Tumour treating fields therapy for glioblastoma: current advances and future directions

Oncolytic virotherapy improves immunotherapies targeting cancer stemness in glioblastoma

Despite advances in cancer therapies, glioblastoma (GBM) remains the most resistant and recurrent tumor in the central nervous system. GBM tumor microenvironment (TME) is a highly dynamic landscape consistent with alteration in tumor infiltration cells, playing a critical role in tumor progression and invasion. In addition, glioma stem cells (GSCs) with self-renewal capability promote tumor recurrence and induce therapy resistance, which all have complicated eradication of GBM with existing therapies. Oncolytic virotherapy is a promising field of therapy that can kill tumor cells in a targeted manner. Manipulated oncolytic viruses (OVs) improve cancer immunotherapy by directly lysis tumor cells, infiltrating antitumor cells, inducing immunogenic cell death, and sensitizing immune-resistant TME to an immune-responsive hot state. Importantly, OVs can target stemness-driven GBM progression. In this review, we will discuss how OVs as a therapeutic option target GBM, especially the GSC subpopulation, and induce immunogenicity to remodel the TME, which subsequently enhances immunotherapies' efficiency.

Effects of tumor treating fields (TTFields) on human mesenchymal stromal cells

PURPOSE

Mesenchymal stromal cells (MSCs) within the glioblastoma microenvironment have been shown to promote tumor progression. Tumor Treating Fields (TTFields) are alternating electric fields with low intensity and intermediate frequency that exhibit anti-tumorigenic effects. While the effects of TTFields on glioblastoma cells have been studied previously, nothing is known about the influence of TTFields on MSCs.

METHODS

Single-cell RNA sequencing and immunofluorescence staining were employed to identify glioblastoma-associated MSCs in patient samples. Proliferation and clonogenic survival of human bone marrow-derived MSCs were assessed after TTFields in vitro. MSC' characteristic surface marker expression was determined using flow cytometry, while multi-lineage differentiation potential was examined with immunohistochemistry. Apoptosis was quantified based on caspase-3 and annexin-V/7-AAD levels in flow cytometry, and senescence was assessed with ß-galactosidase staining. MSCs' migratory potential was evaluated with Boyden chamber assays.

RESULTS

Single-cell RNA sequencing and immunofluorescence showed the presence of glioblastoma-associated MSCs in patient samples. TTFields significantly reduced proliferation and clonogenic survival of human bone marrow-derived MSCs by up to 60% and 90%, respectively. While the characteristic surface marker expression and differentiation capacity were intact after TTFields, treatment resulted in increased apoptosis and senescence. Furthermore, TTFields significantly reduced MSCs' migratory capacity.

CONCLUSION

We could demonstrate the presence of tumor-associated MSCs in glioblastoma patients, providing a rationale to study the impact of TTFields on MSCs. TTFields considerably increase apoptosis and senescence in MSCs, resulting in impaired survival and migration. The results provide a basis for further analyses on the role of MSCs in glioblastoma patients receiving TTFields.

Anti-tumor effect of innovative tumor treatment device OM-100 through enhancing anti-PD-1 immunotherapy in glioblastoma growth

Glioblastoma (GBM) is associated with a median survival rate of less than 15 months, necessitating innovative treatment approaches. This study investigates the safety and efficacy of the low-frequency magnetic field (LFMF) OM-100 instrument in GBM therapy. In vitro experiments utilized normal astrocyte and GBM cell lines, determining that OM-100 at 100 kHz for 72 h selectively targeted GBM cells without harming normal cells. Subsequent analyses revealed OM-100's impact on cell viability, apoptosis, migration, invasion, reactive oxide species levels, and PD-L1 expression. In vivo studies on mice with U87-induced GBM demonstrated OM-100's synergy with anti-PD-1 therapy, leading to significant tumor volume reduction and increased apoptosis. Notably, OM-100 exhibited safety in healthy mice. Overall, OM-100 could enhance anti-PD-1 immunotherapy effectiveness probably by directly inhibiting tumor proliferation and migration as well as promoting PD-L1 expression, offering a promising therapeutic strategy for GBM treatment.

Breaking Down Glioma-Microenvironment Crosstalk

High-grade gliomas (HGGs) are the commonest primary brain cancers. They are characterized by a pattern of aggressive growth and diffuse infiltration of the host brain that severely limits the efficacy of conventional treatments and patient outcomes, which remain generally poor. Recent work has described a suite of mechanisms via which HGGs interact, predominantly bidirectionally, with various cell types in the host brain including neurons, glial cells, immune cells, and vascular elements to drive tumor growth and invasion. These insights have the potential to inspire novel approaches to HGG therapy that are critically needed. This review explores HGG-host brain interactions and considers whether and how they might be exploited for therapeutic gain.

Targeted Radionuclide Therapy in Glioblastoma

Despite the development of various novel therapies, glioblastoma (GBM) remains a devastating disease, with a median survival of less than 15 months. Recently, targeted radionuclide therapy has shown significant progress in treating solid tumors, with the approval of Lutathera for neuroendocrine tumors and Pluvicto for prostate cancer by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This achievement has shed light on the potential of targeted radionuclide therapy for other solid tumors, including GBM. This review presents the current status of targeted radionuclide therapy in GBM, highlighting the commonly used therapeutic radionuclides emitting alpha, beta particles, and Auger electrons that could induce potent molecular and cellular damage to treat GBM. We then explore a range of targeting vectors, including small molecules, peptides, and antibodies, which selectively target antigen-expressing tumor cells with minimal or no binding to healthy tissues. Considering that radiopharmaceuticals for GBM are often administered locoregionally to bypass the blood-brain barrier (BBB), we review prominent delivery methods such as convection-enhanced delivery, local implantation, and stereotactic injections. Finally, we address the challenges of this therapeutic approach for GBM and propose potential solutions.

Discovery of a Therapeutic Agent for Glioblastoma Using a Systems Biology-Based Drug Repositioning Approach

Glioblastoma (GBM), a highly malignant tumour of the central nervous system, presents with a dire prognosis and low survival rates. The heterogeneous and recurrent nature of GBM renders current treatments relatively ineffective. In our study, we utilized an integrative systems biology approach to uncover the molecular mechanisms driving GBM progression and identify viable therapeutic drug targets for developing more effective GBM treatment strategies. Our integrative analysis revealed an elevated expression of CHST2 in GBM tumours, designating it as an unfavourable prognostic gene in GBM, as supported by data from two independent GBM cohorts. Further, we pinpointed WZ-4002 as a potential drug candidate to modulate CHST2 through computational drug repositioning. WZ-4002 directly targeted EGFR (ERBB1) and ERBB2, affecting their dimerization and influencing the activity of adjacent genes, including CHST2. We validated our findings by treating U-138 MG cells with WZ-4002, observing a decrease in CHST2 protein levels and a reduction in cell viability. In summary, our research suggests that the WZ-4002 drug candidate may effectively modulate CHST2 and adjacent genes, offering a promising avenue for developing efficient treatment strategies for GBM patients.

Positive feedback loop of c-myc/XTP6/NDH2/NF-κB to promote malignant progression in glioblastoma

BACKGROUND

Recent studies have highlighted the significant role of the NF-κB signaling pathway in the initiation and progression of cancer. Furthermore, long noncoding RNAs (lncRNAs) have been identified as pivotal regulators in sustaining the NF-κB signaling pathway's functionality. Despite these findings, the underlying molecular mechanisms through which lncRNAs influence the NF-κB pathway remain largely unexplored.

METHODS

Bioinformatic analyses were utilized to investigate the differential expression and prognostic significance of XTP6. The functional roles of XTP6 were further elucidated through both in vitro and in vivo experimental approaches. To estimate the interaction between XTP6 and NDH2, RNA pulldown and RNA Immunoprecipitation (RIP) assays were conducted. The connection between XTP6 and the IκBα promoter was examined using Chromatin Isolation by RNA Purification (ChIRP) assays. Additionally, Chromatin Immunoprecipitation (ChIP) assays were implemented to analyze the binding affinity of c-myc to the XTP6 promoter, providing insights into the regulatory mechanisms at play.

RESULTS

XTP6 was remarkedly upregulated in glioblastoma multiforme (GBM) tissues and was connected with adverse prognosis in GBM patients. Our investigations revealed that XTP6 can facilitate the malignant progression of GBM both in vitro and in vivo. Additionally, XTP6 downregulated IκBα expression by recruiting NDH2 to the IκBα promoter, which resulted in elevated levels of H3K27me3, thereby reducing the transcriptional activity of IκBα. Moreover, the progression of GBM was further driven by the c-myc-mediated upregulation of XTP6, establishing a positive feedback loop with IκBα that perpetuated the activation of the NF-κB signaling pathway. Notably, the application of an inhibitor targeting the NF-κB signaling pathway effectively inhibited the continuous activation induced by XTP6, leading to a significant reduction in tumor formation in vivo.

CONCLUSION

The results reveal that XTP6 unveils an innovative epigenetic mechanism instrumental in the sustained activation of the NF-κB signaling pathway, suggesting a promising therapeutic target for the treatment of GBM.

Nanoparticles Coated with Brain Microvascular Endothelial Cell Membranes can Target and Cross the Blood-Brain Barrier to Deliver Drugs to Brain Tumors

The blood-brain barrier (BBB) contains tightly connected brain microvascular endothelial cells (BMECs) that hinder drug delivery to the brain, which makes brain tumors difficult to treat. Previous studies have shown that nanoparticles coated with tumor cell membranes selectively target their homologous tumors. Therefore, this study investigated whether bEnd.3-line BMEC membrane-coated nanoparticles with poly(lactide-co-glycolide)-poly(ethylene glycol)-based doxorubicin-loaded cores (BM-PDs) can be used to target BMECs and cross the BBB. In vitro, the BM-PDs effectively target BMECs and cross a BBB model. The BM-PDs enter the BMECs via macropinocytosis, clathrin-mediated endocytosis, caveolin-mediated endocytosis, and membrane fusion, which result in excellent cellular uptake. The BM-PDs also show excellent cellular uptake in brain tumor cells. In vivo, the BM-PDs target BMECs, cross the BBB, accumulate in brain tumors, and efficiently kill tumor cells. Therefore, the proposed strategy has great therapeutic potential owing to its ability to cross the BBB to reach brain tumors.

HMGB2 is a biomarker associated with poor prognosis promoting radioresistance in glioma by targeting base excision repair pathway

BACKGROUND

High mobility group box 2 (HMGB2) is considered as a biomarker of poor prognosis in various cancers.This study aims to investigate the effect and mechanism of HMGB2 in gliomas.

METHODS

With the glioma related on-line and our local hospital databases, the expression differences of HMGB2,Kaplan-Meier survival analysis and COX regression analysis were performed.The correlation analysis between the clinicopathological features and imaging parameters with the HMGB2 expression had been done. Then GSEA and PPI networks were carried out to find out the most significant pathway. The pathway inhibitor was applied to verify HMGB2's participation. CCK8,EDU assays,γ-H2AX immunofluorescence staining and colony formation assay were conducted to observe effects on glioma cells.

RESULTS

Available datasets showed that HMGB2 was highly expressed in glioma and patients with high expression of HMGB2 had poorer prognosis and molecular characteristics. Protein level evidence of western blot and immunohistochemistry from our center supported the conclusions above. Analysis on imaging features suggested that HMGB2 expression level had an inverse association with ADCmean but positively with the thickness of enhancing margin. Results from GSEA and PPI network analysis exhibited that HMGB2 was involved in base excision repair (BER) signaling pathway. Experimental evidence demonstrated that the overexpression of HMGB2 promoted the proliferation of glioma cells and enhanced the radio-resistance.

CONCLUSIONS

HMGB2 could promote glioma development and enhance the radioresistance of glioma cells, potentially related to the BER pathway, suggesting it may serve as an underlying biomarker for patients with glioma.

Minimally-invasive implantable device enhances brain cancer suppression

Current brain tumor treatments are limited by the skull and BBB, leading to poor prognosis and short survival for glioma patients. We introduce a novel minimally-invasive brain tumor suppression (MIBTS) device combining personalized intracranial electric field therapy with in-situ chemotherapeutic coating. The core of our MIBTS technique is a wireless-ultrasound-powered, chip-sized, lightweight device with all functional circuits encapsulated in a small but efficient "Swiss-roll" structure, guaranteeing enhanced energy conversion while requiring tiny implantation windows ( ~ 3 × 5 mm), which favors broad consumers acceptance and easy-to-use of the device. Compared with existing technologies, competitive advantages in terms of tumor suppressive efficacy and therapeutic resolution were noticed, with maximum ~80% higher suppression effect than first-line chemotherapy and 50-70% higher than the most advanced tumor treating field technology. In addition, patient-personalized therapy strategies could be tuned from the MIBTS without increasing size or adding circuits on the integrated chip, ensuring the optimal therapeutic effect and avoid tumor resistance. These groundbreaking achievements of MIBTS offer new hope for controlling tumor recurrence and extending patient survival.

Tumor Treating Fields (TTFields) induce homologous recombination deficiency in ovarian cancer cells, thus mitigating drug resistance

Background

Ovarian cancer is the leading cause of mortality among gynecological malignancies. Carboplatin and poly (ADP-ribose) polymerase inhibitors (PARPi) are often implemented in the treatment of ovarian cancer. Homologous recombination deficient (HRD) tumors demonstrate increased sensitivity to these treatments; however, many ovarian cancer patients are homologous recombination proficient (HRP). TTFields are non-invasive electric fields that induce an HRD-like phenotype in various cancer types. The current study aimed to investigate the impact of TTFields applied together with carboplatin or PARPi (olaparib or niraparib) in preclinical ovarian cancer models.

Methods

A2780 (HRP), OVCAR3 (HRD), and A2780cis (platinum-resistant) human ovarian cancer cells were treated in vitro with TTFields (1 V/cm RMS, 200 kHz, 72 h), alone or with various drug concentrations. Treated cells were measured for cell count, colony formation, apoptosis, DNA damage, expression of DNA repair proteins, and cell cycle. In vivo, ID8-fLuc (HRP) ovarian cancer cells were inoculated intraperitoneally to C57BL/6 mice, which were then treated with either sham, TTFields (200 kHz), olaparib (50 mg/kg), or TTFields plus olaparib; over a period of four weeks. Tumor growth was analyzed using bioluminescent imaging at treatment cessation; and survival analysis was performed.

Results

The nature of TTFields-drug interaction was dependent on the drug's underlying mechanism of action and on the genetic background of the cells, with synergistic interactions between TTFields and carboplatin or PARPi seen in HRP and resistant cells. Treated cells demonstrated elevated levels of DNA damage, accompanied by G2/M arrest, and induction of an HRD-like phenotype. In the tumor-bearing mice, TTFields and olaparib co-treatment resulted in reduced tumor volume and a survival benefit relative to olaparib monotherapy and to control.

Conclusion

By inducing an HRD-like phenotype, TTFields sensitize HRP and resistant ovarian cancer cells to treatment with carboplatin or PARPi, potentially mitigating a-priori and de novo drug resistance, a major limitation in ovarian cancer treatment.

Recurrent Glioblastoma-Molecular Underpinnings and Evolving Treatment Paradigms

Glioblastoma is the most common and lethal central nervous system malignancy with a median survival after progression of only 6-9 months. Major biochemical mechanisms implicated in glioblastoma recurrence include aberrant molecular pathways, a recurrence-inducing tumor microenvironment, and epigenetic modifications. Contemporary standard-of-care (surgery, radiation, chemotherapy, and tumor treating fields) helps to control the primary tumor but rarely prevents relapse. Cytoreductive treatment such as surgery has shown benefits in recurrent glioblastoma; however, its use remains controversial. Several innovative treatments are emerging for recurrent glioblastoma, including checkpoint inhibitors, chimeric antigen receptor T cell therapy, oncolytic virotherapy, nanoparticle delivery, laser interstitial thermal therapy, and photodynamic therapy. This review seeks to provide readers with an overview of (1) recent discoveries in the molecular basis of recurrence; (2) the role of surgery in treating recurrence; and (3) novel treatment paradigms emerging for recurrent glioblastoma.

Programmed cell death disrupts inflammatory tumor microenvironment (TME) and promotes glioblastoma evolution

Glioblastoma (GBM) is the most common malignant brain tumor and has a dismal prognosis even under the current first-line treatment, with a 5-year survival rate less than 7%. Therefore, it is important to understand the mechanism of treatment resistance and develop new anti-tumor strategies. Induction of programmed cell death (PCD) has become a promising anti-tumor strategy, but its effectiveness in treating GBM remains controversial. On the one hand, PCD triggers tumor cell death and then release mediators to draw in immune cells, creating a pro-inflammatory tumor microenvironment (TME). One the other hand, mounting evidence suggests that PCD and inflammatory TME will force tumor cells to evolve under survival stress, leading to tumor recurrence. The purpose of this review is to summarize the role of PCD and inflammatory TME in the tumor evolution of GBM and promising methods to overcome tumor evolution.

Comparative analysis of non-invasive and invasive alternating electric fields therapy for malignant gliomas: a simulation study

Alternating electric fields (AEFs) at intermediate frequencies (100-300 kHz) and low intensities (1-3 V/cm) have shown promise as an effective approach for inhibiting cancer cell proliferation. However, a noticeable research gap exists in comparing the biophysical properties of invasive and non-invasive AEFs methods, and AEFs delivery strategies require further improvement. In this study, we constructed a realistic head model to simulate the effects of non-invasive and invasive AEFs on malignant gliomas. Additionally, a novel method was proposed involving the placement of a return electrode under the scalp. We simulated the electric field and temperature distributions in the brain tissue for each method. Our results underscore the advantages of invasive AEFs, showcasing their superior tumor-targeting abilities and reduced energy requirements. The analysis of brain tissue temperature changes reveals that non-invasive AEFs primarily generate heat at the scalp level, whereas invasive methods localize heat production within the tumor itself, thereby preserving surrounding healthy brain tissue. Our proposed invasive AEFs method also shows potential for selective electric field intervention. In conclusion, invasive AEFs demonstrate potential for precise and effective tumor treatment. Its enhanced targeting capabilities and limited impact on healthy tissue make it a promising avenue for further research in the realm of cancer treatment.

Overcoming Barriers in Glioblastoma-Advances in Drug Delivery Strategies

The world of cancer treatment is evolving rapidly and has improved the prospects of many cancer patients. Yet, there are still many cancers where treatment prospects have not (or hardly) improved. Glioblastoma is the most common malignant primary brain tumor, and even though it is sensitive to many chemotherapeutics when tested under laboratory conditions, its clinical prospects are still very poor. The blood-brain barrier (BBB) is considered at least partly responsible for the high failure rate of many promising treatment strategies. We describe the workings of the BBB during healthy conditions and within the glioblastoma environment. How the BBB acts as a barrier for therapeutic options is described as well as various approaches developed and tested for passing or opening the BBB, with the ultimate aim to allow access to brain tumors and improve patient perspectives.

The tumour microenvironment, treatment resistance and recurrence in glioblastoma

The adaptability of glioblastoma (GBM) cells, encouraged by complex interactions with the tumour microenvironment (TME), currently renders GBM an incurable cancer. Despite intensive research, with many clinical trials, GBM patients rely on standard treatments including surgery followed by radiation and chemotherapy, which have been observed to induce a more aggressive phenotype in recurrent tumours. This failure to improve treatments is undoubtedly a result of insufficient models which fail to incorporate components of the human brain TME. Research has increasingly uncovered mechanisms of tumour-TME interactions that correlate to worsened patient prognoses, including tumour-associated astrocyte mitochondrial transfer, neuronal circuit remodelling and immunosuppression. This tumour hijacked TME is highly implicated in driving therapy resistance, with further alterations within the TME and tumour resulting from therapy exposure inducing increased tumour growth and invasion. Recent developments improving organoid models, including aspects of the TME, are paving an exciting future for the research and drug development for GBM, with the hopes of improving patient survival growing closer. This review focuses on GBMs interactions with the TME and their effect on tumour pathology and treatment efficiency, with a look at challenges GBM models face in sufficiently recapitulating this complex and highly adaptive cancer.

Identification and validation of COL6A1 as a novel target for tumor electric field therapy in glioblastoma

BACKGROUND

Glioblastoma multiforme (GBM) is the most aggressive primary brain malignancy. Novel therapeutic modalities like tumor electric field therapy (TEFT) have shown promise, but underlying mechanisms remain unclear. The extracellular matrix (ECM) is implicated in GBM progression, warranting investigation into TEFT-ECM interplay.

METHODS

T98G cells were treated with TEFT (200 kHz, 2.2 V/m) for 72 h. Collagen type VI alpha 1 (COL6A1) was identified as hub gene via comprehensive bioinformatic analysis based on RNA sequencing (RNA-seq) and public glioma datasets. TEFT intervention models were established using T98G and Ln229 cell lines. Pre-TEFT and post-TEFT GBM tissues were collected for further validation. Focal adhesion pathway activity was assessed by western blot. Functional partners of COL6A1 were identified and validated by co-localization and survival analysis.

RESULTS

TEFT altered ECM-related gene expression in T98G cells, including the hub gene COL6A1. COL6A1 was upregulated in GBM and associated with poor prognosis. Muti-database GBM single-cell analysis revealed high-COL6A1 expression predominantly in malignant cell subpopulations. Differential expression and functional enrichment analyses suggested COL6A1 might be involved in ECM organization and focal adhesion. Western blot (WB), immunofluorescence (IF), and co-immunoprecipitation (Co-IP) experiments revealed that TEFT significantly inhibited expression of COL6A1, hindering its interaction with ITGA5, consequently suppressing the FAK/Paxillin/AKT pathway activity. These results suggested that TEFT might exert its antitumor effects by downregulating COL6A1 and thereby inhibiting the activity of the focal adhesion pathway.

CONCLUSION

TEFT could remodel the ECM of GBM cells by downregulating COL6A1 expression and inhibiting focal adhesion pathway. COL6A1 could interact with ITGA5 and activate the focal adhesion pathway, suggesting that it might be a potential therapeutic target mediating the antitumor effects of TEFT.

WITHDRAWN: Dual targeting of mitochondrial Lon peptidase 1 and chymotrypsin-like protease by small molecule BT317, as potential therapeutics in malignant astrocytomas

The authors have withdrawn their manuscript owing to massive revision and data validation. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

Non-Tumor Cells within the Tumor Microenvironment-The "Eminence Grise" of the Glioblastoma Pathogenesis and Potential Targets for Therapy

Glioblastoma (GBM) is the most common malignancy of the central nervous system in adults. GBM has high levels of therapy failure and its prognosis is usually dismal. The phenotypic heterogeneity of the tumor cells, dynamic complexity of non-tumor cell populations within the GBM tumor microenvironment (TME), and their bi-directional cross-talk contribute to the challenges of current therapeutic approaches. Herein, we discuss the etiology of GBM, and describe several major types of non-tumor cells within its TME, their impact on GBM pathogenesis, and molecular mechanisms of such an impact. We also discuss their value as potential therapeutic targets or prognostic biomarkers, with reference to the most recent works on this subject. We conclude that unless all "key player" populations of non-tumor cells within the TME are considered, no breakthrough in developing treatment for GBM can be achieved.

Insights into Targeted and Stimulus-Responsive Nanocarriers for Brain Cancer Treatment

Brain cancers, especially glioblastoma multiforme, are associated with poor prognosis due to the limited efficacy of current therapies. Nanomedicine has emerged as a versatile technology to treat various diseases, including cancers, and has played an indispensable role in combatting the COVID-19 pandemic as evidenced by the role that lipid nanocarrier-based vaccines have played. The tunability of nanocarrier physicochemical properties -including size, shape, surface chemistry, and drug release kinetics- has resulted in the development of a wide range of nanocarriers for brain cancer treatment. These nanocarriers can improve the pharmacokinetics of drugs, increase blood-brain barrier transfer efficiency, and specifically target brain cancer cells. These unique features would potentially allow for more efficient treatment of brain cancer with fewer side effects and better therapeutic outcomes. This review provides an overview of brain cancers, current therapeutic options, and challenges to efficient brain cancer treatment. The latest advances in nanomedicine strategies are investigated with an emphasis on targeted and stimulus-responsive nanocarriers and their potential for clinical translation.

Continuous iontronic chemotherapy reduces brain tumor growth in embryonic avian in vivo models

Local and long-lasting administration of potent chemotherapeutics is a promising therapeutic intervention to increase the efficiency of chemotherapy of hard-to-treat tumors such as the most lethal brain tumors, glioblastomas (GBM). However, despite high toxicity for GBM cells, potent chemotherapeutics such as gemcitabine (Gem) cannot be widely implemented as they do not efficiently cross the blood brain barrier (BBB). As an alternative method for continuous administration of Gem, we here operate freestanding iontronic pumps - "GemIPs" - equipped with a custom-synthesized ion exchange membrane (IEM) to treat a GBM tumor in an avian embryonic in vivo system. We compare GemIP treatment effects with a topical metronomic treatment and observe that a remarkable growth inhibition was only achieved with steady dosing via GemIPs. Daily topical drug administration (at the maximum dosage that was not lethal for the embryonic host organism) did not decrease tumor sizes, while both treatment regimes caused S-phase cell cycle arrest and apoptosis. We hypothesize that the pharmacodynamic effects generate different intratumoral drug concentration profiles for each technique, which causes this difference in outcome. We created a digital model of the experiment, which proposes a fast decay in the local drug concentration for the topical daily treatment, but a long-lasting high local concentration of Gem close to the tumor area with GemIPs. Continuous chemotherapy with iontronic devices opens new possibilities in cancer treatment: the long-lasting and highly local dosing of clinically available, potent chemotherapeutics to greatly enhance treatment efficiency without systemic side-effects. SIGNIFICANCE STATEMENT: Iontronic pumps (GemIPs) provide continuous and localized administration of the chemotherapeutic gemcitabine (Gem) for treating glioblastoma in vivo. By generating high and constant drug concentrations near the vascularized growing tumor, GemIPs offer an efficient and less harmful alternative to systemic administration. Continuous GemIP dosing resulted in remarkable growth inhibition, superior to daily topical Gem application at higher doses. Our digital modelling shows the advantages of iontronic chemotherapy in overcoming limitations of burst release and transient concentration profiles, and providing precise control over dosing profiles and local distribution. This technology holds promise for future implants, could revolutionize treatment strategies, and offers a new platform for studying the influence of timing and dosing dependencies of already-established drugs in the fight against hard-to-treat tumors.

Advanced tumor electric fields therapy: A review of innovative research and development and prospect of application in glioblastoma

BACKGROUND

Glioblastoma multiforme (GBM) is an aggressive malignant tumor with a high mortality rate and is the most prevalent primary intracranial tumor that remains incurable. The current standard treatment, which involves surgery along with concurrent radiotherapy and chemotherapy, only yields a survival time of 14-16 months. However, the introduction of tumor electric fields therapy (TEFT) has provided a glimmer of hope for patients with newly diagnosed and recurrent GBM, as it has been shown to extend the median survival time to 20 months. The combination of TEFT and other advanced therapies is a promising trend in the field of GBM, facilitated by advancements in medical technology.

AIMS

In this review, we provide a concise overview of the mechanism and efficacy of TEFT. In addition, we mainly discussed the innovation of TEFT and our proposed blueprint for TEFT implementation.

CONCLUSION

Tumor electric fields therapy is an effective and highly promising treatment modality for GBM. The full therapeutic potential of TEFT can be exploited by combined with other innovative technologies and treatments.

Electromagnetic Nature of Distant Interaction of the Atmospheric Pressure Helium Plasma Discharge Tube with Glioblastoma Cancer Cells

Atmospheric pressure coaxial gaseous discharge tubes (DTs) with helium have demonstrated potential for in vitro inactivation or sensitization of glioblastoma cancer cells. Here, we study the effect of two configurations of the DT electrode system on its electromagnetic emissivity as well as other physical factors (heating and UV emission) that form in the vicinity of this device. We demonstrate that the configuration of the DT electrodes that concentrates the discharge streamers near the top of the device has a distant (cm scale) deactivation effect on U87-MG glioblastoma cancer cells when irradiated, without measurable UV components in the DT optical emission spectra. This effect persists even through different barriers such as glass, plastic, or quartz Petri dishes but is eliminated when glass or plastic dishes are filled with water. These findings demonstrate the potential for development of noninvasive, physical-based treatment methods of deep-tissue tumors.

Engineered smart materials for RNA based molecular therapy to treat Glioblastoma

Glioblastoma (GBM) is an aggressive malignancy of the central nervous system (CNS) that remains incurable despite the multitude of improvements in cancer therapeutics. The conventional chemo and radiotherapy post-surgery have only been able to improve the prognosis slightly; however, the development of resistance and/or tumor recurrence is almost inevitable. There is a pressing need for adjuvant molecular therapies that can successfully and efficiently block tumor progression. During the last few decades, non-coding RNAs (ncRNAs) have emerged as key players in regulating various hallmarks of cancer including that of GBM. The levels of many ncRNAs are dysregulated in cancer, and ectopic modulation of their levels by delivering antagonists or overexpression constructs could serve as an attractive option for cancer therapy. The therapeutic potential of several types of ncRNAs, including miRNAs, lncRNAs, and circRNAs, has been validated in both in vitro and in vivo models of GBM. However, the delivery of these RNA-based therapeutics is highly challenging, especially to the tumors of the brain as the blood-brain barrier (BBB) poses as a major obstacle, among others. Also, since RNA is extremely fragile in nature, careful considerations must be met while designing a delivery agent. In this review we have shed light on how ncRNA therapy can overcome the limitations of its predecessor conventional therapy with an emphasis on smart nanomaterials that can aide in the safe and targeted delivery of nucleic acids to treat GBM. Additionally, critical gaps that currently exist for successful transition from viral to non-viral vector delivery systems have been identified. Finally, we have provided a perspective on the future directions, potential pathways, and target areas for achieving rapid clinical translation of, RNA-based macromolecular therapy to advance the effective treatment of GBM and other related diseases.

Cathepsin B-Responsive Programmed Brain Targeted Delivery System for Chemo-Immunotherapy Combination Therapy of Glioblastoma

Tumor-associated macrophages (TAMs) are closely related to the progression of glioblastoma multiform (GBM) and its development of therapeutic resistance to conventional chemotherapy. TAM-targeted therapy combined with conventional chemotherapy has emerged as a promising strategy to combat GBM. However, the presence of the blood-brain barrier (BBB) severely limits the therapeutic efficacy. Meanwhile, the lack of ability to distinguish different targeted cells also poses a challenge for precise therapy. Herein, we propose a cathepsin B (CTSB)-responsive programmed brain-targeted delivery system (D&R-HM-MCA) for simultaneous TAM-targeted and GBM-targeted delivery. D&R-HM-MCA could cross the BBB via low density lipoprotein receptor-associated protein 1 (LRP1)-mediated transcytosis. Upon reaching the GBM site, the outer angiopep-2 modification could be detached from D&R-HM-MCA via cleavage of the CTSB-responsive peptide, which could circumvent abluminal LRP1-mediated efflux. The exposed p-aminophenyl-α-d-mannopyranoside (MAN) modification could further recognize glucose transporter-1 (GLUT1) on GBM and macrophage mannose receptor (MMR) on TAMs. D&R-HM-MCA could achieve chemotherapeutic killing of GBM and simultaneously induce TAM polarization from anti-inflammatory M2 phenotype to pro-inflammatory M1 phenotype, thus resensitizing the chemotherapeutic response and improving anti-GBM immune response. This CTSB-responsive brain-targeted delivery system not only can improve brain delivery efficiency, but also can enable the combination of chemo-immunotherapy against GBM. The effectiveness of this strategy may provide thinking for designing more functional brain-targeted delivery systems and more effective therapeutic regimens.

Glioblastoma Therapy: Past, Present and Future

Glioblastoma (GB) stands out as the most prevalent and lethal form of brain cancer. Although great efforts have been made by clinicians and researchers, no significant improvement in survival has been achieved since the Stupp protocol became the standard of care (SOC) in 2005. Despite multimodality treatments, recurrence is almost universal with survival rates under 2 years after diagnosis. Here, we discuss the recent progress in our understanding of GB pathophysiology, in particular, the importance of glioma stem cells (GSCs), the tumor microenvironment conditions, and epigenetic mechanisms involved in GB growth, aggressiveness and recurrence. The discussion on therapeutic strategies first covers the SOC treatment and targeted therapies that have been shown to interfere with different signaling pathways (pRB/CDK4/RB1/P16ink4, TP53/MDM2/P14arf, PI3k/Akt-PTEN, RAS/RAF/MEK, PARP) involved in GB tumorigenesis, pathophysiology, and treatment resistance acquisition. Below, we analyze several immunotherapeutic approaches (i.e., checkpoint inhibitors, vaccines, CAR-modified NK or T cells, oncolytic virotherapy) that have been used in an attempt to enhance the immune response against GB, and thereby avoid recidivism or increase survival of GB patients. Finally, we present treatment attempts made using nanotherapies (nanometric structures having active anti-GB agents such as antibodies, chemotherapeutic/anti-angiogenic drugs or sensitizers, radionuclides, and molecules that target GB cellular receptors or open the blood-brain barrier) and non-ionizing energies (laser interstitial thermal therapy, high/low intensity focused ultrasounds, photodynamic/sonodynamic therapies and electroporation). The aim of this review is to discuss the advances and limitations of the current therapies and to present novel approaches that are under development or following clinical trials.

Development and Optimisation of Tumour Treating Fields (TTFields) Delivery within 3D Primary Glioma Stem Cell-like Models of Spatial Heterogeneity

Glioblastoma is an aggressive, incurable brain cancer with poor five-year survival rates of around 13% despite multimodal treatment with surgery, DNA-damaging chemoradiotherapy and the recent addition of Tumour Treating Fields (TTFields). As such, there is an urgent need to improve our current understanding of cellular responses to TTFields using more clinically and surgically relevant models, which reflect the profound spatial heterogeneity within glioblastoma, and leverage these biological insights to inform the rational design of more effective therapeutic strategies incorporating TTFields. We have recently reported the use of preclinical TTFields using the inovitroTM system within 2D glioma stem-like cell (GSC) models and demonstrated significant cytotoxicity enhancement when co-applied with a range of therapeutically approved and preclinical DNA damage response inhibitors (DDRi) and chemoradiotherapy. Here we report the development and optimisation of preclinical TTFields delivery within more clinically relevant 3D scaffold-based primary GSC models of spatial heterogeneity, and highlight some initial enhancement of TTFields potency with temozolomide and clinically approved PARP inhibitors (PARPi). These studies, therefore, represent an important platform for further preclinical assessment of TTFields-based therapeutic strategies within clinically relevant 3D GSC models, aimed towards accelerating clinical trial implementation and the ultimate goal of improving the persistently dire survival rates for these patients.

"Tumor Treating Fields" delivered via electromagnetic induction have varied effects across glioma cell lines and electric field amplitudes

Previous studies reported that alternating electric fields (EFs) in the intermediate frequency (100-300 kHz) and low intensity (1-3 V/cm) regime - termed "Tumor Treating Fields" (TTFields) - have a specific, anti-proliferative effect on glioblastoma multiforme (GBM) cells. However, the mechanism(s) of action remain(s) incompletely understood, hindering the clinical adoption of treatments based on TTFields. To advance the study of such treatment in vitro, we developed an inductive device to deliver EFs to cell cultures which improves thermal and osmolar regulation compared to prior devices. Using this inductive device, we applied continuous, 200 kHz electromagnetic fields (EMFs) with a radial EF amplitude profile spanning 0-6.5 V/cm to cultures of primary rat astrocytes and several human GBM cell lines - U87, U118, GSC827, and GSC923 - for a duration of 72 hours. Cell density was assessed via segmented pixel densities from GFP expression (U87, U118) or from staining (astrocytes, GSC827, GSC923). Further RNA-Seq analyses were performed on GSC827 and GSC923 cells. Treated cultures of all cell lines exhibited little to no change in proliferation at lower EF amplitudes (0-3 V/cm). At higher amplitudes (> 4 V/cm), different effects were observed. Apparent cell densities increased (U87), decreased (GSC827, GSC923), or showed little change (U118, astrocytes). RNA-Seq analyses on treated and untreated GSC827 and GSC923 cells revealed differentially expressed gene sets of interest, such as those related to cell cycle control. Up- and down-regulation, however, was not consistent across cell lines nor EF amplitudes. Our results indicate no consistent, anti-proliferative effect of 200 kHz EMFs across GBM cell lines and thus contradict previous in vitro findings. Rather, effects varied across different cell lines and EF amplitude regimes, highlighting the need to assess the effect(s) of TTFields and similar treatments on a per cell line basis.

Bioinspired Lipoproteins of Furoxans-Gemcitabine Preferentially Targets Glioblastoma and Overcomes Radiotherapy Resistance

Radiotherapy (RT) resistance is an enormous challenge in glioblastoma multiforme (GBM) treatment, which is largely associated with DNA repair, poor distribution of reactive radicals in tumors, and limited delivery of radiosensitizers to the tumor sites. Inspired by the aberrant upregulation of RAD51 (a critical protein of DNA repair), scavenger receptor B type 1 (SR-B1), and C-C motif chemokine ligand 5 (CCL5) in GBM patients, a reduction-sensitive nitric oxide (NO) donor conjugate of gemcitabine (RAD51 inhibitor) (NG) is synthesized as radio-sensitizer and a CCL5 peptide-modified bioinspired lipoprotein system of NG (C-LNG) is rationally designed, aiming to preferentially target the tumor sites and overcome the RT resistance. C-LNG can preferentially accumulate at the orthotopic GBM tumor sites with considerable intratumor permeation, responsively release the gemcitabine and NO, and then generate abundant peroxynitrite (ONOO- ) upon X-ray radiation, thereby producing a 99.64% inhibition of tumor growth and a 71.44% survival rate at 120 days in GL261-induced orthotopic GBM tumor model. Therefore, the rationally designed bioinspired lipoprotein of NG provides an essential strategy to target GBM and overcome RT resistance.

Breaking Barriers: A Future Perspective on Glioblastoma Therapy with mRNA-Based Immunotherapies and Oncolytic Viruses

The use of mRNA-based immunotherapies that leverage the genomes of oncolytic viruses holds significant promise in addressing glioblastoma (GBM), an exceptionally aggressive neurological tumor. We explore the significance of mRNA-based platforms in the area of immunotherapy, introducing an innovative approach to mitigate the risks associated with the use of live viruses in cancer treatment. The ability to customize oncolytic virus genome sequences enables researchers to precisely target specific cancer cells, either through viral genome segments containing structural proteins or through a combination of regions with oncolytic potential. This strategy may enhance treatment effectiveness while minimizing unintended impacts on non-cancerous cells. A notable case highlighted here pertains to advanced findings regarding the application of the Zika virus (ZIKV) in GBM treatment. ZIKV, a member of the family Flaviviridae, shows oncolytic properties against GBM, opening novel therapeutic avenues. We explore intensive investigations of glioblastoma stem cells, recognized as key drivers in GBM initiation, progression, and resistance to therapy. However, a comprehensive elucidation of ZIKV's underlying mechanisms is imperative to pave the way for ZIKV-based clinical trials targeting GBM patients. This investigation into harnessing the potential of oncolytic-virus genomes for mRNA-based immunotherapies underscores its noteworthy implications, potentially paving the way for a paradigm shift in cancer treatment strategies.

Breaking Barriers in Neuro-Oncology: A Scoping Literature Review on Invasive and Non-Invasive Techniques for Blood-Brain Barrier Disruption

The blood-brain barrier (BBB) poses a significant challenge to drug delivery for brain tumors, with most chemotherapeutics having limited permeability into non-malignant brain tissue and only restricted access to primary and metastatic brain cancers. Consequently, due to the drug's inability to effectively penetrate the BBB, outcomes following brain chemotherapy continue to be suboptimal. Several methods to open the BBB and obtain higher drug concentrations in tumors have been proposed, with the selection of the optimal method depending on the size of the targeted tumor volume, the chosen therapeutic agent, and individual patient characteristics. Herein, we aim to comprehensively describe osmotic disruption with intra-arterial drug administration, intrathecal/intraventricular administration, laser interstitial thermal therapy, convection-enhanced delivery, and ultrasound methods, including high-intensity focused and low-intensity ultrasound as well as tumor-treating fields. We explain the scientific concept behind each method, preclinical/clinical research, advantages and disadvantages, indications, and potential avenues for improvement. Given that each method has its limitations, it is unlikely that the future of BBB disruption will rely on a single method but rather on a synergistic effect of a combined approach. Disruption of the BBB with osmotic infusion or high-intensity focused ultrasound, followed by the intra-arterial delivery of drugs, is a promising approach. Real-time monitoring of drug delivery will be necessary for optimal results.

Body Fluids Modulate Propagation of Tumor Treating Fields

Tumor treating fields (TTFields) are nonionizing alternating electric fields that have anticancer properties. After the initial approval for use in patients with recurrent glioblastoma in 2011 and newly diagnosed glioblastomas in 2015, they are now being tested in those with advanced lung cancer, ovarian carcinoma, and pancreatic cancer. Unlike ionizing radiation therapy, TTFields have nonlinear propagation characteristics; therefore, it is difficult for clinicians to recognize intuitively the location where these fields have the most impact. However, finite element analysis offers a means of delineating TTFields in the human body. Our analyses in the brain, pelvis, and thorax revealed that cerebrospinal fluid, edema, urine, ascites, pleural fluid, and necrotic core within a tumor greatly influence their distribution within these body cavities. Our observations thus provided a unified framework on the role of these compartmentalized fluids in influencing the propagation of TTFields.

Nanotechnology and Cancer Bioelectricity: Bridging the Gap Between Biology and Translational Medicine

Bioelectricity is the electrical activity that occurs within living cells and tissues. This activity is critical for regulating homeostatic cellular function and communication, and disruptions of the same can lead to a variety of conditions, including cancer. Cancer cells are known to exhibit abnormal electrical properties compared to their healthy counterparts, and this has driven researchers to investigate the potential of harnessing bioelectricity as a tool in cancer diagnosis, prognosis, and treatment. In parallel, bioelectricity represents one of the means to gain fundamental insights on how electrical signals and charges play a role in cancer insurgence, growth, and progression. This review provides a comprehensive analysis of the literature in this field, addressing the fundamentals of bioelectricity in single cancer cells, cancer cell cohorts, and cancerous tissues. The emerging role of bioelectricity in cancer proliferation and metastasis is introduced. Based on the acknowledgement that this biological information is still hard to access due to the existing gap between biological findings and translational medicine, the latest advancements in the field of nanotechnologies for cellular electrophysiology are examined, as well as the most recent developments in micro- and nano-devices for cancer diagnostics and therapy targeting bioelectricity.

Directionally non-rotating electric field therapy delivered through implanted electrodes as a glioblastoma treatment platform: A proof-of-principle study

Background

While directionally rotating tumor-treating fields (TTF) therapy has garnered considerable clinical interest in recent years, there has been comparatively less focus on directionally non-rotating electric field therapy (dnEFT).

Methods

We explored dnEFT generated through customized electrodes as a glioblastoma therapy in in vitro and in vivo preclinical models. The effects of dnEFT on tumor apoptosis and microglia/macrophages in the tumor microenvironment were tested using flow-cytometric and qPCR assays.

Results

In vitro, dnEFT generated using a clinical-grade spinal cord stimulator showed antineoplastic activity against independent glioblastoma cell lines. In support of the results obtained using the clinical-grade electrode, dnEFT delivered through a customized, 2-electrode array induced glioblastoma apoptosis. To characterize this effect in vivo, a custom-designed 4-electrode array was fabricated such that tumor cells can be implanted into murine cerebrum through a center channel equidistant from the electrodes. After implantation with this array and luciferase-expressing murine GL261 glioblastoma cells, mice were randomized to dnEFT or placebo. Relative to placebo-treated mice, dnEFT reduced tumor growth (measured by bioluminescence) and prolonged survival (median survival gain of 6.5 days). Analysis of brain sections following dnEFT showed a notable increase in the accumulation of peritumoral macrophage/microglia with increased expression of M1 genes (IFNγ, TNFα, and IL-6) and decreased expression of M2 genes (CD206, Arg, and IL-10) relative to placebo-treated tumors.

Conclusions

Our results suggest therapeutic potential in glioblastoma for dnEFT delivered through implanted electrodes, supporting the development of a proof-of-principle clinical trial using commercially available deep brain stimulator electrodes.

Pembrolizumab alters the tumor immune landscape in a patient with dMMR glioblastoma

Congenital DNA mismatch repair defects (dMMR), such as Lynch Syndrome, predispose patients to a variety of cancers and account for approximately 1% of glioblastoma cases. While few therapeutic options exist for glioblastoma, checkpoint blockade therapy has proven effective in dMMR tumors. Here we present a case study of a male in their 30s diagnosed with dMMR glioblastoma treated with pembrolizumab who experienced a partial response to therapy. Using a multiplex IHC analysis pipeline on archived slide specimens from tumor resections at diagnosis and after therapeutic interventions, we quantified changes in the frequency and spatial distribution of key cell populations in the tumor tissue. Notably, proliferating (KI67+) macrophages and T cells increased in frequency as did other KI67+ cells within the tumor. Therapeutic intervention remodeled the cellular spatial distribution in the tumor leading to a greater frequency of macrophage/tumor cell interactions and T cell/T cell interactions, highlighting impacts of checkpoint blockade on tumor cytoarchitecture and revealing spatial patterns that may indicate advantageous immune interactions in glioma and other solid tumors treated with these agents.

Combining organotypic tissue culture with light-sheet microscopy (OTCxLSFM) to study glioma invasion

Glioblastoma is a very aggressive tumor and represents the most common primary brain malignancy. Key characteristics include its high resistance against conventional treatments, such as radio- and chemotherapy and its diffuse tissue infiltration, preventing complete surgical resection. The analysis of migration and invasion processes in a physiological microenvironment allows for enhanced understanding of these phenomena and can lead to improved therapeutic approaches. Here, we combine two state-of-the-art techniques, adult organotypic brain tissue slice culture (OTC) and light-sheet fluorescence microscopy (LSFM) of cleared tissues in a combined method termed OTCxLSFM. Using this methodology, we can show that glioblastoma tissue infiltration can be effectively blocked through treatment with arsenic trioxide or WP1066, as well as genetic depletion of the tetraspanin, transmembrane receptor CD9, or signal transducer and activator of transcription 3 (STAT3). With our analysis pipeline, we gain single-cell level, three-dimensional information, as well as insights into the morphological appearance of the tumor cells.

The benefit of complete resection of contrast enhancing tumor in glioblastoma patients: A population-based study

Background

New treatment modalities have not been widely adopted for patients with glioblastoma (GBM) after the addition of temozolomide to radiotherapy. We hypothesize that increased extent of resection (EOR) has resulted in improved survival for surgically treated patients with glioblastoma at the population level.

Methods

Retrospective analysis of adult patients operated for glioblastoma in the population of South-Eastern Norway. Patients were stratified into Pre-temozolomide- (2003-2005), temozolomide- (2006-2012), and resection-focused period (2013-2019) and evaluated according to age and EOR.

Results

The study included 1657 adult patients operated on for supratentorial glioblastoma. The incidence of histologically confirmed glioblastoma increased from 3.7 in 2003 to 5.3 per 100 000 in 2019. The median survival was 11.4 months. Complete resection of contrast-enhancing tumor (CRCET) was achieved in 386 patients, and this fraction increased from 13% to 32% across the periods. Significant improvement in median survival was found between the first 2 periods and the last (10.5 and 10.6 vs. 12.3 months; P < .01), with a significant increase in 3- and 5-year survival probability to 12% and 6% (P < .01). Patients with CRCET survived longer than patients with non-CRCET (16.1 vs. 10.8 months; P < .001). The median survival doubled in patients ≥70 years and (12.1 months). Survival was similar between the time periods in patients where CRCET was achieved.

Conclusions

We demonstrate an improved survival of GBM patients at the population level associated with an increased fraction of patients with CRCET. The data support the importance of CRCET to improve glioblastoma patient outcomes.

Fluoxetine enhances the antitumor effect of olfactory ensheathing cell-thymidine kinase/ganciclovir gene therapy in human glioblastoma multiforme cells through upregulation of Connexin43 levels

Glioblastoma multiforme (GBM) is the most invasive form of primary brain astrocytoma, resulting in poor clinical outcomes. Herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy is considered a promising strategy for GBM treatment. Since Connexin43 (Cx43) expression is reduced in GBM cells, increasing Cx43 levels could enhance the effectiveness of gene therapy. The present study aims to examine the impact of fluoxetine on HSV-TK/GCV gene therapy in human GBM cells using human olfactory ensheathing cells (OECs) as vectors. The effect of fluoxetine on Cx43 levels was assessed using the western blot technique. GBM-derived astrocytes and OECs-TK were Cocultured, and the effect of fluoxetine on the Antitumor effect of OEC-TK/GCV gene therapy was evaluated using MTT assay and flow cytometry. Our results showed that fluoxetine increased Cx43 levels in OECs and GBM cells and augmented the killing effect of OECs-TK on GBM cells. Western blot data revealed that fluoxetine enhanced the Bax/Bcl2 ratio and the levels of cleaved caspase-3 in the coculture of OECs-TK and GBM cells. Moreover, flow cytometry data indicated that fluoxetine increased the percentage of apoptotic cells in the coculture system. This study suggests that fluoxetine, by upregulating Cx43 levels, could strengthen the Antitumor effect of OEC-TK/GCV gene therapy on GBM cells.

Efficacy of tumour-treating fields therapy in recurrent glioblastoma: A narrative review of current evidence

Recurrent Glioblastoma presents a formidable challenge in oncology due to its aggressive nature and limited treatment options. Tumour-Treating Fields (TTFields) Therapy, a novel therapeutic modality, has emerged as a promising approach to address this clinical conundrum. This review synthesizes the current evidence surrounding the efficacy of TTFields Therapy in the context of recurrent Glioblastoma. Diverse academic databases were explored to identify relevant studies published within the last decade. Strategic keyword selection facilitated the inclusion of studies focusing on TTFields Therapy's efficacy, treatment outcomes, and patient-specific factors. The review reveals a growing body of evidence suggesting the potential clinical benefits of TTFields Therapy for patients with recurrent Glioblastoma. Studies consistently demonstrate its positive impact on overall survival (OS) and progression-free survival (PFS). The therapy's safety profile remains favorable, with mild to moderate skin reactions being the most commonly reported adverse events. Our analysis highlights the importance of patient selection criteria, with emerging biomarkers such as PTEN mutation status influencing therapy response. Additionally, investigations into combining TTFields Therapy with other treatments, including surgical interventions and novel approaches, offer promising avenues for enhancing therapeutic outcomes. The synthesis of diverse studies underscores the potential of TTFields Therapy as a valuable addition to the armamentarium against recurrent Glioblastoma. The narrative review comprehensively explains the therapy's mechanisms, clinical benefits, adverse events, and future directions. The insights gathered herein serve as a foundation for clinicians and researchers striving to optimize treatment strategies for patients facing the challenging landscape of recurrent Glioblastoma.

Glycocalyx transduces membrane leak in brain tumor cells exposed to sharp magnetic pulsing

Mechanisms by which electric (E) or magnetic (B) fields might be harnessed to affect tumor cell behavior remain poorly defined, presenting a barrier to translation. We hypothesized in early studies that the glycocalyx of lung cancer cells might play a role in mediating plasma membrane leak by low-frequency pulsed magnetic fields (Lf-PMF) generated on a low-energy solenoid platform. In testing glioblastoma and neuroblastoma cells known to overexpress glycoproteins rich in modifications by the anionic glycan sialic acid (Sia), exposure of brain tumor cells on the same platform to a pulse train that included a 5 min 50Hz Lf-PMF (dB/dt ∼ 2 T/s at 10 ms pulse widths) induced a very modest but significant protease leak above that of control nonexposed cells (with modest but significant reductions in long-term tumor cell viability after the 5 min exposure). Using a markedly higher dB/dt system (80 T/s pulses, 70 μs pulse-width at 5.9 cm from a MagVenture coil source) induced markedly greater leak by the same cells, and eliminating Sia by treating cells with AUS sialidase immediately preexposure abrogated the effect entirely in SH-SY5Y neuroblastoma cells, and partially in T98G glioblastoma cells. The system demonstrated significant leak (including inward leak of propidium iodide), with reduced leak at lower dB/dt in a variety of tumor cells. The ability to abrogate Lf-PMF protease leak by pretreatment with sialidase in SH-SY5Y brain tumor cells or with heparin lyase in A549 lung tumor cells indicated the importance of heavy Sia or heparan sulfate glycosaminoglycan glycocalyx modifications as dominant glycan species mediating Lf-PMF membrane leak in respective tumor cells. This "first-physical" Lf-PMF tumor glycocalyx event, with downstream cell stress, may represent a critical and "tunable" transduction mechanism that depends on characteristic anionic glycans overexpressed by distinct malignant tumors.

Investigation of sponge medium for efficient concurrent tumor treating fields and radiotherapy for glioblastomas

Realizing precise therapy for glioblastomas (GBMs), a kind of high-frequency malignant brain tumor, is of great importance in improving the overall survival (OS) of patients. With relentless efforts made in the past few years, a sponge medium has been introduced into concurrent tumor treating fields (TTFields) and radiotherapy to enhance therapy efficacy for GBMs, and some progresses have been witnessed. However, the specific physical and chemical characteristics of the sponge that can be used for GBMs have not been reported as far as we know. Therefore, this study aims to develop a simple yet robust method to select a candidate sponge medium and verify its safety in advanced concurrent TTFields and radiotherapy for GBMs through interdisciplinary investigation among materials science, medical physics, and clinical radiation oncology. Significantly, latex-free polyurethane (PU) sponges with a Hounsfield unit (HU) value lower than -750, which exhibit almost no negative influence on planning computed tomography (CT) imaging and radiotherapy dosimetry, are demonstrated to be available for concurrent TTFields and radiotherapy for GBMs. Moreover, in clinical research, the achieved clear CT images, negligible scalp toxicity, lower residual positioning errors, and high compliant rate of 82% over the selected representative sponge sample corroborate the availability and safety of PU sponges in practical applications for GBM treatment.

Therapeutic cell-based vaccines for glioblastoma multiforme

Glioblastoma multiforme (GBM), a highly aggressive tumor, poses significant challenges in achieving successful treatment outcomes. Conventional therapeutic modalities including surgery, radiation, and chemotherapy have demonstrated limited efficacy, primarily attributed to the complexities associated with drug delivery to the tumor site and tumor heterogeneity. To address this critical need for innovative therapies, the potential of cancer vaccines utilizing tumor cells and dendritic cells has been explored for GBM treatment. This article provides a comprehensive review of therapeutic vaccinations employing cell-based vaccine strategies for the management of GBM. A meticulous evaluation of 45 clinical trials involving more than 1500 participants revealed that cell-based vaccinations have exhibited favorable safety profiles with minimal toxicity. Moreover, these vaccines have demonstrated modest improvements in overall survival and progression-free survival among patients. However, certain limitations still persist. Notably, there is a need for advancements in the development of potent antigens to evoke immune responses, as well as the optimization of dosage regimens. Consequently, while cell-based vaccinations show promise as a potential therapeutic approach for GBM, further research is imperative to overcome the current limitations. The ultimate objective is to surmount these obstacles and establish cell-based vaccinations as a standard therapeutic modality for GBM.

Spinning magnetic field patterns that cause oncolysis by oxidative stress in glioma cells

Raising reactive oxygen species (ROS) levels in cancer cells to cause macromolecular damage and cell death is a promising anticancer treatment strategy. Observations that electromagnetic fields (EMF) elevate intracellular ROS and cause cancer cell death, have led us to develop a new portable wearable EMF device that generates spinning oscillating magnetic fields (sOMF) to selectively kill cancer cells while sparing normal cells in vitro and to shrink GBM tumors in vivo through a novel mechanism. Here, we characterized the precise configurations and timings of sOMF stimulation that produce cytotoxicity due to a critical rise in superoxide in two types of human glioma cells. We also found that the antioxidant Trolox reverses the cytotoxic effect of sOMF on glioma cells indicating that ROS play a causal role in producing the effect. Our findings clarify the link between the physics of magnetic stimulation and its mechanism of anticancer action, facilitating the development of a potential new safe noninvasive device-based treatment for GBM and other gliomas.

Novel therapeutic strategies in glioma targeting glutamatergic neurotransmission

High grade gliomas carry a poor prognosis despite aggressive surgical and adjuvant approaches including chemoradiotherapy. Recent studies have demonstrated a mitogenic association between neuronal electrical activity and glioma growth involving the PI3K-mTOR pathway. As the predominant excitatory neurotransmitter of the brain, glutamate signalling in particular has been shown to promote glioma invasion and growth. The concept of the neurogliomal synapse has been established whereby glutamatergic receptors on glioma cells have been shown to promote tumour propagation. Targeting glutamatergic signalling is therefore a potential treatment option in glioma. Antiepileptic medications decrease excess neuronal electrical activity and some may possess anti-glutamate effects. Although antiepileptic medications continue to be investigated for an anti-glioma effect, good quality randomised trial evidence is lacking. Other pharmacological strategies that downregulate glutamatergic signalling include riluzole, memantine and anaesthetic agents. Neuromodulatory interventions possessing potential anti-glutamate activity include deep brain stimulation and vagus nerve stimulation - this contributes to the anti-seizure efficacy of the latter and the possible neuroprotective effect of the former. A possible role of neuromodulation as a novel anti-glioma modality has previously been proposed and that hypothesis is extended to include these modalities. Similarly, the significant survival benefit in glioblastoma attributable to alternating electrical fields (Tumour Treating Fields) may be a result of disruption to neurogliomal signalling. Further studies exploring excitatory neurotransmission and glutamatergic signalling and their role in glioma origin, growth and propagation are therefore warranted.

DNA damage response inhibitors enhance tumour treating fields (TTFields) potency in glioma stem-like cells

BACKGROUND

High-grade gliomas are primary brain cancers with unacceptably low and persistent survival rates of 10-16 months for WHO grade 4 gliomas over the last 40 years, despite surgical resection and DNA-damaging chemo-radiotherapy. More recently, tumour-treating fields therapy (TTFields) has demonstrated modest survival benefit and been clinically approved in several countries. TTFields is thought to mediate anti-cancer activity by primarily disrupting mitosis. However, recent data suggest that TTFields may also attenuate DNA damage repair and replication fork dynamics, providing a potential platform for therapeutic combinations incorporating standard-of-care treatments and targeted DNA damage response inhibitors (DDRi).

METHODS

We have used patient-derived, typically resistant, glioma stem-like cells (GSCs) in combination with the previously validated preclinical Inovitro™ TTFields system together with a number of therapeutic DDRi.

RESULTS

We show that TTFields robustly activates PARP- and ATR-mediated DNA repair (including PARylation and CHK1 phosphorylation, respectively), whilst combining TTFields with PARP1 or ATR inhibitor treatment leads to significantly reduced clonogenic survival. The potency of each of these strategies is further enhanced by radiation treatment, leading to increased amounts of DNA damage with profound delay in DNA damage resolution.

CONCLUSION

To our knowledge, our findings represent the first report of TTFields applied with clinically approved or in-trial DDRi in GSC models and provides a basis for translational studies toward multimodal DDRi/TTFields-based therapeutic strategies for patients with these currently incurable tumours.

Molecular Determinants of Calcitriol Signaling and Sensitivity in Glioma Stem-like Cells

Glioblastoma is the most common primary brain cancer in adults and represents one of the worst cancer diagnoses for patients. Suffering from a poor prognosis and limited treatment options, tumor recurrences are virtually inevitable. Additionally, treatment resistance is very common for this disease and worsens the prognosis. These and other factors are hypothesized to be largely due to the fact that glioblastoma cells are known to be able to obtain stem-like traits, thereby driving these phenotypes. Recently, we have shown that the in vitro and ex vivo treatment of glioblastoma stem-like cells with the hormonally active form of vitamin D3, calcitriol (1α,25(OH)2-vitamin D3) can block stemness in a subset of cell lines and reduce tumor growth. Here, we expanded our cell panel to over 40 different cultures and can show that, while half of the tested cell lines are sensitive, a quarter can be classified as high responders. Using genetic and proteomic analysis, we further determined that treatment success can be partially explained by specific polymorphism of the vitamin D3 receptor and that high responders display a proteome suggestive of blockade of stemness, as well as migratory potential.

γδ T cells as a potential therapeutic agent for glioblastoma

Although γδ T cells comprise a small population of T cells, they perform important roles in protecting against infection and suppressing tumors. With their distinct tissue-localizing properties, combined with their various target recognition mechanisms, γδ T cells have the potential to become an effective solution for tumors that do not respond to current therapeutic procedures. One such tumor, glioblastoma (GBM), is a malignant brain tumor with the highest World Health Organization grade and therefore the worst prognosis. The immune-suppressive tumor microenvironment (TME) and immune-evasive glioma stem cells are major factors in GBM immunotherapy failure. Currently, encouraged by the strong anti-tumoral function of γδ T cells revealed at the preclinical and clinical levels, several research groups have shown progression of γδ T cell-based GBM treatment. However, several limitations still exist that block effective GBM treatment using γδ T cells. Therefore, understanding the distinct roles of γδ T cells in anti-tumor immune responses and the suppression mechanism of the GBM TME are critical for successful γδ T cell-mediated GBM therapy. In this review, we summarize the effector functions of γδ T cells in tumor immunity and discuss current advances and limitations of γδ T cell-based GBM immunotherapy. Additionally, we suggest future directions to overcome the limitations of γδ T cell-based GBM immunotherapy to achieve successful treatment of GBM.

Enhancing glioblastoma treatment through the integration of tumor-treating fields

Glioblastoma (GBM) represents a significant therapeutic challenge due to its aggressive nature. Tumor Treating Fields (TTFields) present a promising approach to GBM therapy. The primary mechanism of TTFields, an antimitotic effect, alongside numerous indirect effects including increased cell membrane permeability, signifies their potential in combination with other treatment modalities. Current combinations often include chemotherapy, particularly with temozolomide (TMZ), however, emerging data suggests potential synergy with targeted therapies, radiotherapy, and immunotherapy as well. TTFields display minimal side effects, predominantly skin-related, posing no significant barrier to combined therapies. The effectiveness of TTFields in GBM treatment has been demonstrated through several post-registration studies, advocating for continued research to optimize overall survival (OS) and progression-free survival (PFS) in patients, as opposed to focusing solely on quality of life.

Synergistic effect of TTF and 5-FU combination treatment on pancreatic cancer cells

The present study investigated the therapeutic potential of combining tumor-treating fields (TTF), a novel cancer treatment modality that employs low-intensity, alternating electric fields, with 5-fluorouracil (5-FU), a standard chemotherapy drug used for treating pancreatic cancer. The HPAF-II and Mia-Paca II pancreatic cancer cell lines were treated with TTF, 5-FU, or their combination. Combination treatment produced a significantly greater inhibitory effect on cancer cell proliferation than each single modality. Furthermore, combination therapy induced a substantially higher rate of pancreatic cancer cell apoptosis and exhibited a synergistic effect in clonogenic assays. Additionally, combination treatment showed a greater inhibition of cancer cell migration and invasion than either TTF or 5-FU alone. In conclusion, these findings suggest that the synergistic properties of TTF and 5-FU result in greater therapeutic efficacy against pancreatic cancer cells than either modality alone and may improve survival rates in patients with pancreatic cancer.