L1 expression was significantly associated with low OS in GBM patients. Although I2 = 48.8% < 50%, to make the results more credible, in the cutoff values ≥10% subgroup HR=1.37 (95% CI: 1.07-1.67, P=0.000, I2 = 0%), which was also the result found in the first meta-analysis. In contrast, in the cutoff value ≥5% subgroup HR=1.14 (95% CI: 0.98-1.30, P=0.000, I2 = 59.8%) and in the cutoff value median PD-L1 expression levels subgroup HR=1.05 (95% CI: 0.92-1.18, P=0.000, I2 = 0%), indicating that PD-L1 expression was not associated with low OS in GBM. Furthermore, in four studies, we found no significant correlation between PD-L1 expression and the progression-free survival of GBM (HR=1.14, 95% CI:0.40-1.88, P=0.03, I2 = 29.3%).

Conclusion

PD-L1 expression was significantly associated with low OS in GBM patients; however, this result needs to be interpreted with caution and requires a large, multicenter clinical study in patients with similar baseline data for further evaluation.

The Oncolytic Adenovirus XVir-N-31, in Combination with the Blockade of the PD-1/PD-L1 Axis, Conveys Abscopal Effects in a Humanized Glioblastoma Mouse Model

Glioblastoma (GBM) is an obligatory lethal brain tumor with a median survival, even with the best standard of care therapy, of less than 20 months. In light of this fact, the evaluation of new GBM treatment approaches such as oncolytic virotherapy (OVT) is urgently needed. Based on our preliminary preclinical data, the YB-1 dependent oncolytic adenovirus (OAV) XVir-N-31 represents a promising therapeutic agent to treat, in particular, therapy resistant GBM. Preclinical studies have shown that XVir-N-31 prolonged the survival of GBM bearing mice. Now using an immunohumanized mouse model, we examined the immunostimulatory effects of XVir-N-31 in comparison to the wildtype adenovirus (Ad-WT). Additionally, we combined OVT with the inhibition of immune checkpoint proteins by using XVir-N-31 in combination with nivolumab, or by using a derivate of XVir-N-31 that expresses a PD-L1 neutralizing antibody. Although in vitro cell killing was higher for Ad-WT, XVir-N-31 induced a much stronger immunogenic cell death that was further elevated by blocking PD-1 or PD-L1. In vivo, an intratumoral injection of XVir-N-31 increased tumor infiltrating lymphocytes (TILs) and NK cells significantly more than Ad-WT not only in the virus-injected tumors, but also in the untreated tumors growing in the contralateral hemisphere. This suggests that for an effective treatment of GBM, immune activating properties by OAVs seem to be of greater importance than their oncolytic capacity. Furthermore, the addition of immune checkpoint inhibition (ICI) to OVT further induced lymphocyte infiltration. Consequently, a significant reduction in contralateral non-virus-injected tumors was only visible if OVT was combined with ICI. This strongly indicates that for an effective eradication of GBM cells that cannot be directly targeted by an intratumoral OV injection, additional ICI therapy is required.

Advances in the Immunotherapeutic Potential of Isocitrate Dehydrogenase Mutations in Glioma

Isocitrate dehydrogenase (IDH) is an essential metabolic enzyme in the tricarboxylic acid cycle (TAC). The high mutation frequency of the IDH gene plays a complicated role in gliomas. In addition to affecting gliomas directly, mutations in IDH can also alter their immune microenvironment and can change immune-cell function in direct and indirect ways. IDH mutations mediate immune-cell infiltration and function by modulating immune-checkpoint gene expression and chemokine secretion. In addition, IDH mutation-derived D2-hydroxyglutarate can be absorbed by surrounding immune cells, also affecting their functioning. In this review, we summarize current knowledge about the effects of IDH mutations as well as other gene mutations on the immune microenvironment of gliomas. We also describe recent preclinical and clinical data related to IDH-mutant inhibitors for the treatment of gliomas. Finally, we discuss different types of immunotherapy and the immunotherapeutic potential of IDH mutations in gliomas.

A Systematic Review and Meta-analysis of the Impact of Radiation-Related Lymphopenia on Outcomes in High-Grade Gliomas

Supriya MallickIntroduction  Malignant gliomas are the most common primary malignant brain tumors and are typically treated with maximal safe surgical resection followed by chemoradiation. One of the unintended effects of radiation is depletion of circulating lymphocyte pool, which has been correlated with inferior overall survival outcomes. Methods  A comprehensive and systematic searches of the PubMed, Cochrane Central, and Embase databases were done to assess the studies that have reported radiation-related lymphopenia in high-grade gliomas. Hazard ratios (HRs), odds ratios (OR), and mean differences were represented with Forest plots comparing patients with severe lymphopenia and no severe lymphopenia. Review Manager Version 5.3 (The Nordic Cochrane Centre, Copenhagen, Denmark) was used for the analysis. Results  Nineteen studies were included in the final systematic review and 12 studies were included in the meta-analysis. The odds of developing severe lymphopenia were 0.39 (95% CI:0.19, 0.81, I ²  = 94%, p  = 0.01). Patients with severe lymphopenia were at increased risk of death with a pooled HR = 2.19 (95% CI: 1.70, 2.83, I ²  = 0%, p <0.00001) compared to patients with no severe lymphopenia. The mean difference in survival between patients with severe lymphopenia and no severe lymphopenia was -6.72 months (95% CI: -8.95, -4.49, I ²  = 99%, p <0.00001), with a better mean survival in the no severe lymphopenia group. Conclusion  Radiation-induced severe lymphopenia was associated with poor overall survival and increased risk of death. Photon therapy, larger planning target volume, higher brain dose, higher hypothalamus dose, and female gender were associated with increased risk of severe lymphopenia.

Molecular and clinical features of a potential immunotherapy target ELK3 in glioma

Glioma represents the most prevalent malignant primary brain cancer, and its treatment remains a tremendous challenge. Novel and efficient molecular targets are therefore required for improving diagnosis, survival prediction, and treatment outcomes. Additionally, some studies have shown that immunity is highly associated with glioma progression. Our study aimed to investigate the clinicopathological features, prognostic significance, and immunotherapeutic targetability of ELK3, a member of the erythroblast transformation-specific transcription factor family, in glioma using bioinformatics analyses. ELK3 transcript levels in glioma tissues were evaluated using the Gene Expression Omnibus and The Cancer Genome Atlas databases. Clinical and transcriptomic data of The Cancer Genome Atlas glioma patients were analyzed to identify the molecular and clinical characterizations of ELK3. The prognostic significance of ELK3 was assessed using Cox regression and Kaplan-Meier analysis. The biological pathways related to ELK3 expression were identified by gene set enrichment analysis. The relationships between ELK3 and inflammatory responses, immune cell infiltration, and immune checkpoints were explored using canonical correlation analysis and gene set variation analysis. ELK3 was upregulated in gliomas, and its high expression was correlated with advanced clinicopathologic features and unfavorable prognosis. Gene set enrichment analysis revealed that several immune-related pathways were tightly linked to high ELK3 expression. gene set variation analysis and correlograms demonstrated that ELK3 was robustly associated with inflammatory and immune responses. Correlation analyses indicated that ELK3 was positively associated with infiltrating immune cells and synergistic with several immune checkpoints. ELK3 may serve as a novel marker of poor prognosis and a potential immunotherapeutic target in glioma.

Glioma-Associated Microglia Characterization in the Glioblastoma Microenvironment through a 'Seed-and Soil' Approach: A Systematic Review

Background and aim: Ever since the discovery of tumor-associated immune cells, there has been growing interest in the understanding of the mechanisms underlying the crosstalk between these cells and tumor cells. A "seed and soil" approach has been recently introduced to describe the glioblastoma (GBM) landscape: tumor microenvironments act as fertile "soil" and interact with the "seed" (glial and stem cells compartment). In the following article, we provide a systematic review of the current evidence pertaining to the characterization of glioma-associated macrophages and microglia (GAMs) and microglia and macrophage cells in the glioma tumor microenvironment (TME). Methods: An online literature search was launched on PubMed Medline and Scopus using the following research string: "((Glioma associated macrophages OR GAM OR Microglia) AND (glioblastoma tumor microenvironment OR TME))". The last search for articles pertinent to the topic was conducted in February 2022. Results: The search of the literature yielded a total of 349 results. A total of 235 studies were found to be relevant to our research question and were assessed for eligibility. Upon a full-text review, 58 articles were included in the review. The reviewed papers were further divided into three categories based on their focus: (1) Microglia maintenance of immunological homeostasis and protection against autoimmunity; (2) Microglia crosstalk with dedifferentiated and stem-like glioblastoma cells; (3) Microglia migratory behavior and its activation pattern. Conclusions: Aggressive growth, inevitable recurrence, and scarce response to immunotherapies are driving the necessity to focus on the GBM TME from a different perspective to possibly disentangle its role as a fertile 'soil' for tumor progression and identify within it feasible therapeutic targets. Against this background, our systematic review confirmed microglia to play a paramount role in promoting GBM progression and relapse after treatments. The correct and extensive understanding of microglia-glioma crosstalk could help in understanding the physiopathology of this complex disease, possibly opening scenarios for improvement of treatments.

X-Box Binding Protein 1 (XBP1): A Potential Role in Chemotherapy Response, Clinical Pathologic Features, Non-Inflamed Tumour Microenvironment for Breast Cancer

X-box binding protein 1 (XBP1) is mainly expressed in breast cancer (BC) in human cancers. Its tumorigenesis and favourable prognosis are contradictory, and its essential role in chemotherapeutic response and immunosuppression is unknown in BC. The study firstly identified XBP1 who received neoadjuvant chemotherapy (NAC) from GSE25055 and GSE24460. Associations between XBP1 expression and clinicopathological characteristics was investigated using Oncomine, TCGA, UALCAN and bc-GenExMiner. The prognostic value of XBP1 was assessed using the Kaplan–Meier Plotter, bc-GenExMiner, GSE25055, and GSE25056. Furthermore, we systematically correlated XBP1 and immunological characteristics in the BC tumour microenvironment (TME) using TISIDB, TIMER, GSE25055, GSE25056 and TCGA dataset. Finally, an essential role of XBP1 in chemotherapy response was evaluated based on GSE25055, GSE25065, GSE24460, GSE5846, ROC Plotter and CELL databases. Furthermore, XBP1 mRNA expression levels were obviously highest in BC among human cancers and were significantly related to a good prognosis. In addition, XBP1 mRNA and protein levels were higher in the luminal subtype than in normal tissues and basal-like subtype, which might be attributed to membrane transport-related processes. Apart from BC, negative immunological correlations of XBP1 were not observed in other malignancies. XBP1 might shape the non-inflamed TME in BC. Finally, XBP1 expression was higher in chemo-resistive than chemo-sensitive cases, it had a predictive value and could independently predict chemotherapy response in BC patients receiving NAC. Our study suggests that the essential role of XBP1 in clinical pathologic features, non-inflamed TME, chemotherapy response in BC.

Dual-targeting prodrug nanotheranostics for NIR-Ⅱ fluorescence imaging-guided photo-immunotherapy of glioblastoma

Glioblastoma (GBM) therapy is severely impaired by the blood–brain barrier (BBB) and invasive tumor growth in the central nervous system. To improve GBM therapy, we herein presented a dual-targeting nanotheranostic for second near-infrared (NIR-II) fluorescence imaging-guided photo-immunotherapy. Firstly, a NIR-Ⅱ fluorophore MRP bearing donor-acceptor-donor (D-A-D) backbone was synthesized. Then, the prodrug nanotheranostics were prepared by self-assembling MRP with a prodrug of JQ1 (JPC) and T7 ligand-modified PEG_5k-DSPE. T7 can cross the BBB for tumor-targeted delivery of JPC and MRP. JQ1 could be restored from JPC at the tumor site for suppressing interferon gamma-inducible programmed death ligand 1 expression in the tumor cells. MRP could generate NIR-II fluorescence to navigate 808 nm laser, induce a photothermal effect to trigger in-situ antigen release at the tumor site, and ultimately elicit antitumor immunogenicity. Photo-immunotherapy with JPC and MRP dual-loaded nanoparticles remarkably inhibited GBM tumor growth in vivo. The dual-targeting nanotheranostic might represent a novel nanoplatform for precise photo-immunotherapy of GBM.

The Basis and Advances in Clinical Application of Cytomegalovirus-Specific Cytotoxic T Cell Immunotherapy for Glioblastoma Multiforme

A high percentage of malignant gliomas are infected by human cytomegalovirus (HCMV), and the endogenous expression of HCMV genes and their products are found in these tumors. HCMV antigen expression and its implications in gliomagenesis have emerged as a promising target for adoptive cellular immunotherapy (ACT) strategies in glioblastoma multiforme (GB) patients. Since antigen-specific T cells in the tumor microenvironments lack efficient anti-tumor immune response due to the immunosuppressive nature of glioblastoma, CMV-specific ACT relies on in vitro expansion of CMV-specific CD8+ T cells employing immunodominant HCMV antigens. Given the fact that several hurdles remain to be conquered, recent clinical trials have outlined the feasibility of CMV-specific ACT prior to tumor recurrence with minimal adverse effects and a substantial improvement in median overall survival and progression-free survival. This review discusses the role of HCMV in gliomagenesis, disease prognosis, and recent breakthroughs in harnessing HCMV-induced immunogenicity in the GB tumor microenvironment to develop effective CMV-specific ACT.

Interstitial Control-Released Polymer Carrying a Targeting Small-Molecule Drug Reduces PD-L1 and MGMT Expression in Recurrent High-Grade Gliomas with TMZ Resistance

Simple Summary

This study reports a potential new drug—Cerebraca wafer—that is designed to deliver its active pharmaceutical ingredient, (Z)-n-butylidenephthalide (BP), directly into the surgical cavity created when a brain tumor is resected. The therapeutic mechanism of Cerebraca wafer was shown to involve the following: (1) an IC₅₀ of BP against tumor stem cells four times lower than that of bis-chloroethylnitrosourea (BCNU); (2) a synergistic effect between BP and temozolomide (TMZ), as demonstrated by a reduction in O⁶-methylguanine-DNA-methyltransferase (MGMT) expression level; (3) BP inhibition of programmed cell death-ligand 1 (PD-L1) protein levels, thereby activating T-cell cytotoxicity and increasing interferon-gamma (IFN-γ) secretion. The implantation of Cerebraca wafer is safe, no drug-related adverse events (AEs) and serious AEs (SAEs) were found. The median overall survival (OS) of patients receiving high-dose Cerebraca wafer have exceeded 17.4 months, and a 100% progression-free survival (PFS) rate at six month was achieved. In sum, these findings demonstrate that the Cerebraca wafer has superior therapeutic effects to Gliadel wafer in recurrent high-grade gliomas.

Abstract

In recurrent glioblastoma, Gliadel wafer implantation after surgery has been shown to result in incomplete chemical removal of residual tumor and development of brain edema. Furthermore, temozolomide (TMZ) resistance caused by O⁶-methylguanine-DNA-methyltransferase (MGMT) activation and programmed cell death-ligand 1 (PD-L1) expression leads to immune-cold lesions that result in poorer prognosis. Cerebraca wafer, a biodegradable polymer containing (Z)-n-butylidenephthalide (BP), is designed to eliminate residual tumor after glioma resection. An open-label, one-arm study with four dose cohorts, involving a traditional 3 + 3 dose escalation clinical trial, of the Cerebraca wafer combined with TMZ on patients with recurrent high-grade glioma, was conducted. Of the 12 patients who receive implantation of Cerebraca wafer, there were no drug-related adverse events (AEs) or serious AEs (SAEs). The median overall survival (OS) of patients receiving low-dose Cerebraca wafer was 12 months in the group with >25% wafer coverage of the resected tumor, which is longer than OS duration in previously published studies (Gliadel wafer, 6.4 months). Patients who received high-dose Cerebraca wafer treatment had not yet died at the data cut-off date; a 100% progression-free survival (PFS) rate at six month was achieved, indicating the median OS of cohort IV was more than 17.4 months. In vitro study of the primary cells collected from the patients revealed that the IC₅₀ of BP against tumor stem cells was four times lower than that of bis-chloroethylnitrosourea (BCNU). A synergistic effect between BP and TMZ was demonstrated by a reduction in MGMT expression. Furthermore, BP inhibited PD-L1 expression, thereby activating T-cell cytotoxicity and increasing interferon-gamma (IFN-γ) secretion. The better therapeutic effect of Cerebraca wafer on recurrent high-grade glioma could occur through re-sensitization of TMZ and reduction of PD-L1.

High expression of TXNDC11 indicated unfavorable prognosis of glioma

Background

Thioredoxin domain containing 11 (TXNDC11) has been implicated in numerous cancers. Nevertheless, the function of TXNDC11 in glioma is not well described. This study aimed to assess clinical significance of TXNDC11 in glioma based on bioinformatics analysis and immunohistochemical (IHC) staining.

Methods

GEPIA2, The Cancer Genome Atlas (TCGA), and Gene Expression Omnibus (GEO) databases were employed to detect the levels of TXNDC11 transcript in glioma. Gene expression profiles and data from the methylation chip with clinical details from TCGA and Chinese Glioma Genome Atlas (CGGA) of glioma samples were examined. The methylation of TXNDC11 in glioma was evaluated by 450K methylation chip data analysis. The pathways involved in TXNDC11 expression were screened by gene set enrichment analysis (GSEA). The correlation between TXNDC11 and immune cells was analyzed. Protein level of TXNDC11 was detected by IHC staining in glioma specimens.

Results

TXNDC11 was highly expressed in glioma, and high TXNDC11 expression was associated with poor overall survival (OS) and worse clinical prognostic variables. The methylation of cg04399632 was statistically different between glioma samples and normal samples, and was negatively correlated with TXNDC11 expression in glioma patients. Survival analysis demonstrated a poorer prognosis in glioma patients with cg04399632 hypomethylation. TXNDC11-high phenotype was associated with certain immune-related pathways and other signaling pathways in glioma. The expression of TXNDC11 was correlated positively with M2 macrophage infiltration and negatively with M0 and M1 macrophage infiltration. IHC staining confirmed that TXNDC11 expression increased in higher-grade glioma.

Conclusions

High expression of TXNDC11 may predict unfavorable prognosis of glioma patients.

Expression, prognostic significance and therapeutic implications of PD-L1 in gliomas

The advent of checkpoint immunotherapy, particularly with programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) inhibitors, has provided ground-breaking results in several advanced cancers. Substantial efforts are being made to extend these promising therapies to other refractory cancers such as gliomas, especially glioblastoma, which represents the most frequent and malignant glioma and carries an exceptionally grim prognosis. Thus, there is a need for new therapeutic strategies with related biomarkers. Gliomas have a profoundly immunosuppressive tumour micro-environment and evade immunological destruction by several mechanisms, one being the expression of inhibitory immune checkpoint molecules such as PD-L1. PD-L1 is recognised as an important therapeutic target and its expression has been shown to hold prognostic value in different cancers. Several clinical trials have been launched and some already completed, but PD-1/PD-L1 inhibitors have yet to show convincing clinical efficacy in gliomas. Part of the explanation may reside in the vast molecular heterogeneity of gliomas and a complex interplay within the tumour micro-environment. In parallel, critical knowledge about PD-L1 expression is beginning to accumulate including knowledge on expression levels, testing methodology, co-expression with other checkpoint molecules and prognostic and predictive value. This article reviews these aspects and points out areas where biomarker research is needed to develop more successful checkpoint-related therapeutic strategies in gliomas.

Glioma-targeted multifunctional nanoparticles to co-deliver camptothecin and curcumin for enhanced chemo-immunotherapy

Camptothecin (CPT) is a potent broad-spectrum antitumor agent with efficient therapeutic effect for various cancers. However, its application in glioma therapy has been impeded by the tumor immunosuppressive environment and blood-brain barrier (BBB)-associated drug delivery challenges. Herein, neurotransmitter analogs-modified liposomes (NTs-LIP) were prepared by doping lipidized tryptamine (Tryp) to co-deliver CPT and curcumin (CUR) for improved chemo-immunotherapy in glioma. The introduction of Tryp promotes the delivery efficiency of CPT and CUR across the BBB. CPT inhibits cell proliferation after cellular uptake of NTs-LIP, the combination of which with CUR downregulates the elevated expression of the programmed cell death 1 ligand 1 (PD-L1) caused by CPT to prevent the inactivation of T-cells and synergistically enhance chemo-immunotherapy efficacy. Furthermore, both Tryp and CUR interfere with the indoleamine 2,3-dioxygenase (IDO) pathway to reduce regulatory T cell (Treg)-mediated immunosuppression, exhibiting the potential to combine with PD-L1 inhibition for synergistic antitumor immunity. Taken together, this platform contributes towards targeted delivery and alleviation of the immunosuppressive environment in glioma therapy.

Development of a T-cell activation-related module with predictive value for the prognosis and immune checkpoint blockade therapy response in glioblastoma

Background

Despite the rise in the use of immune checkpoint blockade drugs (ICBs) in recent years, there are no ICB drugs that are currently approved or under large-scale clinical trials for glioblastoma (GBM). T-cells, which mainly mediate adaptive immunity, are an important part of the tumor immune microenvironment. The activation of T-cells in tumors plays a key role in evaluating the sensitivity of patients to immunotherapy. Therefore, we applied bioinformatics approaches to construct a T-cell activation related risk score to study the effect of the activation of T-cells on the prognosis and ICB response of patients with GBM.

Materials and Methods

This study collected TCGA, CGGA, and GSE16011 glioma cohorts, as well as the IMvigor210 immunotherapy dataset, with complete mRNA expression profiles and clinical information. GraphPad Prism 8 and R 3.6.3 were used for bioinformatics analysis and plotting.

Results

The activation of T-cells in patients with GBM is characterized by obvious heterogeneity. We established a T-cell activation-related risk score based on five univariate Cox regression prognostic genes (CD276, IL15, SLC11A1, TNFSF4, and TREML2) in GBM. The risk score was an independent risk factor for poor prognosis. The overall survival time of patients in the high-risk group was significantly lower than in the low-risk group. Moreover, the high-risk score was accompanied by a stronger immune response and a more complex tumor immune microenvironment. “Hot tumors” were mainly enriched in the high-risk group, and high-risk group patients highly expressed inhibitory immune checkpoints (PD1, PD-L1, TIM3 etc.). By combining the risk and priming scores we obtained the immunotherapy score, which was shown to be a good evaluation index for sensitivity to GBM immunotherapy.

Conclusions

As an independent risk factor for poor prognosis, the T-cell activation-related risk score, combined with other clinical characteristics, could efficiently evaluate the survival of patients with GBM. The immunotherapy score obtained by combining the risk and priming scores could evaluate the ICB response of patients with GBM, providing treatment opportunities.

Molecular characteristics of single patient-derived glioma stem-like cells from primary and recurrent glioblastoma

Glioblastoma has high recurrence, while the sensitivity of recurrent glioblastoma to chemotherapy is lower than that of primary glioblastoma. Moreover, there is no standardized treatment for recurrent glioblastoma. Unfortunately, the biological mechanism of recurrent glioblastoma is still unclear, and there are few related studies. We compared the phenotypes of clinical glioblastoma specimens, in-vitro cultured glioma stem-like cells (GSCs) and patient-derived xenograft tumor (PDX) models to explore the molecular genetic characteristics of primary and recurrent glioblastoma from the same patient. In vitro, SU5-2, GSCs derived from recurrent glioblastoma specimens, had stronger proliferative activity and self-renewal ability. Meanwhile, SU5-2 was more resistant to temozolomide and invasive than SU5-1, which derived from primary glioblastoma specimens. Further analysis of the expression of costimulatory molecules showed that the expression of B7-H1, B7-H2 and B7-H3 of SU5-2 were upregulated. In vivo, Kaplan-Meier survival curve analysis showed that the median survival of the recurrent PDX group was worse. The results of gene detection in vitro, PDX model and clinical samples were consistent. Our results showed that the GSCs based on glioblastoma specimens and the PDX models could replicate the main molecular genetic characteristics of original tumors, which provided a reliable experimental platform for both tumor translation kinds of research and screening of molecular therapeutic targets.

CN-3 increases TMZ sensitivity and induces ROS-dependent apoptosis and autophagy in TMZ-resistance glioblastoma

Many glioma patients develop resistance to temozolomide (TMZ) treatment, resulting in reduced efficacy and survival rates. TMZ-resistant cell lines SHG44R and U87R, which highly express O₆ -methylguanine DNA methyltransferase (MGMT) and P-gp, were established. CN-3, a new asterosaponin, showed cytotoxic effects on TMZ-resistant cells in a dose- and time-dependent manner via reactive oxygen species (ROS)-mediated apoptosis and autophagy. Transmission electron microscopy and monodansylcadaverine (MDC) staining showed turgidity of the mitochondria and autophagosomes in CN-3-treated SHG44R and U87R cells. The autophagy inhibitor 3-methyladenine was used to confirm the important role of autophagy in CN-3 cytotoxicity in TMZ-resistant cells. The ROS scavenger N-acetyl- l-cysteine (NAC) attenuated the levels of ROS induced by CN-3 and, therefore, rescued the CN-3 cytotoxic effect on the viability of SHG44R and U87R cells by Cell Counting Kit-8 assays and JuLI-Stage videos. MDC staining also confirmed that NAC rescued an autophagosome increase in CN-3-treated SHG44R and U87R cells. Western blotting revealed that CN-3 increased Bax, cleaved-caspase 3, cytochrome C, PARP-1, LC3-Ⅱ, and Beclin1, and decreased P-AKT, Bcl-2, and p62. Further rescue experiments revealed that CN-3 induced apoptosis and autophagy through ROS-mediated cytochrome C, cleaved-caspase 3, Bcl-2, P-AKT, PARP-1, and LC3-Ⅱ. In addition, CN-3 promoted SHG44R and U87R cells sensitive to TMZ by reducing the expression of P-gp, MGMT, and nuclear factor kappa B p65, and it had a synergistic cytotoxic effect with TMZ. Moreover, CN-3 disrupted the natural cycle arrest and inhibited the migration of SHG44R and U87R cells by promoting cyclin E1 and D1, and by decreasing P21, P27, N-cadherin, β-catenin, transforming growth factor beta 1, and Smad2.

Galectin-9/TIM-3 as a Key Regulator of Immune Response in Gliomas With Chromosome 1p/19q Codeletion

Gliomas with chromosome 1p/19q codeletion were considered a specific tumor entity. This study was designed to reveal the biological function alterations tightly associated with 1p/19q codeletion in gliomas. Clinicopathological and RNA sequencing data from glioma patients were obtained from The Cancer Genome Atlas and Chinese Glioma Genome Atlas databases. Gene set variation analysis was performed to explore the differences in biological functions between glioma subgroups stratified by 1p/19q codeletion status. The abundance of immune cells in each sample was detected using the CIBERSORT analytical tool. Single-cell sequencing data from public databases were analyzed using the t-distributed stochastic neighbor embedding (t-SNE) algorithm, and the findings were verified by in vitro and in vivo experiments and patient samples.We found that the activation of immune and inflammatory responses was tightly associated with 1p/19q codeletion in gliomas. As the most important transcriptional regulator of Galectin-9 in gliomas, the expression level of CCAAT enhancer-binding protein alpha in samples with 1p/19q codeletion was significantly decreased, which led to the downregulation of the immune checkpoints Galectin-9 and TIM-3. These results were validated in three independent datasets. The t-SNE analysis showed that the loss of chromosome 19q was the main reason for the promotion of the antitumor immune response. IHC protein staining, in vitro and in vivo experiments verified the results of bioinformatics analysis. In gliomas, 1p/19q codeletion can promote the antitumor immune response by downregulating the expression levels of the immune checkpoint TIM-3 and its ligand Galectin-9.

Microglial PD-1 stimulation by astrocytic PD-L1 suppresses neuroinflammation and Alzheimer's disease pathology

Chronic neuroinflammation is a pathogenic component of Alzheimer’s disease (AD) that may limit the ability of the brain to clear amyloid deposits and cellular debris. Tight control of the immune system is therefore key to sustain the ability of the brain to repair itself during homeostasis and disease. The immune‐cell checkpoint receptor/ligand pair PD‐1/PD‐L1, known for their inhibitory immune function, is expressed also in the brain. Here, we report upregulated expression of PD‐L1 and PD‐1 in astrocytes and microglia, respectively, surrounding amyloid plaques in AD patients and in the APP/PS1 AD mouse model. We observed juxtamembrane shedding of PD‐L1 from astrocytes, which may mediate ectodomain signaling to PD‐1‐expressing microglia. Deletion of microglial PD‐1 evoked an inflammatory response and compromised amyloid‐β peptide (Aβ) uptake. APP/PS1 mice deficient for PD‐1 exhibited increased deposition of Aβ, reduced microglial Aβ uptake, and decreased expression of the Aβ receptor CD36 on microglia. Therefore, ineffective immune regulation by the PD‐1/PD‐L1 axis contributes to Aβ plaque deposition during chronic neuroinflammation in AD.

HOTAIR Up-Regulation Activates NF-κB to Induce Immunoescape in Gliomas

Background

Checkpoint blockade therapies targeting programmed death ligand 1 (PD-L1) and its receptor programmed cell death 1 promote T cell-mediated immune surveillance against tumors and have been associated with significant clinical benefit in cancer patients. The long-stranded non-coding RNA HOTAIR is highly expressed and associated with metastasis in a variety of cancer types and promotes tumor metastasis at least in part through association with the PRC2 complex that induces redirection to hundreds of genes involved in tumor metastasis. Here, we report that HOTAIR is an activator lncRNA of the NF-κB pathway and demonstrate that its apparent upregulation promotes inflammatory signaling and immune escape in glioma cells.

Methods

Bioinformatics analysis was used to elucidate the relationship between HOTAIR and NF-κB pathway in HOTAIR knockdown glioma cells. At the cytological level, protein hybridization and immunofluorescence were used to detect the response of proteins in the NF-κB signaling pathway to HOTAIR regulation. ChIP and ChIRP experiments identified HOTAIR target genes. Animal experiments verified alterations in inflammation and immune escape following HOTAIR knockdown and activity inhibition.

Results

HOTAIR activated the expression of proteins involved in NF-κB, TNFα, MAPK and other inflammatory signaling pathways. In addition, HOTAIR induced various proteins containing protein kinase structural domains and promoted the enrichment of proteins and complexes of important inflammatory signaling pathways, such as the TNFα/NF-κB signaling protein complex, the IκB kinase complex, and the IKKA-IKKB complex. In addition, HOTAIR aberrantly activated biological processes involved in glioma immune responses, T-cell co-stimulation and transcription initiation by RNA polymerase II. HOTAIR facilitated the induction of IκBα phosphorylation by suppressing the expression of the NF-κB upstream protein UBXN1, promoting NF-κB phosphorylation and nuclear translocation. In vivo, reduction of HOTAIR decreased PD-L1 protein expression, indicating that cells are more likely to be targeted by immune T cells.

Conclusion

In conclusion, our results provide convincing evidence that lncRNA HOTAIR drives aberrant gene transcription and immune escape from tumor cells through the NF-κB pathway.

Clinical characterization and immunosuppressive regulation of CD161 (KLRB1) in glioma through 916 samples

Background

Glioblastoma is a paradigm of cancer‐associated immunosuppression, limiting the effects of immunotherapeutic strategies. Thus, identifying the molecular mechanisms underlying immune surveillance evasion is critical. Recently, the preferential expression of inhibitory natural killer (NK) cell receptor CD161 on glioma‐infiltrating cytotoxic T cells was identified. Focusing on the molecularly annotated, large‐scale clinical samples from different ethnic origins, the data presented here provide evidence of this immune modulator's essential roles in brain tumor biology.

Methods

Retrospective RNA‐seq data analysis was conducted in a cohort of 313 patients with glioma in the Chinese Glioma Genome Atlas (CGGA) database and 603 patients in The Cancer Genome Atlas (TCGA) database. In addition, single‐cell sequencing data from seven surgical specimens of glioblastoma patients and a model in which patient‐derived glioma stem cells were cocultured with peripheral lymphocytes, were used to analyze the molecular evolution process during gliomagenesis.

Results

CD161 was enriched in high‐grade gliomas and isocitrate dehydrogenase (IDH)‐wildtype glioma. CD161 acted as a potential biomarker for the mesenchymal subtype of glioma and an independent prognostic factor for the overall survival (OS) of patients with glioma. In addition, CD161 played an essential role in inhibiting the cytotoxicity of T cells in glioma patients. During the process of gliomagenesis, the expression of CD161 on different lymphocytes dynamically evolved.

Conclusion

The expression of CD161 was closely related to the pathology and molecular pathology of glioma. Meanwhile, CD161 promoted the progression and evolution of gliomas through its unique effect on T cell dysfunction. Thus, CD161 is a promising novel target for immunotherapeutic strategies in glioma treatment.

The immune checkpoint VISTA exhibits high expression levels in human gliomas and associates with a poor prognosis

In human gliomas, anti-tumor T cell responses are inhibited through induction of local and systemic immunosuppression. Immune checkpoint blockade is proving to be a success in several types of cancers. However, many studies reported that the treatment of glioblastoma patients with anti-CTLA-4 or anti-PD-1 has no survival benefit compared to standard chemotherapy. This study aimed to investigate the expression and role of VISTA, a newly described immune checkpoint regulator, in human gliomas. mRNA expression was assessed in a total of 87 samples from glioma patients. 57 glioma tissues were taken at different grades. 20 peripheral blood mononuclear cells (PBMC) samples were taken before surgery and ten after surgery, all from the same set of patients. As for the control, ten specimens of PBMC were taken from healthy donors. Protein expression using immunohistochemistry was performed for 30 patients. The Cancer Genome Atlas (TCGA) data set, was also used to investigate VISTA expression through analysis of RNA-seq data of 667 glioma patients. In the Moroccan cohort, VISTA gene expression was significantly upregulated in glioma tissues related to PBMC of healthy donors. This high expression was specific to patient tissues since VISTA expression in PBMC was low when assessed either before or after surgery. Besides, VISTA exhibited higher expression levels in grade III/IV relative to grade I/II glioma patients. Interestingly, VISTA correlated positively with PD-1 expression. PD-1 also showed elevated expressions in higher glioma grades. The TCGA cohort corroborated these observations. Indeed, VISTA was also found to be strongly expressed in high grades. It was positively correlated with other critical immune checkpoints. Finally, increased VISTA transcript levels were associated with weak overall survival of glioma patients. Our study highlighted a correlation between high levels of VISTA expression and poor prognosis in glioma patients. VISTA might be involved in glioma progression and could be considered as a possible new therapeutic target, especially in advanced gliomas.

Isocitrate Dehydrogenase Mutant Grade II and III Glial Neoplasms

Mutations in isocitrate dehydrogenase (IDH) 1 or IDH2 occur in most of the adult low-grade gliomas and, less commonly, in cholangiocarcinoma, chondrosarcoma, acute myeloid leukemia, and other human malignancies. Cancer-associated mutations alter the function of the enzyme, resulting in production of R(-)-2-hydroxyglutarate and broad epigenetic dysregulation. Small molecule IDH inhibitors have received regulatory approval for the treatment of IDH mutant (mIDH) leukemia and are under development for the treatment of mIDH solid tumors. This article provides a current view of mIDH adult astrocytic and oligodendroglial tumors, including their clinical presentation and treatment, and discusses novel approaches and challenges toward improving the treatment of these tumors.

Toll-like receptors and toll-like receptor-targeted immunotherapy against glioma

Glioma represents a fast proliferating and highly invasive brain tumor which is resistant to current therapies and invariably recurs. Despite some advancements in anti-glioma therapies, patients’ prognosis remains poor. Toll-like receptors (TLRs) act as the first line of defense in the immune system being the detectors of those associated with bacteria, viruses, and danger signals. In the glioma microenvironment, TLRs are expressed on both immune and tumor cells, playing dual roles eliciting antitumoral (innate and adaptive immunity) and protumoral (cell proliferation, migration, invasion, and glioma stem cell maintenance) responses. Up to date, several TLR-targeting therapies have been developed aiming at glioma bulk and stem cells, infiltrating immune cells, the immune checkpoint axis, among others. While some TLR agonists exhibited survival benefit in clinical trials, it attracts more attention when they are involved in combinatorial treatment with radiation, chemotherapy, immune vaccination, and immune checkpoint inhibition in glioma treatment. TLR agonists can be used as immune modulators to enhance the efficacy of other treatment, to avoid dose accumulation, and what brings more interests is that they can potentiate immune checkpoint delayed resistance to PD-1/PD-L1 blockade by upregulating PD-1/PD-L1 overexpression, thus unleash powerful antitumor responses when combined with immune checkpoint inhibitors. Herein, we focus on recent developments and clinical trials exploring TLR-based treatment to provide a picture of the relationship between TLR and glioma and their implications for immunotherapy.