Nanomedicine-based combination therapies for overcoming temozolomide resistance in glioblastomas

Glioblastoma(GBM)is the most common malignant brain tumor.Although current treatment strategies,including surgery,chemotherapy,and radiotherapy,have achieved clinical effects and prolonged the survival of patients,the gradual development of resistance against current therapies has led to a high recurrence rate and treatment failure.Mechanisms underlying the development of resistance involve multiple factors,including drug efflux,DNA damage repair,glioma stem cells,and a hypoxic tumor environment,which are usually correlative and promote each other.As many potential therapeutic targets have been discovered,combination therapy that regulates multiple resistance-related molecule pathways is considered an attractive strategy.In recent years,nanomedicine has revolutionized cancer therapies with optimized accumulation,penetration,internalization,and controlled release.Blood-brain barrier(BBB)penetration efficiency is also significantly improved through modifying ligands on nanomedicine and interacting with the receptors or transporters on the BBB.Moreover,different drugs for combination therapy usually process different pharmacokinetics and biodistribution,which can be further optimized with drug delivery systems to maximize the therapeutic efficiency of combination therapies.Herein the current achievements in nanomedicine-based combination therapy for GBM are discussed.This review aimed to provide a broader understanding of resistance mechanisms and nanomedicine-based combination therapies for future research on GBM treatment.

HSP90B1-mediated plasma membrane localization of GLUT1 promotes radioresistance of glioblastomas

Ionizing radiation is a popular and effective treatment option for glioblastoma(GBM).However,resistance to radiation therapy inevitably occurs during treatment.It is urgent to investigate the mechanisms of radioresistance in GBM and to find ways to improve radiosensitivity.Here,we found that heat shock protein 90 beta family member 1(HSP90B1)was significantly upregulated in radioresistant GBM cell lines.More importantly,HSP90B1 promoted the localization of glucose transporter type 1,a key rate-limiting factor of glycolysis,on the plasma membrane,which in turn enhanced glycolytic activity and subsequently tumor growth and radioresistance of GBM cells.These findings imply that targeting HSP90B1 may effectively improve the efficacy of radiotherapy for GBM patients,a potential new approach to the treatment of glioblastoma.

Prognostic significance of annexin VII expression in glioblastomas multiforme in humans

OBJECT:Glioblastoma multiforme(GBM)is the most common and lethal primary brain tumor in adults.It isnearly uniformly fatal,with a median survival time of approximately l year,despite modem treatment modalities.Nevertheless,a range of survival times exists around this median.Efforts to understand why some patients livelonger or shorter than the average may provide insight into the biology of these neoplasms.The annexin VII(ANX7)gene is located on the human chromosome 10q21,a site long hypothesized to harbor tumor

Resolving the lineage relationship between malignant cells and vascular cells in glioblastomas

Glioblastoma multiforme(GBM),a highly malignant and heterogeneous brain tumor,contains various types of tumor and non-tumor cells.Whether GBM cells can trans-differentiate into non-neural cell types,including mural cells or endothelial cells(ECs),to support tumor growth and invasion remains controversial.Here we generated two genetic GBM models de novo in immunocompetent mouse brains,mimicking essential pathological and molecular features of human GBMs.Lineage-tracing and transplantation studies demonstrated that,although blood vessels in GBM brains underwent drastic remodeling,evidence of trans-differentiation of GBM cells into vascular cells was barely detected.Intriguingly,GBM cells could promiscuously express markers for mural cells during gliomagenesis.Furthermore,single-cell RNA sequencing showed that patterns of copy number variations(CNVs)of mural cells and ECs were distinct from those of GBM cells,indicating discrete origins of GBM cells and vascular components.Importantly,single-cell CNV analysis of human GBM specimens also suggested that GBM cells and vascular cells are likely separate lineages.Rather than expansion owing to trans-differentiation,vascular cell expanded by proliferation during tumorigenesis.Therefore,cross-lineage trans-differentiation of GBM cells is very unlikely to occur during gliomagenesis.Our findings advance understanding of cell lineage dynamics during gliomagenesis,and have implications for targeted treatment of GBMs.

NUDT5 promotes the growth,metastasis,and Warburg effect of IDH wild-type glioblastoma multiforme cells by upregulating TRIM47

Objective:To explore the regulatory mechanism of NUDT5 in glioblastoma multiforme(GBM).Methods:GEPIA database was used to predict the expressions of NUDT5 and tripartite motif family proteins 47(TRIM47)in GBM patients.RT-qPCR and Western blot analyses were performed to examine NUDT5 expression in GBM cells.LN-229 cell proliferation,migration as well as invasion were estimated by CCK-8,colony formation,wound healing,and Transwell assays following interference with NUDT5.ECAR assay,L-lactic acid kit,glucose detection kit,and ATP detection kit were applied for the detection of glycolysis-related indexes.Co-immunoprecipitation experiment was carried out to verify the relationship between NUDT5 and TRIM47.Results:GEPIA database showed that NUDT5 expression was significantly increased in GBM patients.Inhibiting the expression of NUDT5 in GBM cells significantly suppressed the viability,proliferation,invasion,migration,and glycolysis of GBM cells.Moreover,TRIM47 was highly expressed in GBM cells and interacted with NUDT5.Overexpression of TRIM47 partially reversed the inhibitory effect of NUDT5 downregulation on the proliferation,metastasis,and glycolysis of GBM cells.Conclusions:NUDT5 promotes the growth,metastasis,and Warburg effect of GBM cells by upregulating TRIM47.Both NUDT5 and TRIM47 can be used as targets for GMB treatment.

GRIK1 promotes glioblastoma malignancy and is a novel prognostic factor of poor prognosis

Primary tumors of the central nervous system(CNS)are classified into over 100 different histological types.The most common type of glioma is derived from astrocytes,and the most invasive glioblastoma(WHO IV)accounts for over 57%of these tumors.Glioblastoma(GBM)is the most common and fatal tumor of the CNS,with strong growth and invasion capabilities,which makes complete surgical resection almost impossible.Despite various treatment methods such as surgery,radiotherapy,and chemotherapy,glioma is still an incurable disease,and the median survival time of patients with GBM is shorter than 15 months.Thus,molecular mechanisms of GBM characteristic invasive growth need to be clarified to improve the poor prognosis.Glutamate ionotropic receptor kainate type subunit 1(GRIK1)is essential for brain function and is involved in many mental and neurological diseases.However,GRIK1’s pathogenic roles and mechanisms in GBM are still unknown.Single-nuclear RNA sequencing of primary and recurrent GBM samples revealed that GRIK1 expression was noticeably higher in the recurrent samples.Moreover,immunohistochemical staining of an array of GBM samples showed that high levels of GRIK1 correlated with poor prognosis of GBM,consistent with The Cancer Genome Atlas database.Knockdown of GRIK1 retarded GBM cells growth,migration,and invasion.Taken together,these findings show that GRIK1 is a unique and important component in the development of GBM and may be considered as a biomarker for the diagnosis and therapy in individuals with GBM.

A review on potential heterocycles for the treatment of glioblastoma targeting receptor tyrosine kinases

Glioblastoma,the most aggressive form of brain tumor,poses significant challenges in terms of treatment success and patient survival.Current treatment modalities for glioblastoma include radiation therapy,surgical intervention,and chemotherapy.Unfortunately,the median survival rate remains dishearteningly low at 12–15 months.One of the major obstacles in treating glioblastoma is the recurrence of tumors,making chemotherapy the primary approach for secondary glioma patients.However,the efficacy of drugs is hampered by the presence of the blood-brain barrier and multidrug resistance mechanisms.Consequently,considerable research efforts have been directed toward understanding the underlying signaling pathways involved in glioma and developing targeted drugs.To tackle glioma,numerous studies have examined kinase-downstream signaling pathways such as RAS-RAF-MEKERK-MPAK.By targeting specific signaling pathways,heterocyclic compounds have demonstrated efficacy in glioma therapeutics.Additionally,key kinases including phosphatidylinositol 3-kinase(PI3K),serine/threonine kinase,cytoplasmic tyrosine kinase(CTK),receptor tyrosine kinase(RTK)and lipid kinase(LK)have been considered for investigation.These pathways play crucial roles in drug effectiveness in glioma treatment.Heterocyclic compounds,encompassing pyrimidine,thiazole,quinazoline,imidazole,indole,acridone,triazine,and other derivatives,have shown promising results in targeting these pathways.As part of this review,we propose exploring novel structures with low toxicity and high potency for glioma treatment.The development of these compounds should strive to overcome multidrug resistance mechanisms and efficiently penetrate the blood-brain barrier.By optimizing the chemical properties and designing compounds with enhanced drug-like characteristics,we can maximize their therapeutic value and minimize adverse effects.Considering the complex nature of glioblastoma,these novel structures should be rigorously tested and evaluated for their efficacy and safety profiles.

Targeting brain tumors with innovative nanocarriers:bridging the gap through the blood-brain barrier

Background:Glioblastoma multiforme(GBM)is recognized as the most lethal and most highly invasive tumor.The high likelihood of treatment failure arises fromthe presence of the blood-brain barrier(BBB)and stemcells around GBM,which avert the entry of chemotherapeutic drugs into the tumormass.Objective:Recently,several researchers have designed novel nanocarrier systems like liposomes,dendrimers,metallic nanoparticles,nanodiamonds,and nanorobot approaches,allowing drugs to infiltrate the BBB more efficiently,opening up innovative avenues to prevail over therapy problems and radiation therapy.Methods:Relevant literature for this manuscript has been collected from a comprehensive and systematic search of databases,for example,PubMed,Science Direct,Google Scholar,and others,using specific keyword combinations,including“glioblastoma,”“brain tumor,”“nanocarriers,”and several others.Conclusion:This review also provides deep insights into recent advancements in nanocarrier-based formulations and technologies for GBM management.Elucidation of various scientific advances in conjunction with encouraging findings concerning the future perspectives and challenges of nanocarriers for effective brain tumor management has also been discussed.

Impacts of Nutlin-3a and exercise on murine double minute 2-enriched glioma treatment

Recent research has demonstrated the impact of physical activity on the prognosis of glioma patients,with evidence suggesting exercise may reduce mortality risks and aid neural regeneration.The role of the small ubiquitin-like modifier(SUMO)protein,especially post-exercise,in cancer progression,is gaining attention,as are the potential anti-cancer effects of SUMOylation.We used machine learning to create the exercise and SUMO-related gene signature(ESLRS).This signature shows how physical activity might help improve the outlook for low-grade glioma and other cancers.We demonstrated the prognostic and immunotherapeutic significance of ESLRS markers,specifically highlighting how murine double minute 2(MDM2),a component of the ESLRS,can be targeted by nutlin-3.This underscores the intricate relationship between natural compounds such as nutlin-3 and immune regulation.Using comprehensive CRISPR screening,we validated the effects of specific ESLRS genes on low-grade glioma progression.We also revealed insights into the effectiveness of Nutlin-3a as a potent MDM2 inhibitor through molecular docking and dynamic simulation.Nutlin-3a inhibited glioma cell proliferation and activated the p53 pathway.Its efficacy decreased with MDM2 overexpression,and this was reversed by Nutlin-3a or exercise.Experiments using a low-grade glioma mouse model highlighted the effect of physical activity on oxidative stress and molecular pathway regulation.Notably,both physical exercise and Nutlin-3a administration improved physical function in mice bearing tumors derived from MDM2-overexpressing cells.These results suggest the potential for Nutlin-3a,an MDM2 inhibitor,with physical exercise as a therapeutic approach for glioma management.Our research also supports the use of natural products for therapy and sheds light on the interaction of exercise,natural products,and immune regulation in cancer treatment.

Stem cell technology for antitumor drug loading and delivery in oncology

The main aim of antineoplastic treatment is to maximize patient benefit by augmenting the drug accumulation within affected organs and tissues,thus incrementing drug effects and,at the same time,reducing the damage of non-involved tissues to cytotoxic agents.Mesenchymal stromal cells(MSC)represent a group of undifferentiated multipotent cells presenting wide self-renewal features and the capacity to differentiate into an assortment of mesenchymal family cells.During the last year,they have been proposed as natural carriers for the selective release of antitumor drugs to malignant cll,s thus optimizing cytotoxic action on cancer cll,while significantly reducing adverse side efect on healthy cells.MSC chemotherapeutic drug loading and delivery is an encouraging new area of cell therapy for several tumors,especially for those with unsatisfactory prognosis and limited treatment options available.Although some experim ental models have been sucesfuly developed,phase I dinical studies are needed to confirm this potential application of cell therapy,in particular in the case of primary and secondary lung cancers.

Celastrol inhibits inflammatory factors expression in glioblastoma

Background:Glioblastoma is one of the most common primary intracranial tumors of the central nervous system in adults.Although chemotherapy is an important component of glioblastoma treatment,its effectiveness remains unsatisfactory.Due to multiple immunosuppressive mechanisms,glioblastoma immunotherapy has not been effective in treating many patients as a result of the clinical breakthroughs in the field.Therefore,the development of cancer immunotherapy relies on the understanding of how tumors interact with the immune system and the analysis of their molecular determinants.This study identified the key interactions between immune cells in the glioma microenvironment using RNA microarrays and single-cell sequencing.Methods:First,we screened differentially expressed genes in tumor and control samples from GSE29796 and GSE50161 datasets using GEO2R.All differentially expressed genes were used to perform enrichment analysis and construct protein-protein interaction topological analysis to analyze the interaction between proteins.Using single-cell RNA sequencing data from the GSE162631 database,we identified immune cell types within the glioblastoma microenvironment,and validated the hub gene expression in these cells.In addition,based on the GEPIA and TIMER databases,hub genes were investigated and compared with immune infiltration to determine differential expression.Finally,CellChat was used to visualize the gene expression distribution and cell-to-cell communication analysis of the proteins between different types of cells.Results:We found that monocytes/macrophages may communicate with each other in the tumor microenvironment through MIF-(CD74+CXCR4)and MIF-(CD74+CD44).In addition,our study indicated that celastrol has the ability to inhibit inflammatory factors expression by MIF/CD74 signaling pathway in U87 cells.Conclusion:This study improved the effectiveness of cancer immunotherapy strategies and developed new ideas for immunotherapy that can be applied to glioblastoma.

The interplay mechanism between IDH mutation, MGMT-promoter methylation, and PRMT5 activity in the progression of grade 4 astrocytoma: unraveling the complex triad theory

Background:The dysregulation of Isocitrate dehydrogenase(IDH)and the subsequent production of 2-Hydroxyglutrate(2HG)may alter the expression of epigenetic proteins in Grade 4 astrocytoma.The interplay mechanism between IDH,O-6-methylguanine-DNA methyltransferase(MGMT)-promoter methylation,and protein methyltransferase proteins-5(PRMT5)activity,with tumor progression has never been described.Methods:A retrospective cohort of 34 patients with G4 astrocytoma is classified into IDH-mutant and IDH-wildtype tumors.Both groups were tested for MGMT-promoter methylation and PRMT5 through methylation-specific and gene expression PCR analysis.Inter-cohort statistical significance was evaluated.Results:Both IDH-mutant WHO grade 4 astrocytomas(n=22,64.7%)and IDH-wildtype glioblastomas(n=12,35.3%)had upregulated PRMT5 gene expression except in one case.Out of the 22 IDH-mutant tumors,10(45.5%)tumors showed MGMT-promoter methylation and 12(54.5%)tumors had unmethylated MGMT.All IDH-wildtype tumors had unmethylated MGMT.There was a statistically significant relationship between MGMT-promoter methylation and IDH in G4 astrocytoma(p-value=0.006).Statistically significant differences in progression-free survival(PFS)were also observed among all G4 astrocytomas that expressed PRMT5 and received either temozolomide(TMZ)or TMZ plus other chemotherapies,regardless of their IDH or MGMT-methylation status(p-value=0.0014).Specifically,IDH-mutant tumors that had upregulated PRMT5 activity and MGMT-promoter methylation,who received only TMZ,have exhibited longer PFS.Conclusions:The relationship between PRMT5,MGMT-promoter,and IDH is not tridirectional.However,accumulation of D2-hydroxyglutarate(2-HG),which partially activates 2-OG-dependent deoxygenase,may not affect their activities.In IDH-wildtype glioblastomas,the 2HG-2OG pathway is typically inactive,leading to PRMT5 upregulation.TMZ alone,compared to TMZ-plus,can increase PFS in upregulated PRMT5 tumors.Thus,using a PRMT5 inhibitor in G4 astrocytomas may help in tumor regression.

Focus on current and emerging treatment options for glioma:A comprehensive review

This comprehensive review delves into the current updates and challenges associated with the management of low-grade gliomas(LGG),the predominant primary tumors in the central nervous system.With a general incidence rate of 5.81 per 100000,gliomas pose a significant global concern,necessitating advancements in treatment techniques to reduce mortality and morbidity.This review places a particular focus on immunotherapies,discussing promising agents such as Zotiraciclib and Lerapolturev.Zotiraciclib,a CDK9 inhibitor,has demonstrated efficacy in glioblastoma treatment in preclinical and clinical studies,showing its potential as a therapeutic breakthrough.Lerapolturev,a viral immunotherapy,induces inflammation in glioblastoma and displays positive outcomes in both adult and pediatric patients.Exploration of immunotherapy extends to Pembrolizumab,Nivolumab,and Entrectinib,revealing the challenges and variabilities in patient responses.Despite promising preclinical data,the monoclonal antibody Depatuxizumab has proven ineffective in glioblastoma treatment,emphasizing the critical need to understand resistance mechanisms.The review also covers the success of radiation therapy in pediatric LGG,with evolving techniques,such as proton therapy,showing potential improvements in patient quality of life.Surgical treatment is discussed in the context of achieving a balance between preserving the patient’s quality of life and attaining gross total resection,with the extent of surgical resection significantly influencing the survival outcomes.In addition to advancements in cancer vaccine development,this review highlights the evolving landscape of LGG treatment,emphasizing a shift toward personalized and targeted therapies.Ongoing research is essential for refining strategies and enhancing outcomes in the management of LGG.

Application of Convolutional Neural Networks in Classification of GBM for Enhanced Prognosis

The lethal brain tumor “Glioblastoma” has the propensity to grow over time. To improve patient outcomes, it is essential to classify GBM accurately and promptly in order to provide a focused and individualized treatment plan. Despite this, deep learning methods, particularly Convolutional Neural Networks (CNNs), have demonstrated a high level of accuracy in a myriad of medical image analysis applications as a result of recent technical breakthroughs. The overall aim of the research is to investigate how CNNs can be used to classify GBMs using data from medical imaging, to improve prognosis precision and effectiveness. This research study will demonstrate a suggested methodology that makes use of the CNN architecture and is trained using a database of MRI pictures with this tumor. The constructed model will be assessed based on its overall performance. Extensive experiments and comparisons with conventional machine learning techniques and existing classification methods will also be made. It will be crucial to emphasize the possibility of early and accurate prediction in a clinical workflow because it can have a big impact on treatment planning and patient outcomes. The paramount objective is to not only address the classification challenge but also to outline a clear pathway towards enhancing prognosis precision and treatment effectiveness.

Cerebral Glioblastoma in Renal Transplant Recipient: A Case Report

Cancers is a leading cause of mortality among transplant recipients. The most common cancers are skin tumors. Glioblastoma is the most frequent brain tumor in adults aged 45 - 70 years. It accounts for 12% - 15% of all intracranial tumors. It is characterized by its rapid development and poor prognosis. We report the case of a cerebral glioblastoma in a kidney transplant recipient. Clinical case: Mr G.R, 44 years old caucasian patient who underwent kidney transplantation. Immunosuppressive treatment included cyclosporine, mycophenolate mofetil and methylprednisolone. Creatinine levels after transplantation remained stable at 11 mg/L (96.8 μmol/l) with an estimated glomerular filtration rate (eGFR) of 77 ml/min/1.73m2 after a 15 years of follow-up. A grade IV right fronto-callossal cerebral glioblastoma was diagnosed in our patient. EBV PCR was negative. Therefore, he underwent 25 sessions of radiotherapy combined with oral chemotherapy using temozolomide. One month later, the patient died due to cerebral edema with subfalcine herniation. Conclusion: This is a case of cerebral glioblastoma in a kidney transplant recipient, a population considered at risk for tumor development due to immunosuppressive treatment. This emphasizes the need for a lifelong surveillance and, more importantly a better balance between graft function preservation and the risks associated with immunosuppressants.

Racl＋ cells distributed in accordance with CD 133＋ cells in glioblastomas and the elevated invasiveness of CD 133＋ glioma cells with higher Racl activity

Background Recent studies have suggested that cancer stem cells are one of the major causes for tumor recurrence due to their resistance to radiotherapy and chemotherapy. Although the highly invasive nature of glioblastoma （GBM） cells is also implicated in the failure of current therapies, it is not clear how glioma stem cells （GSCs） are involved in invasiveness. Racl activity is necessary for inducing reorganization of actin cytoskeleton and cell movement. In this study, we aimed to investigate the distribution characteristics of CD133＋ cells and Racl＋ cells in GBM as well as Racl activity in CD133＋ GBM cells, and analyze the migration and invasion potential of these cells. Methods A series of 21 patients with GBM were admitted consecutively and received tumor resection in Tianjin Medical University General Hospital during the first half of the year 2011. Tissue specimens were collected both from the peripheral and the central parts for each tumor under magnetic resonance imaging （MRI） navigation guidance. Immunohistochemical staining was used to detect the CD133＋ cells and Racl＋ cells distribution in GBM specimens. Double-labeling immunofluorescence was further used to analyze CD133 and Racl co-expression and the relationship between CD133＋ cells distribution and Racl expression. Serum-free medium culture and magnetic sorting were used to isolate CD133＋ cells from U87 cell line. Racl activation assay was conducted to assess the activation of Racl in CD133＋ and CD133- U87 cells. The migration and invasive ability of CD133＋ and CD133- U87 cells were determined by cell migration and invasion assays in vitro. Student＇s t-test and one-way analysis of variance （ANOVA） test were used to determine statistical significance in this study. Results In the central parts of GBMs, CD133＋ cells were found to cluster around necrosis and occasionally cluster around the vessels under the microscope by immunohistological staining. In the peripheral parts of the tumors, CD133＋ cells were lined up along the basement membrane of the vessels and myelinated nerve fibers. Racl expression was high and diffused in the central parts of the GBMs, and the Racl＋ cells were distributed basically in accordance with CD133＋ cells both in the central and peripheral parts of GBMs. In double-labeling immunofluorescence, Racl was expressed in （83.14＋4.23）% of CD133＋ cells, and CD133 and Racl co-expressed cells were located around the vessels in GBMs. Significantly higher amounts of Racl-GTP were expressed in the CD133＋ cells （0.378±0.007）, compared to CD133- cells （0.195±0.004） （t=-27.81; P 〈0.05）. CD133＋ cells had stronger ability to migrate （74.34±2.40 vs. 38.72±2.60, t=42.71, P 〈0.005） and invade （52.00±2.28 vs. 31.26±1.82, t=30.76, P 〈0.005）, compared to their counterpart CD133- cells in transwell cell migration/invasion assay. Conclusions These data suggest that CD133＋ GBM cells highly express Racl and have greater potential to migrate and invade through activated Racl-GTP. The accordance of distribution between Racl＋ cells and CD133＋ cells in GBMs implies that Racl might be an inhibited target to prevent invasion and migration and to avoid malignant glioma recurrence

Leveraging Metabolomics to Assess the Next Generation of Temozolomide-based Therapeutic Approaches for Glioblastomas

Glioblastoma multiforme （GBM） is the most common adult primary tumor of the cen- tral nervous system. The current standard of care for glioblastoma patients involves a combination of surgery, radiotherapy and chemotherapy with the alkylating agent temozolomide. Several mech- anisms underlying the inherent and acquired temozolomide resistance have been identified and con- tribute to treatment failure. Early identification of temozolomide-resistant GBM patients and improvement of the therapeutic strategies available to treat this malignancy are of uttermost impor- tance. This review initially looks at the molecular pathways underlying GBM formation and devel- opment with a particular emphasis placed on recent therapeutic advances made in the field. Our focus will next be directed toward the molecular mechanisms modulating temozolomide resistance in GBM patients and the strategies envisioned to circumvent this resistance. Finallyl we highlight the diagnostic and prognostic value of metabolomics in cancers and assess its potential usefulness in improving the current standard of care for GBM patients.

The association between human cytomegalovirus and glioblastomas: a review

Human cytomegalovirus (HCMV) was reported in glioblastoma multiforme (GBM) over a decade ago and this finding has the potential to increase our understanding of the disease and it offers an alternative tumor-specific therapeutic target. Due of this promise, there is a fair amount of time, energy and money being directed towards understanding and utilizing this connection for eventual therapeutic purposes. Nevertheless, the association between GBM and HCMV remains controversial. Several studies have reported conflicting results, further undermining the potential clinical value of this association. In this review, the authors will discuss the latest developments on this evolving issue. Specifically, the results of the latest studies, both positive and negative, will be discussed. Furthermore, potential theories to explain discrepancies reported in the literature will be proposed. Clinical implications including potential targets for anti-HCMV therapy and the latest developments in anti-HCMV therapy will be presented. Finally, solutions to remedy this controversial issue in neuro-oncology will be offered.

Novel approaches to combat chemoresistance against glioblastomas

The poor prognosis of glioblastoma multiforme(GBM)patients is in part due to resistance to current standard-of-care treatments including chemotherapy[predominantly temozolomide(TMZ;Temodar)],radiation therapy and an anti-angiogenic therapy[an antibody against the vascular endothelial growth factor(bevacizumab;Avastin)],resulting in recurrent tumors.Several recurrent GBM tumors are commonly resistant to either TMZ,radiation or bevacizumab,which contributes to the low survival rate for GBM patients.This review will focus on novel targets and therapeutic approaches that are currently being considered to combat GBM chemoresistance.One of these therapeutic options is a small molecule called OKlahoma Nitrone 007(OKN-007),which was discovered to inhibit the transforming growth factor β1 pathway,reduce TMZ-resistance and enhance TMZ-sensitivity.OKN-007 is currently an investigational new drug in clinical trials for both newly-diagnosed and recurrent GBM patients.Another novel target is ELTD1(epidermal growth factor,latrophilin and seven transmembrane domain-containing protein 1;alternatively known as ADGRL4,Adhesion G protein-coupled receptor L4),which we used a monoclonal antibody against,where a therapy against it was found to inhibit Notch 1 in a pre-clinical GBM xenograft model.Notch 1 is known to be associated with chemoresistance in GBM.Other potential therapeutic targets to combat GBM chemoresistance include the phosphoinositide 3-kinase pathway,nuclear factor-κB,the hepatocyte/scatter factor(c-MET),the epidermal growth factor receptor,and the tumor microenvironment.

The role of extracellular vesicles in acquisition of resistance to therapy in glioblastomas

Glioblastoma(GBM)is the most aggressive primary brain tumor with a median survival of 15 months despite standard care therapy consisting of maximal surgical debulking,followed by radiation therapy with concurrent and adjuvant temozolomide treatment.The natural history of GBM is characterized by inevitable recurrence with patients dying from increasingly resistant tumor regrowth after therapy.Several mechanisms including inter-and intratumoral heterogeneity,the evolution of therapy-resistant clonal subpopulations,reacquisition of stemness in glioblastoma stem cells,multiple drug efflux mechanisms,the tumor-promoting microenvironment,metabolic adaptations,and enhanced repair of drug-induced DNA damage have been implicated in therapy failure.Extracellular vesicles(EVs)have emerged as crucial mediators in the maintenance and establishment of GBM.Multiple seminal studies have uncovered the multi-dynamic role of EVs in the acquisition of drug resistance.Mechanisms include EV-mediated cargo transfer and EVs functioning as drug efflux channels and decoys for antibody-based therapies.In this review,we discuss the various mechanisms of therapy resistance in GBM,highlighting the emerging role of EV-orchestrated drug resistance.Understanding the landscape of GBM resistance is critical in devising novel therapeutic approaches to fight this deadly disease.