The future role of personalized medicine in the treatment of glioblastoma multiforme

Precision medicine advancements in glioblastoma: A systematic review

Background

Glioblastoma multiforme, commonly known as GBM or glioblastoma is a grade IV astrocytoma. Brain tumors are difficult to treat and lead to poor prognosis and survival in patients. Gliomas are categorized into four different grades among which GBM is the worst grade primary brain tumor with a survival of less than a year. The genomic heterogeneity of the brain tumor results in different profiles for patients diagnosed with glioblastoma. Precision medicine focuses on this specific tumor type and suggests specialized treatment for better prognosis and overall survival (OS).

Purpose

With the recent advancements in Genome-Wide Studies (GWS) and various characterizations of brain tumors based on genetic, transcriptomic, proteomic, epigenetic, and metabolomics, this review discusses the advancements and opportunities of precision medicine therapeutics, drugs, and diagnosis methods based on the different profiles of glioblastoma.

Methods

This review has exhaustively surveyed several pieces of works from various literature databases.

Conclusion

It is evident that most primary brain tumors including glioblastoma require specific and precision therapeutics for better prognosis and OS. In present and future, molecular understanding and discovering specific therapies are essential for treatment in the field of neurooncology.

MGMT Gene rs1625649 Polymorphism in Iranian Patients with Brain Glioblastoma: A Case Control Study

Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor with poor prognosis and high potential of dispersion to other brain tissues in adult. Effective and modern choices of treatment including chemotherapy with alkylating agents marginally extend survival of GBM. However, alkylating agents can lead to highly harmful mismatch during DNA replication causing apoptosis and cell death. Accordingly, O6-Methylguanine-DNA methyltransferase (MGMT) removes alkyl adducts, thereby causing resistance to alkylating drugs. Single-Nucleotide Polymorphisms (SNPs) in MGMT promoter region may play a role in the regulation of MGMT expression and prediction of glioma development risk. In order to evaluate the clinical significance of rs1625649 SNP in the MGMT promoter region of glioblastoma, genomic DNA from a series of 54 patients with GBM and 50 healthy individuals in Iranian population were collected for tetra ARMS PCR amplification. None of the "A" or "C" alleles were associated with tumor occurrence, the "AA" genotype was more frequent in healthy subjects, and the "AC" genotype was 4.6 times more common in patients with GBM. The longest survival time was observed in the "CC" genotype; however, this difference was not statistically significant. On the other hand, homozygous rs1625649 (AA genotype) was significantly associated with a better survival than the cases with heterozygous rs1625649 (CA genotype) or wild type rs1625649 (CC genotype), predicting better response to temozolomide-based chemotherapy.

Personalised therapeutic approaches to glioblastoma: A systematic review

Introduction

Glioblastoma is the most common and malignant primary brain tumour with median survival of 14.6 months. Personalised medicine aims to improve survival by targeting individualised patient characteristics. However, a major limitation has been application of targeted therapies in a non-personalised manner without biomarker enrichment. This has risked therapies being discounted without fair and rigorous evaluation. The objective was therefore to synthesise the current evidence on survival efficacy of personalised therapies in glioblastoma.

Methods

Studies reporting a survival outcome in human adults with supratentorial glioblastoma were eligible. PRISMA guidelines were followed. MEDLINE, Embase, Scopus, Web of Science and the Cochrane Library were searched to 5th May 2022. Clinicaltrials.gov was searched to 25th May 2022. Reference lists were hand-searched. Duplicate title/abstract screening, data extraction and risk of bias assessments were conducted. A quantitative synthesis is presented.

Results

A total of 102 trials were included: 16 were randomised and 41 studied newly diagnosed patients. Of 5,527 included patients, 59.4% were male and mean age was 53.7 years. More than 20 types of personalised therapy were included: targeted molecular therapies were the most studied (33.3%, 34/102), followed by autologous dendritic cell vaccines (32.4%, 33/102) and autologous tumour vaccines (10.8%, 11/102). There was no consistent evidence for survival efficacy of any personalised therapy.

Conclusion

Personalised glioblastoma therapies remain of unproven survival benefit. Evidence is inconsistent with high risk of bias. Nonetheless, encouraging results in some trials provide reason for optimism. Future focus should address target-enriched trials, combination therapies, longitudinal biomarker monitoring and standardised reporting.

Natural Products Targeting Hsp90 for a Concurrent Strategy in Glioblastoma and Neurodegeneration

Glioblastoma multiforme (GBM) is one of the most common aggressive, resistant, and invasive primary brain tumors that share neurodegenerative actions, resembling many neurodegenerative diseases. Although multiple conventional approaches, including chemoradiation, are more frequent in GBM therapy, these approaches are ineffective in extending the mean survival rate and are associated with various side effects, including neurodegeneration. This review proposes an alternative strategy for managing GBM and neurodegeneration by targeting heat shock protein 90 (Hsp90). Hsp90 is a well-known molecular chaperone that plays essential roles in maintaining and stabilizing protein folding to degradation in protein homeostasis and modulates signaling in cancer and neurodegeneration by regulating many client protein substrates. The therapeutic benefits of Hsp90 inhibition are well-known for several malignancies, and recent evidence highlights that Hsp90 inhibitors potentially inhibit the aggressiveness of GBM, increasing the sensitivity of conventional treatment and providing neuroprotection in various neurodegenerative diseases. Herein, the overview of Hsp90 modulation in GBM and neurodegeneration progress has been discussed with a summary of recent outcomes on Hsp90 inhibition in various GBM models and neurodegeneration. Particular emphasis is also given to natural Hsp90 inhibitors that have been evidenced to show dual protection in both GBM and neurodegeneration.

Engineering antibody and protein therapeutics to cross the blood-brain barrier

Diseases in the central nervous system (CNS) are often difficult to treat. Antibody- and protein-based therapeutics hold huge promises in CNS disease treatment. However, proteins are restricted from entering the CNS by the blood-brain barrier (BBB). To achieve enhanced BBB crossing, antibody-based carriers have been developed by utilizing the endogenous macromolecule transportation pathway, known as receptor-mediated transcytosis. In this report, we first provided an overall review on key CNS diseases and the most promising antibody- or protein-based therapeutics approved or in clinical trials. We then reviewed the platforms that are being explored to increase the macromolecule brain entry to combat CNS diseases. Finally, we have analyzed the lessons learned from past experiences and have provided a perspective on the future engineering of novel delivery vehicles for antibody- and protein-based therapies for CNS diseases.

Zika Virus: A New Therapeutic Candidate for Glioblastoma Treatment

Glioblastoma (GBM) is the most aggressive among the neurological tumors. At present, no chemotherapy or radiotherapy regimen is associated with a positive long-term outcome. In the majority of cases, the tumor recurs within 32-36 weeks of initial treatment. The recent discovery that Zika virus (ZIKV) has an oncolytic action against GBM has brought hope for the development of new therapeutic approaches. ZIKV is an arbovirus of the Flaviviridae family, and its infection during development has been associated with central nervous system (CNS) malformations, including microcephaly, through the targeting of neural stem/progenitor cells (NSCs/NPCs). This finding has led various groups to evaluate ZIKV's effects against glioblastoma stem cells (GSCs), supposedly responsible for GBM onset, progression, and therapy resistance. While preliminary data support ZIKV tropism toward GSCs, a more accurate study of ZIKV mechanisms of action is fundamental in order to launch ZIKV-based clinical trials for GBM patients.

Monitoring Early Changes in Tumor Metabolism in Response to Therapy Using Hyperpolarized 13C MRSI in a Preclinical Model of Glioma

This study shows the use of hyperpolarized ¹³C magnetic resonance spectroscopic imaging (MRSI) to assess therapeutic efficacy in a preclinical tumor model. ¹³C-labeled pyruvate was used to monitor early changes in tumor metabolism based on the Warburg effect. High-grade malignant tumors exhibit increased glycolytic activity and lactate production to promote proliferation. A rodent glioma model was used to explore altered lactate production after therapy as an early imaging biomarker for therapeutic response. Rodents were surgically implanted with C6 glioma cells and separated into 4 groups, namely, no therapy, radiotherapy, chemotherapy and combined therapy. Animals were imaged serially at 6 different time points with magnetic resonance imaging at 3 T using hyperpolarized [1-¹³C]pyruvate MRSI and conventional ¹H imaging. Using hyperpolarized [1-¹³C]pyruvate MRSI, alterations in tumor metabolism were detected as changes in the conversion of lactate to pyruvate (measured as Lac/Pyr ratio) and compared with the conventional method of detecting therapeutic response using the Response Evaluation Criteria in Solid Tumors. Moreover, each therapy group expressed different characteristic changes in tumor metabolism. The group that received no therapy showed a gradual increase of Lac/Pyr ratio within the tumor. The radiotherapy group showed large variations in tumor Lac/Pyr ratio. The chemo- and combined-therapy groups showed a statistically significant reduction in tumor Lac/Pyr ratio; however, only combined therapy was capable of suppressing tumor growth, which resulted in low endpoint mortality rate. Hyperpolarized ¹³C MRSI detected a prompt reduction in Lac/Pyr ratio as early as 2 days post combined chemo- and radiotherapies.

Glioblastoma Multiforme: An Overview of Emerging Therapeutic Targets

Glioblastoma multiforme (GBM) is the most common and aggressive malignant primary brain tumour in humans and has a very poor prognosis. The existing treatments have had limited success in increasing overall survival. Thus, identifying and understanding the key molecule(s) responsible for the malignant phenotype of GBM will yield new potential therapeutic targets. The treatment of brain tumours faces unique challenges, including the presence of the blood brain barrier (BBB), which limits the concentration of drugs that can reach the site of the tumour. Nevertheless, several promising treatments have been shown to cross the BBB and have shown promising pre-clinical results. This review will outline the status of several of these promising targeted therapies.

Discovery and Therapeutic Exploitation of Mechanisms of Resistance to MET Inhibitors in Glioblastoma

PURPOSE

Glioblastoma (GBM) is the most common and most lethal primary malignant brain tumor. The receptor tyrosine kinase MET is frequently upregulated or overactivated in GBM. Although clinically applicable MET inhibitors have been developed, resistance to single modality anti-MET drugs frequently occurs, rendering these agents ineffective. We aimed to determine the mechanisms of MET inhibitor resistance in GBM and use the acquired information to develop novel therapeutic approaches to overcome resistance.Experimental Design: We investigated two clinically applicable MET inhibitors: crizotinib, an ATP-competitive small molecule inhibitor of MET, and onartuzumab, a monovalent monoclonal antibody that binds to the extracellular domain of the MET receptor. We developed new MET inhibitor-resistant cells lines and animal models and used reverse phase protein arrays (RPPA) and functional assays to uncover the compensatory pathways in MET inhibitor-resistant GBM.

RESULTS

We identified critical proteins that were altered in MET inhibitor-resistant GBM including mTOR, FGFR1, EGFR, STAT3, and COX-2. Simultaneous inhibition of MET and one of these upregulated proteins led to increased cell death and inhibition of cell proliferation in resistant cells compared with either agent alone. In addition, in vivo treatment of mice bearing MET-resistant orthotopic xenografts with COX-2 or FGFR pharmacological inhibitors in combination with MET inhibitor restored sensitivity to MET inhibition and significantly inhibited tumor growth.

CONCLUSIONS

These data uncover the molecular basis of adaptive resistance to MET inhibitors and identify new FDA-approved multidrug therapeutic combinations that can overcome resistance.

A Non-randomized Controlled Trial of EMDR on Affective Symptoms in Patients With Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is a highly aggressive brain cancer and its survival after diagnosis is less than 2 years. Therefore, GBM patients are especially prone to co-occurring psychological conditions such as anxiety and depressive disorders. Furthermore, aggressive medical therapies affect patients' lives, undermining their sense of meaning and coherence. The main aim of this study was to determine the effectiveness of Eye Movement Desensitization and Reprocessing (EMDR) therapy on anxiety, depression and sense of coherence in patients with GBM. Thirty-seven GBM-diagnosed women were included in this trial and received standard medical care. Of those, 18 patients were treated during 4 months with 10-12 individual EMDR sessions (60-90 minutes each). Nineteen GBM patients were used as a non-randomized control group as they consented to psychological evaluations but not to a psychotherapeutic intervention. The groups were homogeneous in terms of gender, age, educational level and treatment, but not in anxiety and depressive levels at baseline. All patients were evaluated at baseline, after treatment (4 months) and at follow-up (further 4 months) by the Hospital Anxiety and Depression Scale (HADS-M) and the Sense of Coherence Scale (SOC-29). Caregivers in both groups were interviewed by the Patient Caregiver Questionnaire after 4 months follow-up. Statistical analyses were conducted using ANOVA statistics, correlation and regression analysis. Results showed a statistically significant decrease in the EMDR group in anxiety, depression and anger, when compared to the experimental group. EMDR therapy also had a positive impact upon the sense of coherence level in the experimental group, whereas in the control group this declined. Finally, the caregivers reported beneficial outcomes of the EMDR therapy with less anxiety- and anger-related behaviors in patients in the experimental group compared to the control group. This study is the first to show beneficial effects of EMDR therapy in alleviating affective symptoms and improving coherence in a severe medically ill population with GBM.

UniPR1331, a small molecule targeting Eph/ephrin interaction, prolongs survival in glioblastoma and potentiates the effect of antiangiogenic therapy in mice

Glioblastoma multiforme (GBM) is the most malignant brain tumor, showing high resistance to standard therapeutic approaches that combine surgery, radiotherapy, and chemotherapy. As opposed to healthy tissues, EphA2 has been found highly expressed in specimens of glioblastoma, and increased expression of EphA2 has been shown to correlate with poor survival rates. Accordingly, agents blocking Eph receptor activity could represent a new therapeutic approach. Herein, we demonstrate that UniPR1331, a pan Eph receptor antagonist, possesses significant in vivo anti-angiogenic and anti-vasculogenic properties which lead to a significant anti-tumor activity in xenograft and orthotopic models of GBM. UniPR1331 halved the final volume of tumors when tested in xenografts (p<0.01) and enhanced the disease-free survival of treated animals in the orthotopic models of GBM both by using U87MG cells (40 vs 24 days of control, p<0.05) or TPC8 cells (52 vs 16 days, p<0.01). Further, the association of UniPR1331 with the anti-VEGF antibody Bevacizumab significantly increased the efficacy of both monotherapies in all tested models. Overall, our data promote UniPR1331 as a novel tool for tackling GBM.

Inhibition of Nucleotide Synthesis Targets Brain Tumor Stem Cells in a Subset of Glioblastoma

Inhibition of both the de novo (DNP) and salvage (NSP) pathways of nucleoside synthesis has been demonstrated to impair leukemia cells. We endeavored to determine whether this approach would be efficacious in glioblastoma. To diminish nucleoside biosynthesis, we utilized compound DI-39, which selectively targets NSP, in combination with thymidine (dT), which selectively targets DNP. We employed in vitro and ex vivo models to determine the effects of pretreatment with dT + DI-39 on brain tumor stem cells (BTSC). Here, we demonstrate that this combinatorial therapy elicits a differential response across a spectrum of human patient-derived glioblastoma cultures. As determined by apoptotic markers, most cultures were relatively resistant to treatment, although a subset was highly sensitive. Sensitivity was unrelated to S-phase delay and to DNA damage induced by treatment. Bioinformatics analysis indicated that response across cultures was associated with the transcription factor PAX3 (associated with resistance) and with canonical pathways, including the nucleotide excision repair pathway, PTEN (associated with resistance), PI3K/AKT (associated with sensitivity), and ErbB2-ErbB3. Our in vitro assays demonstrated that, in sensitive cultures, clonal sphere formation was reduced upon removal from pretreatment. In contrast, in a resistant culture, clonal sphere formation was slightly increased upon removal from pretreatment. Moreover, in an intracranial xenograft model, pretreatment of a sensitive culture caused significantly smaller and fewer tumors. In a resistant culture, tumors were equivalent irrespective of pretreatment. These results indicate that, in the subset of sensitive glioblastoma, BTSCs are targeted by inhibition of pyrimidine synthesis. Mol Cancer Ther; 15(6); 1271-8. ©2016 AACR.

Identifying glioblastoma gene networks based on hypergeometric test analysis

Patient specific therapy is emerging as an important possibility for many cancer patients. However, to identify such therapies it is essential to determine the genomic and transcriptional alterations present in one tumor relative to control samples. This presents a challenge since use of a single sample precludes many standard statistical analysis techniques. We reasoned that one means of addressing this issue is by comparing transcriptional changes in one tumor with those observed in a large cohort of patients analyzed by The Cancer Genome Atlas (TCGA). To test this directly, we devised a bioinformatics pipeline to identify differentially expressed genes in tumors resected from patients suffering from the most common malignant adult brain tumor, glioblastoma (GBM). We performed RNA sequencing on tumors from individual GBM patients and filtered the results through the TCGA database in order to identify possible gene networks that are overrepresented in GBM samples relative to controls. Importantly, we demonstrate that hypergeometric-based analysis of gene pairs identifies gene networks that validate experimentally. These studies identify a putative workflow for uncovering differentially expressed patient specific genes and gene networks for GBM and other cancers.

Feasibility assessment of in vitro chemoresponse assay on stereotactic biopsies of glioblastoma multiforms: a step towards personalized medicine

OBJECTIVES

P In vitro chemosensitivity and resistance assays (CSRAs) are a promising tool for personalized treatment of glioblastoma multiform (GBM). These assays require a minimum of 1 to 2 g of tumor specimen for testing, but this amount is not always accessible. We aimed to assess the feasibility and validity of utilizing stereotactic biopsies of GBM in CSRAs.

MATERIALS AND METHODS

Single cell suspension was prepared from 1 g weight explants of the established xenograft tumor of GBM. Also, primary culture was carried out on 35 mg weight specimens, as a surrogate for stereotactic biopsies. Then, chemoresponse profile of cells obtained by direct cell disaggregation and primary culture was determined using temozolomide and carmustine by clonogenic assay.

RESULTS

There was no statistically significant difference in the cytotoxicity of temozolomide and carmustine between cells obtained from both methods.

CONCLUSION

This work supports the feasibility of using stereotactic biopsies of GBM in CSRAs.

Endothelial cells promote stem-like phenotype of glioma cells through activating the Hedgehog pathway

Microenvironmental regulation of cancer stem cells (CSCs) strongly influences the onset and spread of cancer. The way in which glioma cells interact with their microenvironment and acquire the phenotypes of CSCs remains elusive. We investigated how communication between vascular endothelial cells and glioma cells promoted the properties of glioma stem cells (GSCs). We observed that CD133⁺ GSCs were located closely to Shh⁺ endothelial cells in specimens of human glioblastoma multiforme (GBM). In both in vitro and in vivo studies, we found that endothelial cells promoted the appearance of CSC-like glioma cells, as demonstrated by increases in tumourigenicity and expression of stemness genes such as Sox2, Olig2, Bmi1 and CD133 in glioma cells that were co-cultured with endothelial cells. Knockdown of Smo in glioma cells led to a significant reduction of their CSC-like phenotype formation in vitro and in vivo. Endothelial cells with Shh knockdown failed to promote Hedgehog (HH) pathway activation and CSC-like phenotype formation in co-cultured glioma cells. By examination of glioma tissue specimens from 65 patients, we found that the survival of glioma patients was closely correlated with the expression of both Shh by endothelial cells and Gli1 by perivascular glioma cells. Taken together, our study demonstrates that endothelial cells in the tumour microenvironment provide Shh to activate the HH signalling pathway in glioma cells, thereby promoting GSC properties and glioma propagation. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Glioma and glioblastoma - how much do we (not) know?

Cancer is a heterogeneous disease, which provides a broad field for investigation, while simultaneously reducing the chances for a universal treatment. Malignant gliomas are the most common type of primary brain tumors. The heterogeneity of gliomas regarding clinical presentation, pathology and response to treatment makes this type of tumor a challenging area of research. As the clinical symptoms may be unspecific (e.g., seizures and headaches) it is often difficult to diagnose a patient in the early stages of the disease. Thus far, there are no known genetic patterns of inheritance of this disease. Currently, the treatment of glioblastoma involves surgery, whenever possible, followed by radiation and chemotherapy. Experimental procedures, such as passive and active immunotherapy, use of angiogenesis inhibitors in combination with chemotherapeutics and gene/antibody therapy, are additional treatment options. However, as the brain is difficult to access due to the presence of the blood-brain barrier (BBB), none of the above-mentioned therapies have been successful in curing this disease. The lack of knowledge regarding the mechanisms underlying the development and progression of gliomas further adds to the difficulties. Currently, investigations are focused on the development of novel methods for improving the outcome of this disease. However, despite the extensive investigations, 88% of all glioblastoma multiforme (GBM) patients succumb to the disease within 3 years. GBM remains one of the most challenging malignancies worldwide.