Tumor-treating fields (TTFields) induce immunogenic cell death resulting in enhanced antitumor efficacy when combined with anti-PD-1 therapy

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.

Global post‑marketing safety surveillance of Tumor Treating Fields (TTFields) therapy in over 25,000 patients with CNS malignancies treated between 2011-2022

BACKGROUND

Tumor Treating Fields (TTFields) are alternating electric fields that disrupt cancer cell processes. TTFields therapy is approved for recurrent glioblastoma (rGBM), and newly-diagnosed (nd) GBM (with concomitant temozolomide for ndGBM; US), and for grade IV glioma (EU). We present an updated global, post-marketing surveillance safety analysis of patients with CNS malignancies treated with TTFields therapy.

METHODS

Safety data were collected from routine post-marketing activities for patients in North America, Europe, Israel, and Japan (October 2011-October 2022). Adverse events (AEs) were stratified by age, sex, and diagnosis.

RESULTS

Overall, 25,898 patients were included (diagnoses: ndGBM [68%], rGBM [26%], anaplastic astrocytoma/oligodendroglioma [4%], other CNS malignancies [2%]). Median (range) age was 59 (3-103) years; 66% patients were male. Most (69%) patients were 18-65 years; 0.4% were < 18 years; 30% were > 65 years. All-cause and TTFields-related AEs occurred in 18,798 (73%) and 14,599 (56%) patients, respectively. Most common treatment-related AEs were beneath-array skin reactions (43%), electric sensation (tingling; 14%), and heat sensation (warmth; 12%). Treatment-related skin reactions were comparable in pediatric (39%), adult (42%), and elderly (45%) groups, and in males (41%) and females (46%); and similar across diagnostic subgroups (ndGBM, 46%; rGBM, 34%; anaplastic astrocytoma/oligodendroglioma, 42%; other, 40%). No TTFields-related systemic AEs were reported.

CONCLUSIONS

This long-term, real-world analysis of > 25,000 patients demonstrated good tolerability of TTFields in patients with CNS malignancies. Most therapy-related AEs were manageable localized, non-serious skin events. The TTFields therapy safety profile remained consistent across subgroups (age, sex, and diagnosis), indicative of its broad applicability.

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.

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.

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.

Tumor-treating fields in cancer therapy: advances of cellular and molecular mechanisms

Tumor-Treating Fields (TTFields) use intermediate-frequency and low-intensity electric fields to inhibit tumor cells. However, their mechanisms are still not well understood. This article reviews their key antitumor mechanisms at the cellular and molecular levels, including inhibition of proliferation, induction of death, disturbance of migration, and activation of the immune system. The multifaceted biological effects in combination with other cancer treatments are also summarized. The deep insight into their mechanism will help develop more potential antitumor treatments.

Understanding the immunosuppressive microenvironment of glioma: mechanistic insights and clinical perspectives

Glioblastoma (GBM), the predominant and primary malignant intracranial tumor, poses a formidable challenge due to its immunosuppressive microenvironment, thereby confounding conventional therapeutic interventions. Despite the established treatment regimen comprising surgical intervention, radiotherapy, temozolomide administration, and the exploration of emerging modalities such as immunotherapy and integration of medicine and engineering technology therapy, the efficacy of these approaches remains constrained, resulting in suboptimal prognostic outcomes. In recent years, intensive scrutiny of the inhibitory and immunosuppressive milieu within GBM has underscored the significance of cellular constituents of the GBM microenvironment and their interactions with malignant cells and neurons. Novel immune and targeted therapy strategies have emerged, offering promising avenues for advancing GBM treatment. One pivotal mechanism orchestrating immunosuppression in GBM involves the aggregation of myeloid-derived suppressor cells (MDSCs), glioma-associated macrophage/microglia (GAM), and regulatory T cells (Tregs). Among these, MDSCs, though constituting a minority (4-8%) of CD45+ cells in GBM, play a central component in fostering immune evasion and propelling tumor progression, angiogenesis, invasion, and metastasis. MDSCs deploy intricate immunosuppressive mechanisms that adapt to the dynamic tumor microenvironment (TME). Understanding the interplay between GBM and MDSCs provides a compelling basis for therapeutic interventions. This review seeks to elucidate the immune regulatory mechanisms inherent in the GBM microenvironment, explore existing therapeutic targets, and consolidate recent insights into MDSC induction and their contribution to GBM immunosuppression. Additionally, the review comprehensively surveys ongoing clinical trials and potential treatment strategies, envisioning a future where targeting MDSCs could reshape the immune landscape of GBM. Through the synergistic integration of immunotherapy with other therapeutic modalities, this approach can establish a multidisciplinary, multi-target paradigm, ultimately improving the prognosis and quality of life in patients with GBM.

Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot

Immunotherapy has emerged as a promising cancer treatment option in recent years. In immune "hot" tumors, characterized by abundant immune cell infiltration, immunotherapy can improve patients' prognosis by activating the function of immune cells. By contrast, immune "cold" tumors are often less sensitive to immunotherapy owing to low immunogenicity of tumor cells, an immune inhibitory tumor microenvironment, and a series of immune-escape mechanisms. Immunogenic cell death (ICD) is a promising cellular process to facilitate the transformation of immune "cold" tumors to immune "hot" tumors by eliciting innate and adaptive immune responses through the release of (or exposure to) damage-related molecular patterns. Accumulating evidence suggests that various traditional therapies can induce ICD, including chemotherapy, targeted therapy, radiotherapy, and photodynamic therapy. In this review, we summarize the biological mechanisms and hallmarks of ICD and introduce some newly discovered and technologically innovative inducers that activate the immune system at the molecular level. Furthermore, we also discuss the clinical applications of combing ICD inducers with cancer immunotherapy. This review will provide valuable insights into the future development of ICD-related combination therapeutics and potential management for "cold" tumors.

Tumor Treating Fields (TTFields) combined with the drug repurposing approach CUSP9v3 induce metabolic reprogramming and synergistic anti-glioblastoma activity in vitro

BACKGROUND

Glioblastoma represents a brain tumor with a notoriously poor prognosis. First-line therapy may include adjunctive Tumor Treating Fields (TTFields) which are electric fields that are continuously delivered to the brain through non-invasive arrays. On a different note, CUSP9v3 represents a drug repurposing strategy that includes 9 repurposed drugs plus metronomic temozolomide. Here, we examined whether TTFields enhance the antineoplastic activity of CUSP9v3 against this disease.

METHODS

We performed preclinical testing of a multimodal approach of TTFields and CUSP9v3 in different glioblastoma models.

RESULTS

TTFields had predominantly synergistic inhibitory effects on the cell viability of glioblastoma cells and non-directed movement was significantly impaired when combined with CUSP9v3. TTFields plus CUSP9v3 significantly enhanced apoptosis, which was associated with a decreased mitochondrial outer membrane potential (MOMP), enhanced cleavage of effector caspase 3 and reduced expression of Bcl-2 and Mcl-1. Moreover, oxidative phosphorylation and expression of respiratory chain complexes I, III and IV was markedly reduced.

CONCLUSION

TTFields strongly enhance the CUSP9v3-mediated anti-glioblastoma activity. TTFields are currently widely used for the treatment of glioblastoma patients and CUSP9v3 was shown to have a favorable safety profile in a phase Ib/IIa trial (NCT02770378) which facilitates transition of this multimodal approach to the clinical setting.

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.

Treatment advances in high-grade gliomas

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

Tumor treating fields suppress tumor cell growth and neurologic decline in models of spinal metastases

Spinal metastases can result in severe neurologic compromise and decreased overall survival. Despite treatment advances, local disease progression is frequent, highlighting the need for novel therapies. Tumor treating fields (TTFields) impair tumor cell replication and are influenced by properties of surrounding tissue. We hypothesized that bone's dielectric properties will enhance TTFields-mediated suppression of tumor growth in spinal metastasis models. Computational modeling of TTFields intensity was performed following surgical resection of a spinal metastasis and demonstrated enhanced TTFields intensity within the resected vertebral body. Additionally, luciferase-tagged human KRIB osteosarcoma and A549 lung adenocarcinoma cell lines were cultured in demineralized bone grafts and exposed to TTFields. Following TTFields exposure, the bioluminescence imaging (BLI) signal decreased to 10%-80% of baseline, while control cultures displayed a 4.48- to 9.36-fold increase in signal. Lastly, TTFields were applied in an orthotopic murine model of spinal metastasis. After 21 days of treatment, control mice demonstrated a 5-fold increase in BLI signal compared with TTFields-treated mice. TTFields similarly prevented tumor invasion into the spinal canal and development of neurologic symptoms. Our data suggest that TTFields can be leveraged as a local therapy within minimally conductive bone of spinal metastases. This provides the groundwork for future studies investigating TTFields for patients with treatment-refractory spinal metastases.

Theory and application of TTFields in newly diagnosed glioblastoma

BACKGROUND

Glioblastoma is the most common primary malignant brain tumor in adults. TTFields is a therapy that use intermediate-frequency and low-intensity alternating electric fields to treat tumors. For patients with ndGBM, the addition of TTFields after the concurrent chemoradiotherapy phase of the Stupp regimen can improve prognosis. However, TTFields still has the potential to further prolong the survival of ndGBM patients.

AIM

By summarizing the mechanism and application status of TTFields in the treatment of ndGBM, the application prospect of TTFields in ndbm treatment is prospected.

METHODS

We review the recent literature and included 76 articles to summarize the mechanism of TTfields in the treatment of ndGBM. The current clinical application status and potential health benefits of TTFields in the treatment of ndGBM are also discussed.

RESULTS

TTFields can interfere with tumor cell mitosis, lead to tumor cell apoptosis and increased autophagy, hinder DNA damage repair, induce ICD, activate tumor immune microenvironment, reduce cancer cell metastasis and invasion, and increase BBB permeability. TTFields combines with chemoradiotherapy has made progress, its optimal application time is being explored and the problems that need to be considered when retaining the electrode patches for radiotherapy are further discussed. TTFields shows potential in combination with immunotherapy, antimitotic agents, and PARP inhibitors, as well as in patients with subtentorial gliomas.

CONCLUSION

This review summarizes mechanisms of TTFields in the treatment of ndGBM, and describes the current clinical application of TTFields in ndGBM. Through the understanding of its principle and application status, we believe that TTFields still has the potential to further prolong the survival of ndGBM patients. Thus,research is still needed to explore new ways to combine TTFields with other therapies and optimize the use of TTFields to realize its full potential in ndGBM patients.

MGMT in TMZ-based glioma therapy: Multifaceted insights and clinical trial perspectives

Temozolomide (TMZ) is the most preferred and approved chemotherapeutic drug for either first- or second-line chemotherapy for glioma patients across the globe. In glioma patients, resistance to treatment with alkylating drugs like TMZ is known to be conferred by exalted levels of MGMT gene expression. On the contrary, epigenetic silencing through MGMT gene promoter methylation leading to subsequent reduction in MGMT transcription and protein expression, is predicted to have a response favoring TMZ treatment. Thus, MGMT protein level in cancer cells is a crucial determining factor in indicating and predicting the choice of alkylating agents in chemotherapy or choosing glioma patients directly for a second line of treatment. Thus, in-depth research is necessary to achieve insights into MGMT gene regulation that has recently enticed a fascinating interest in epigenetic, transcriptional, post-transcriptional, and post-translational levels. Furthermore, MGMT promoter methylation, stability of MGMT protein, and related subsequent adaptive responses are also important contributors to strategic developments in glioma therapy. With applications to its identification as a prognostic biomarker, thus predicting response to advanced glioma therapy, this review aims to concentrate on the mechanistic role and regulation of MGMT gene expression at epigenetic, transcriptional, post-transcriptional, and post-translational levels functioning under the control of multiple signaling dynamics.

Enhanced Photodynamic Therapy Synergizing with Inhibition of Tumor Neutrophil Ferroptosis Boosts Anti-PD-1 Therapy of Gastric Cancer

For tumor treatment, the ultimate goal in tumor therapy is to eliminate the primary tumor, manage potential metastases, and trigger an antitumor immune response, resulting in the complete clearance of all malignant cells. Tumor microenvironment (TME) refers to the local biological environment of solid tumors and has increasingly become an attractive target for cancer therapy. Neutrophils within TME of gastric cancer (GC) spontaneously undergo ferroptosis, and this process releases oxidized lipids that limit T cell activity. Enhanced photodynamic therapy (PDT) mediated by di-iodinated IR780 (Icy7) significantly increases the production of reactive oxygen species (ROS). Meanwhile, neutrophil ferroptosis can be triggered by increased ROS generation in the TME. In this study, a liposome encapsulating both ferroptosis inhibitor Liproxstatin-1 and modified photosensitizer Icy7, denoted LLI, significantly inhibits tumor growth of GC. LLI internalizes into MFC cells to generate ROS causing immunogenic cell death (ICD). Simultaneously, liposome-deliver Liproxstatin-1 effectively inhibits the ferroptosis of tumor neutrophils. LLI-based immunogenic PDT and neutrophil-targeting immunotherapy synergistically boost the anti-PD-1 treatment to elicit potent TME and systemic antitumor immune response with abscopal effects. In conclusion, LLI holds great potential for GC immunotherapy.

Cost-effectiveness of tumor-treating fields plus standard therapy for advanced non-small cell lung cancer progressed after platinum-based therapy in the United States

Background: Tumor treating fields (TTF) was first approved for treatment of glioblastoma. Recently, the LUNAR study demonstrated that TTF + standard therapy (ST) extended survival in patients with advanced non-small cell lung cancer (NSCLC). This primary objective of this study is to analyze the cost-effectiveness of this treatment from the United States healthcare payers' perspective. Methods: A 3-health-state Markov model was established to compare the cost-effectiveness of TTF + ST and that of ST alone. Clinical data were extracted from the LUNAR study, supplemented by additional cost and utility data obtained from publications or online sources. One-way sensitivity analysis, probabilistic sensitivity analysis, and scenario analysis were conducted. The willingness-to-pay (WTP) threshold per quality-adjusted life-years (QALYs) gained was set to $150,000. The main results include total costs, QALYs, incremental cost-effectiveness ratio (ICER) and incremental net monetary benefit (INMB). Subgroup analyses were conducted for two types of ST, including immune checkpoint inhibitor, and docetaxel. Results: During a 10-year time horizon, the costs of TTF + ST and ST alone were $431,207.0 and $128,125.9, and the QALYs were 1.809 and 1.124, respectively. The ICER of TTF + ST compared to ST was $442,732.7 per QALY, and the INMB was -$200,395.7 at the WTP threshold. The cost of TTF per month was the most influential factor in cost-effectiveness, and TTF + ST had a 0% probability of being cost-effective at the WTP threshold compared with ST alone. Conclusion: TTF + ST is not a cost-effective treatment for advanced NSCLC patients who progressed after platinum-based therapy from the perspective of the United States healthcare payers.

Celastrol Elicits Antitumor Effects through Inducing Immunogenic Cell Death and Downregulating PD-L1 in ccRCC

BACKGROUND

Targeting immunogenic cell death (ICD) is considered a promising therapeutic strategy for cancer. However, the commonly identified ICD inducers promote the expression of programmed cell death ligand 1 (PD-L1) in tumor cells, thus aiding them to evade the recognition and killing by the immune system. Therefore, the finding of novel ICD inducers to avoid enhanced PD-L1 expression is of vital significance for cancer therapy. Celastrol (CeT), a triterpene isolated from Tripterygium wilfordii Hook. F induces various forms of cell death to exert anti-cancer effects, which may make celastrol an attractive candidate as an inducer of ICD.

METHODS

In the present study, bioinformatics analysis was combined with experimental validation to explore the underlying mechanism by which CeT induces ICD and regulates PD-L1 expression in clear cell renal cell carcinoma (ccRCC).

RESULTS

The results showed that EGFR, IKBKB, PRKCQ and MAPK1 were the crucial targets for CeT-induced ICD, and only MAPK1 was an independent prognostic factor for the overall survival (OS) of ccRCC patients. In addition, CeT triggered autophagy and up-regulated the expressions of HMGB1 and CRT to induce ICD in 786-O cells in vitro. Importantly, CeT can down-regulate PD-L1 expression through activating autophagy. At the molecular level, CeT suppressed PD-L1 via the inhibition of MAPK1 expression. Immunologically, the core target of celastrol, MAPK1, was tightly correlated with CD8+ T cells and CD4+ T cells in ccRCC.

CONCLUSION

These findings indicate that CeT not only induces ICD but also suppresses PD-L1 by down-regulating MAPK1 expression, which will provide an attractive strategy for ccRCC immunotherapy.

Enhancing Cancer Chemo-Immunotherapy: Innovative Approaches for Overcoming Immunosuppression by Functional Nanomaterials

Chemotherapy is a critical modality in cancer therapy to combat malignant cell proliferation by directly attacking cancer cells and inducing immunogenic cell death, serving as a vital component of multi-modal treatment strategies for enhanced therapeutic outcomes. However, chemotherapy may inadvertently contribute to the immunosuppression of the tumor microenvironment (TME), inducing the suppression of antitumor immune responses, which can ultimately affect therapeutic efficacy. Chemo-immunotherapy, combining chemotherapy and immunotherapy in cancer treatment, has emerged as a ground-breaking approach to target and eliminate malignant tumors and revolutionize the treatment landscape, offering promising, durable responses for various malignancies. Notably, functional nanomaterials have substantially contributed to chemo-immunotherapy by co-delivering chemo-immunotherapeutic agents and modulating TME. In this review, recent advancements in chemo-immunotherapy are thus summarized to enhance treatment effectiveness, achieved by reversing the immunosuppressive TME (ITME) through the exploitation of immunotherapeutic drugs, or immunoregulatory nanomaterials. The effects of two-way immunomodulation and the causes of immunoaugmentation and suppression during chemotherapy are illustrated. The current strategies of chemo-immunotherapy to surmount the ITME and the functional materials to target and regulate the ITME are discussed and compared. The perspective on tumor immunosuppression reversal strategy is finally proposed.

Tumor treating fields for the treatment of glioblastoma: Current understanding and future perspectives

Background

This review focuses on the recently published evidence on tumor treating fields (TTFields) administered alone or in combination with locoregional and systemic options for treating glioblastoma (GBM) in the past ten years. The aim is to critically summarize the novelty and results obtained with this innovative tool, which is becoming part of the armamentarium of neurosurgeons and neuro-oncologists.

Methods

A comprehensive search and analysis were conducted on pivotal studies published in the past ten years. Furthermore, all completed clinical trials, whose results were published on clinicaltrials.gov, were examined and included in the present review, encompassing both recurrent (r) and newly diagnosed (n) GBM. Finally, an additional examination of the ongoing clinical trials was also conducted.

Results

Recent trials have shown promising results both in patients with nGBM and rGBM/progressive (rGBM), leading to Food and Drug Administration approval in selected patients and the Congress of Neurological Surgeons to include TTFields into current guidelines on the management of GBM (P100034/S001-029). Recently, different randomized trials have demonstrated promising results of TTFields in combination with standard treatment of n- and rGBM, especially when considering progression-free and overall survival, maintaining a low rate of mild to moderate adverse events.

Conclusion

Optimal outcomes were obtained in nGBM and progressive disease. A possible future refinement of TTFields could significantly impact the treatment of rGBM and the actual standard of care for GBM, given the better safety profile and survival effects.

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.

Role and clinical significance of immunogenic cell death biomarkers in chemoresistance and immunoregulation of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignancies in the whole world, with little improvement in the 5-year survival rate due to the occurrence of chemoresistance. With the increasing interests in tumor immune microenvironment, immunogenic cell death (ICD)-induced chemotherapy has shown promising results in enhancing sensitivity to immune checkpoint inhibitors (ICI) and improving the efficiency of tumor immunotherapy. This review summarizes the role of key ICD biomarkers and their underlying molecular mechanisms in HNSCC chemoresistance. The results showed that ICD initiation could significantly improve the survival and prognosis of patients. ICD and its biomarker could also serve as molecular markers for tumor diagnosis and prognosis. Moreover, key components of DAMPs including CALR, HGMB1, and ATP are involved in the regulation of HNSCC chemo-sensitivity, confirming that the key biomarkers of ICD can also be developed into new targets for regulating HNSCC chemoresistance. This review clearly illustrates the theoretical basis for the hypothesis that ICD biomarkers are therapeutic targets involved in HNSCC progression, chemoresistance, and even immune microenvironment regulation. The compilation and investigation may provide new insights into the molecular therapy of HNSCC.

Methods behind oncolytic virus-based DC vaccines in cancer: Toward a multiphase combined treatment strategy for Glioblastoma (GBM) patients

Glioblastoma (GBM) remains an orphan cancer disease with poor outcome. Novel treatment strategies are needed. Immunotherapy has several modes of action. The addition of active specific immunotherapy with dendritic cell vaccines resulted in improved overall survival of patients. Integration of DC vaccination within the first-line combined treatment became a challenge, and immunogenic cell death immunotherapy during chemotherapy was introduced. We used a retrospective analysis using real world data to evaluate the complex combined treatment, which included individualized multimodal immunotherapy during and after standard of care, and which required adaptations during treatment, and found a further improvement of overall survival. We also discuss the use of real world data as evidence. Novel strategies to move the field of individualized multimodal immunotherapy forward for GBM patients are reviewed.

Targeting TNFAIP2 induces immunogenic cell death and sensitizes glioblastoma multiforme to anti-PD-1 therapy

BACKGROUND

The efficacy of current immunotherapeutic strategies for patients with glioblastoma multiforme (GBM) remains unsatisfactory. The purpose of this study was to investigate the correlation between tumor necrosis factor alpha-induced protein 2 (TNFAIP2) and immunogenic cell death (ICD) in GBM, and to examine the effect of TNFAIP2 knockdown and anti-PD-1 combination treatment in a mouse glioma model.

METHODS

The CGGA and TCGA databases were used to explore the possible function of TNFAIP2 in GBM. Multiplex immunohistochemistry (mIHC) staining was performed to detect the immune infiltration of tissues. Western blot, quantitative real-time polymerase chain reaction (qRT-PCR), flow cytometry, and enzyme linked immunosorbent assay (ELISA) were utilized to detect the release of damage-associated molecular patterns (DAMPs) and the activation of the immune response. A mouse glioma model was applied to examine the induction of immune response.

RESULTS

In vitro and in vivo studies demonstrated that TNFAIP2 knockdown increased the surface exposure of calreticulin (CALR), heat shock protein 70 kDa (HSP70), and heat shock protein 90 kDa (HSP90) in GBM cell lines, thereby inducing immunogenic cell death (ICD). Importantly, the study found that TNFAIP2 knockdown in combination with anti-PD-1 therapy significantly improved the overall survival of glioma in a mouse model.

CONCLUSIONS

TNFAIP2 knockdown induces ICD by downregulating TNFAIP2 in GBM. In addition, TNFAIP2 knockdown sensitized glioma to anti-PD-1 therapy. Hence, targeting TNFAIP2 alone or in combination with anti-PD-1 therapy may be a potential strategy for GBM treatment through ICD.

Tumor Treating Fields therapy with standard systemic therapy versus standard systemic therapy alone in metastatic non-small-cell lung cancer following progression on or after platinum-based therapy (LUNAR): a randomised, open-label, pivotal phase 3 study

BACKGROUND

Tumor Treating Fields (TTFields) are electric fields that disrupt processes critical for cancer cell survival, leading to immunogenic cell death and enhanced antitumour immune response. In preclinical models of non-small-cell lung cancer, TTFields amplified the effects of chemotherapy and immune checkpoint inhibitors. We report primary results from a pivotal study of TTFields therapy in metastatic non-small-cell lung cancer.

METHODS

This randomised, open-label, pivotal phase 3 study recruited patients at 130 sites in 19 countries. Participants were aged 22 years or older with metastatic non-small-cell lung cancer progressing on or after platinum-based therapy, with squamous or non-squamous histology and ECOG performance status of 2 or less. Previous platinum-based therapy was required, but no restriction was placed on the number or type of previous lines of systemic therapy. Participants were randomly assigned (1:1) to TTFields therapy and standard systemic therapy (investigator's choice of immune checkpoint inhibitor [nivolumab, pembrolizumab, or atezolizumab] or docetaxel) or standard therapy alone. Randomisation was performed centrally using variable blocked randomisation and an interactive voice-web response system, and was stratified by tumour histology, treatment, and region. Systemic therapies were dosed according to local practice guidelines. TTFields therapy (150 kHz) was delivered continuously to the thoracic region with the recommendation to achieve an average of at least 18 h/day device usage. The primary endpoint was overall survival in the intention-to-treat population. The safety population included all patients who received any study therapy and were analysed according to the actual treatment received. The study is registered with ClinicalTrials.gov, NCT02973789.

FINDINGS

Between Feb 13, 2017, and Nov 19, 2021, 276 patients were enrolled and randomly assigned to receive TTFields therapy with standard therapy (n=137) or standard therapy alone (n=139). The median age was 64 years (IQR 59-70), 178 (64%) were male and 98 (36%) were female, 156 (57%) had non-squamous non-small-cell lung cancer, and 87 (32%) had received a previous immune checkpoint inhibitor. Median follow-up was 10·6 months (IQR 6·1-33·7) for patients receiving TTFields therapy with standard therapy, and 9·5 months (0·1-32·1) for patients receiving standard therapy. Overall survival was significantly longer with TTFields therapy and standard therapy than with standard therapy alone (median 13·2 months [95% CI 10·3-15·5] vs 9·9 months [8·1-11·5]; hazard ratio [HR] 0·74 [95% CI 0·56-0·98]; p=0·035). In the safety population (n=267), serious adverse events of any cause were reported in 70 (53%) of 133 patients receiving TTFields therapy plus standard therapy and 51 (38%) of 134 patients receiving standard therapy alone. The most frequent grade 3-4 adverse events were leukopenia (37 [14%] of 267), pneumonia (28 [10%]), and anaemia (21 [8%]). TTFields therapy-related adverse events were reported in 95 (71%) of 133 patients; these were mostly (81 [85%]) grade 1-2 skin and subcutaneous tissue disorders. There were three deaths related to standard therapy (two due to infections and one due to pulmonary haemorrhage) and no deaths related to TTFields therapy.

INTERPRETATION

TTFields therapy added to standard therapy significantly improved overall survival compared with standard therapy alone in metastatic non-small-cell lung cancer after progression on platinum-based therapy without exacerbating systemic toxicities. These data suggest that TTFields therapy is efficacious in metastatic non-small-cell lung cancer and should be considered as a treatment option to manage the disease in this setting.

FUNDING

Novocure.

A review of tumor treating fields (TTFields): advancements in clinical applications and mechanistic insights

BACKGROUND

Tumor Treating Fields (TTFields) is a non-invasive modality for cancer treatment that utilizes a specific sinusoidal electric field ranging from 100 kHz to 300 kHz, with an intensity of 1 V/cm to 3 V/cm. Its purpose is to inhibit cancer cell proliferation and induce cell death. Despite promising outcomes from clinical trials, TTFields have received FDA approval for the treatment of glioblastoma multiforme (GBM) and malignant pleural mesothelioma (MPM). Nevertheless, global acceptance of TTFields remains limited. To enhance its clinical application in other types of cancer and gain a better understanding of its mechanisms of action, this review aims to summarize the current research status by examining existing literature on TTFields' clinical trials and mechanism studies.

CONCLUSIONS

Through this comprehensive review, we seek to stimulate novel ideas and provide physicians, patients, and researchers with a better comprehension of the development of TTFields and its potential applications in cancer treatment.

Association of Tumor Treating Fields (TTFields) therapy with survival in newly diagnosed glioblastoma: a systematic review and meta-analysis

PURPOSE

Tumor Treating Fields (TTFields) therapy, an electric field-based cancer treatment, became FDA-approved for patients with newly diagnosed glioblastoma (GBM) in 2015 based on the randomized controlled EF-14 study. Subsequent approvals worldwide and increased adoption over time have raised the question of whether a consistent survival benefit has been observed in the real-world setting, and whether device usage has played a role.

METHODS

We conducted a literature search to identify clinical studies evaluating overall survival (OS) in TTFields-treated patients. Comparative and single-cohort studies were analyzed. Survival curves were pooled using a distribution-free random-effects method.

RESULTS

Among nine studies, seven (N = 1430 patients) compared the addition of TTFields therapy to standard of care (SOC) chemoradiotherapy versus SOC alone and were included in a pooled analysis for OS. Meta-analysis of comparative studies indicated a significant improvement in OS for patients receiving TTFields and SOC versus SOC alone (HR: 0.63; 95% CI 0.53-0.75; p < 0.001). Among real-world post-approval studies, the pooled median OS was 22.6 months (95% CI 17.6-41.2) for TTFields-treated patients, and 17.4 months (95% CI 14.4-21.6) for those not receiving TTFields. Rates of gross total resection were generally higher in the real-world setting, irrespective of TTFields use. Furthermore, for patients included in studies reporting data on device usage (N = 1015), an average usage rate of ≥ 75% was consistently associated with prolonged survival (p < 0.001).

CONCLUSIONS

Meta-analysis of comparative TTFields studies suggests survival may be improved with the addition of TTFields to SOC for patients with newly diagnosed GBM.

Effectiveness of tumor‑treating fields to reduce the proliferation and migration of liposarcoma cell lines

Liposarcoma (LPS) is a rare type of soft tissue sarcoma that constitutes 20% of all sarcoma cases in adults. Effective therapeutic protocols for human LPS are not well-defined. Tumor-treating fields (TTFields) are a novel and upcoming field for antitumor therapy. TTFields combined with chemoradiotherapy have proven to be more effective than TTFields combined with radiotherapy or chemotherapy alone. The present study aimed to assess the effectiveness of TTFields in inhibiting cell proliferation and viability for the anticancer treatment of LPS. The present study used TTFields (frequency, 150 kHz; intensity, 1.0 V/cm) to treat two LPS cell lines (94T778 and SW872) and analyzed the antitumor effects. According to trypan blue and MTT assay results, TTFields markedly reduced the viability and proliferation of LPS cell lines along with the formation of colonies in three-dimensional culture. Based on the Transwell chamber assay, TTFields treatment also markedly reduced the migration of LPS cells. Furthermore, as shown by the higher activation of caspase-3 in the Caspase-3 activity assay and the results of the reactive oxygen species (ROS) assay, TTFields increased the formation of ROS in the cells and enhanced the proportion of apoptotic cells. The present study also investigated the inhibitory effect of TTFields in combination with doxorubicin (DOX) on the migratory capacity of tumor cells. The results demonstrated that TTFields treatment synergistically induced the ROS-induced apoptosis of LPS cancer cell lines and inhibited their migratory behavior. In conclusion, the present study demonstrated the potential of TTFields in improving the sensitivity of LPS cancer cells, which may lay the foundation for future clinical trials of this combination treatment strategy.

Pulsed Electric Fields in Oncology: A Snapshot of Current Clinical Practices and Research Directions from the 4th World Congress of Electroporation

The 4th World Congress of Electroporation (Copenhagen, 9-13 October 2022) provided a unique opportunity to convene leading experts in pulsed electric fields (PEF). PEF-based therapies harness electric fields to produce therapeutically useful effects on cancers and represent a valuable option for a variety of patients. As such, irreversible electroporation (IRE), gene electrotransfer (GET), electrochemotherapy (ECT), calcium electroporation (Ca-EP), and tumour-treating fields (TTF) are on the rise. Still, their full therapeutic potential remains underappreciated, and the field faces fragmentation, as shown by parallel maturation and differences in the stages of development and regulatory approval worldwide. This narrative review provides a glimpse of PEF-based techniques, including key mechanisms, clinical indications, and advances in therapy; finally, it offers insights into current research directions. By highlighting a common ground, the authors aim to break silos, strengthen cross-functional collaboration, and pave the way to novel possibilities for intervention. Intriguingly, beyond their peculiar mechanism of action, PEF-based therapies share technical interconnections and multifaceted biological effects (e.g., vascular, immunological) worth exploiting in combinatorial strategies.

An implantable ionic therapeutic platform for photodynamic therapy with wireless capacitive power transfer

In this work, we describe the development of an implantable ionic device that can deliver a spatially targeted light source to tumor tissues in a controllable manner. The motivation behind our approach is to overcome certain limitations of conventional approaches where light is delivered from the outside of the body and only achieves low penetration depths. Also, to avoid the issues that come from the periodic need to replace the device's battery, we utilize a wireless power transfer system synchronized with light operation in an implantable structure. In our testing of this implanted, soft ionic, gel-based device that receives power wirelessly, we were able to clearly observe its capability to effectively deliver light in a harmonious and stable configuration to adjacent tissues. This approach reduces the mechanical inconsistencies seen in conventional systems that are induced by mismatches between the mechanical strength of conventional metallic components and that of biological tissues. The light delivering performance of our device was studied in depth under the various conditions set by adjusting the area of the gel receivers, the ion concentration and the ion types used in the gel components. The enhanced antitumor effects of our device were observed through in vitro cell tests, in comparison with treatments using the conventional approach of using direct light from outside the body. Full encapsulation using biocompatible elastomers enables our device to provide good functional stability, while implantation for about 3 weeks in the in vivo model showed the effective targeted photodynamic treatments made possible by our approach. Our advanced approach of designing the implantable platform based on ionic gel components allows us to iteratively irradiate a target with light whenever required, making the technology particularly suited to long-term treatment of residual tumors while facilitating further practical and clinical development.

Characteristics and management of tumor treating fields-related dermatological complications in patients with glioblastoma

Tumor treating fields (TTFields) is a novel approved modality for the treatment of glioblastoma (GBM) exhibiting a satisfactory effect. Although TTFields has shown considerable safety for the normal brain, dermatological adverse events (DAEs) often occur during therapy. However, studies focused on the identification and management of DAEs are rare. The clinical data and photos of skin lesions from 9 patients with GBM were retrospectively analyzed, and the types and grades of individual scalp dermatitis were evaluated based on the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v 5.0). Adherence and safety were also evaluated on the basis of the device monitoring data. Eight patients (88.9%) exhibited grade 1 or grade 2 CTCAE DAEs, all of whom were cured after interventions. The adherence was >90%, with no relevant safety events reported. Finally, a guideline for preventing DAEs in patients with GBM was proposed. The identification and management of TTFields-related DAEs is necessary and urgent in patients with GBM. Timely interventions of DAEs will help to improve the adherence and quality of life of patients, which ultimately improves prognosis. The proposed guideline for preventing DAEs in patients with GBM assists in the management of healthcare providers and may avoid dermatologic complications.

Endoplasmic Reticulum Stress in the Brain Tumor Immune Microenvironment

Immunotherapy has emerged as a powerful strategy for halting cancer progression. However, primary malignancies affecting the brain have been exempt to this success. Indeed, brain tumors continue to portend severe morbidity and remain a globally lethal disease. Extensive efforts have been directed at understanding how tumor cells survive and propagate within the unique microenvironment of the central nervous system (CNS). Cancer genetic aberrations and metabolic abnormalities provoke a state of persistent endoplasmic reticulum (ER) stress that in turn promotes tumor growth, invasion, therapeutic resistance, and the dynamic reprogramming of the infiltrating immune cells. Consequently, targeting ER stress is a potential therapeutic approach. In this work, we provide an overview of how ER stress response is advantageous to brain tumor development, discuss the significance of ER stress in governing antitumor immunity, and put forth therapeutic strategies of regulating ER stress to augment the effect of immunotherapy for primary CNS tumors.

Therapeutic potential of tumor treating fields for malignant brain tumors

BACKGROUND

Malignant brain tumors are among the most threatening diseases of the central nervous system, and despite increasingly updated treatments, the prognosis has not been improved. Tumor treating fields (TTFields) are an emerging approach in cancer treatment using intermediate-frequency and low-intensity electric field and can lead to the development of novel therapeutic options.

RECENT FINDINGS

A series of biological processes induced by TTFields to exert anti-cancer effects have been identified. Recent studies have shown that TTFields can alter the bioelectrical state of macromolecules and organelles involved in cancer biology. Massive alterations in cancer cell proteomics and transcriptomics caused by TTFields were related to cell biological processes as well as multiple organelle structures and activities. This review addresses the mechanisms of TTFields and recent advances in the application of TTFields therapy in malignant brain tumors, especially in glioblastoma (GBM).

CONCLUSIONS

As a novel therapeutic strategy, TTFields have shown promising results in many clinical trials, especially in GBM, and continue to evolve. A growing number of patients with malignant brain tumors are being enrolled in ongoing clinical studies demonstrating that TTFields-based combination therapies can improve treatment outcomes.

Ion channels as molecular targets of glioblastoma electrotherapy

Therapies with weak, non-ionizing electromagnetic fields comprise FDA-approved treatments such as Tumor Treating Fields (TTFields) that are used for adjuvant therapy of glioblastoma. In vitro data and animal models suggest a variety of biological TTFields effects. In particular, effects ranging from direct tumoricidal, radio- or chemotherapy-sensitizing, metastatic spread-inhibiting, up to immunostimulation have been described. Diverse underlying molecular mechanisms, such as dielectrophoresis of cellular compounds during cytokinesis, disturbing the formation of the spindle apparatus during mitosis, and perforating the plasma membrane have been proposed. Little attention, however, has been paid to molecular structures that are predestinated to percept electromagnetic fields-the voltage sensors of voltage-gated ion channels. The present review article briefly summarizes the mode of action of voltage sensing by ion channels. Moreover, it introduces into the perception of ultra-weak electric fields by specific organs of fishes with voltage-gated ion channels as key functional units therein. Finally, this article provides an overview of the published data on modulation of ion channel function by diverse external electromagnetic field protocols. Combined, these data strongly point to a function of voltage-gated ion channels as transducers between electricity and biology and, hence, to voltage-gated ion channels as primary targets of electrotherapy.

Individualized Multimodal Immunotherapy for Adults with IDH1 Wild-Type GBM: A Single Institute Experience

Synergistic activity between maintenance temozolomide (TMZm) and individualized multimodal immunotherapy (IMI) during/after first-line treatment has been suggested to improve the overall survival (OS) of adults with IDH1 wild-type MGMT promoter-unmethylated (unmeth) GBM. We expand the data and include the OS of MGMT promoter-methylated (meth) adults with GBM. Unmeth (10 f, 18 m) and meth (12 f, 10 m) patients treated between 27 May 2015 and 1 January 2022 were analyzed retrospectively. There were no differences in age (median: 48 y) or Karnofsky performance index (median: 80). The IMI consisted of 5-day immunogenic cell death (ICD) therapies during TMZm: Newcastle disease virus (NDV) bolus injections and sessions of modulated electrohyperthermia (mEHT); subsequent active specific immunotherapy: dendritic cell (DC) vaccines plus modulatory immunotherapy; and maintenance ICD therapy. There were no differences in the number of vaccines (median: 2), total number of DCs (median: 25.6 × 10⁶), number of NDV injections (median: 31), and number of mEHT sessions (median: 28) between both groups. The median OS of 28 unmeth patients was 22 m (2y-OS: 39%), confirming previous results. OS of 22 meth patients was significantly better (p = 0.0414) with 38 m (2y-OS: 81%). There were no major treatment-related adverse reactions. The addition of IMI during/after standard of care should be prospectively explored.

Tumor Treating Fields (TTFields) Therapy Concomitant with Taxanes for Cancer Treatment

Non-small cell lung cancer, ovarian cancer, and pancreatic cancer all present with high morbidity and mortality. Systemic chemotherapies have historically been the cornerstone of standard of care (SOC) regimens for many cancers, but are associated with systemic toxicity. Multimodal treatment combinations can help improve patient outcomes; however, implementation is limited by additive toxicities and potential drug-drug interactions. As such, there is a high unmet need to develop additional therapies to enhance the efficacy of SOC treatments without increasing toxicity. Tumor Treating Fields (TTFields) are electric fields that exert physical forces to disrupt cellular processes critical for cancer cell viability and tumor progression. The therapy is locoregional and is delivered noninvasively to the tumor site via a portable medical device that consists of field generator and arrays that are placed on the patient's skin. As a noninvasive treatment modality, TTFields therapy-related adverse events mainly consist of localized skin reactions, which are manageable with effective acute and prophylactic treatments. TTFields selectively target cancer cells through a multi-mechanistic approach without affecting healthy cells and tissues. Therefore, the application of TTFields therapy concomitant with other cancer treatments may lead to enhanced efficacy, with low risk of further systemic toxicity. In this review, we explore TTFields therapy concomitant with taxanes in both preclinical and clinical settings. The summarized data suggest that TTFields therapy concomitant with taxanes may be beneficial in the treatment of certain cancers.

Safety and efficacy of tumour-treating fields (TTFields) therapy for newly diagnosed glioblastoma in Japanese patients using the Novo-TTF System: a prospective post-approval study

BACKGROUND

Tumour-treating fields therapy is a locoregional, anti-cancer treatment. Efficacy and safety of tumour-treating fields therapy in adults with newly diagnosed glioblastoma were demonstrated in the pivotal phase 3 EF-14 study (NCT00916409). Here, we report post-approval data of tumour-treating fields therapy in Japanese patients with newly diagnosed glioblastoma.

METHODS

Unsolicited post-marketing surveillance data from Japanese patients with newly diagnosed glioblastoma treated with tumour-treating fields therapy (December 2016-June 2020) were retrospectively analysed. The primary endpoints were skin, neurological and psychiatric adverse events. The secondary endpoints were 1- and 2-year overall survival rates, and the 6-month progression-free survival. adverse events were analysed using MedDRA v24.0. The overall survival and progression-free survival were assessed using the Kaplan-Meier survival analysis (log-rank testing). The Cox proportional hazard regression analyses were also performed.

RESULTS

Forty patients with newly diagnosed glioblastoma were enrolled (62.5% male; median age 59 years; median baseline Karnofsky Performance Scale score 90). The most common tumour-treating-fields-therapy-related adverse event was beneath-array local skin reaction (60% of patients). The adverse events were mostly mild to moderate in severity. Neurological disorders were observed in 2.5% patients (one patient reported dysesthesia). No psychiatric disorders were reported. The 1- and 2-year overall survival rates were 77.9% (95% CI 60.6-88.3) and 53.6% (35.5-68.7%), respectively. The 6-month progression-free survival was 77.5% (61.2-87.6%). These survival rates compare favourably with those in the EF-14 trial (1- and 2-year overall survival rates: 73% [69-77%] and 43% [39-48%], respectively; 6-month progression-free survival rate: 56% (51-61%).

CONCLUSION

This post-approval, real-world evidence study revealed no new safety signals and suggests the safety and efficacy of tumour-treating fields therapy in Japanese patients with newly diagnosed glioblastoma.

Novel immunogenic cell death-related risk signature to predict prognosis and immune microenvironment in lung adenocarcinoma

PURPOSE

Immunogenic cell death (ICD) is a type of regulated cell death (RCD) which was discovered to activate adaptive immunity. To date, the effect of ICD on lung adenocarcinoma (LUAD) remains unclear. In this research, we will study the role of ICD-related genes (ICDG) in LUAD.

METHODS

RNA sequencing and clinical data were gathered from TCGA-LUAD cohorts and GEO database. Using unsupervised cluster analysis, three clusters were identified with distinctive immune characteristics and significant overall survival based on 18 ICDG. Using LASSO Cox regression, three genes were identified and used to construct the prognosis signature. The association between the 3-ICDG risk signature and immune microenvironment analysis, somatic mutation, and enriched molecular pathways was investigated.

RESULTS

Consensus clustering separated the LUAD samples into three clusters (ICDcluster A, B and C), and ICDcluster B had the best prognosis. Different TME cell infiltration characteristics and biological behavior were found in three ICD clusters. Prognostic risk model was contrasted based on the 3 best prognostic ICD-related genes. Subsequently, vitro experiments verified the above analysis results. The high-risk group showed a poor prognosis and enrichment of cancer promoting signal pathway. Multivariate analysis indicated that this 3-ICDG prognostic model might be an accurate prediction parameter for LUAD. Moreover, conducting immune related analysis, we found that the 3-ICDG risk signature was characterized by an immune-active subtype on account of the high infiltration of immune-active cells.

CONCLUSION

This study expands our cognition of ICD in LUAD microenvironment, excavated prognostic biomarkers, and provided potential value for guiding immunotherapy and chemotherapy.

Engineering the Tumor Immune Microenvironment through Minimally Invasive Interventions

The tumor microenvironment (TME) is a unique landscape that poses several physical, biochemical, and immune barriers to anti-cancer therapies. The rapidly evolving field of immuno-engineering provides new opportunities to dismantle the tumor immune microenvironment by efficient tumor destruction. Systemic delivery of such treatments can often have limited local effects, leading to unwanted offsite effects such as systemic toxicity and tumor resistance. Interventional radiologists use contemporary image-guided techniques to locally deliver these therapies to modulate the immunosuppressive TME, further accelerating tumor death and invoking a better anti-tumor response. These involve local therapies such as intratumoral drug delivery, nanorobots, nanoparticles, and implantable microdevices. Physical therapies such as photodynamic therapy, electroporation, hyperthermia, hypothermia, ultrasound therapy, histotripsy, and radiotherapy are also available for local tumor destruction. While the interventional radiologist can only locally manipulate the TME, there are systemic offsite recruitments of the immune response. This is known as the abscopal effect, which leads to more significant anti-tumoral downstream effects. Local delivery of modern immunoengineering methods such as locoregional CAR-T therapy combined with immune checkpoint inhibitors efficaciously modulates the immunosuppressive TME. This review highlights the various advances and technologies available now to change the TME and revolutionize oncology from a minimally invasive viewpoint.

Research progress in inducing immunogenic cell death of tumor cells

Immunogenic cell death (ICD) is a regulated cell death (RCD) pathway. In response to physical and chemical signals, tumor cells activate specific signaling pathways that stimulate stress responses in the endoplasmic reticulum (ER) and expose damage-associated molecular patterns (DAMPs), which promote antitumor immune responses. As a result, the tumor microenvironment is altered, and many tumor cells are killed. The ICD response in tumor cells requires inducers. These inducers can be from different sources and contribute to the development of the ICD either indirectly or directly. The combination of ICD inducers with other tumor treatments further enhances the immune response in tumor cells, and more tumor cells are killed; however, it also produces side effects of varying severity. New induction methods based on nanotechnology improve the antitumor ability and significantly reduces side effects because they can target tumor cells precisely. In this review, we introduce the characteristics and mechanisms of ICD responses in tumor cells and the DAMPs associated with ICD responses, summarize the current methods of inducing ICD response in tumor cells in five distinct categories: chemical sources, physical sources, pathogenic sources, combination therapies, and innovative therapies. At the same time, we introduce the limitations of current ICD inducers and make a summary of the use of ICD responses in clinical trials. Finally, we provide an outlook on the future of ICD inducer development and provide some constructive suggestions.

Tumor Treating Fields (TTFields) Concomitant with Immune Checkpoint Inhibitors Are Therapeutically Effective in Non-Small Cell Lung Cancer (NSCLC) In Vivo Model

Tumor Treating Fields (TTFields) are electric fields that exert physical forces to disrupt cellular processes critical for cancer cell viability and tumor progression. TTFields induce anti-mitotic effects through the disruption of the mitotic spindle and abnormal chromosome segregation, which trigger several forms of cell death, including immunogenic cell death (ICD). The efficacy of TTFields concomitant with anti-programmed death-1 (anti-PD-1) treatment was previously shown in vivo and is currently under clinical investigation. Here, the potential of TTFields concomitant with anti- PD-1/anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) or anti-programmed death-ligand 1 (anti-PD-L1) immune checkpoint inhibitors (ICI) to improve therapeutic efficacy was examined in lung tumor-bearing mice. Increased circulating levels of high mobility group box 1 protein (HMGB1) and elevated intratumoral levels of phosphorylated eukaryotic translation initiation factor 2α (p-eIF2α) were found in the TTFields-treated mice, indicative of ICD induction. The concomitant application of TTFields and ICI led to a significant decrease in tumor volume as compared to all other groups. In addition, significant increases in the number of tumor-infiltrating immune cells, specifically cytotoxic T-cells, were observed in the TTFields plus anti-PD-1/anti-CTLA-4 or anti-PD-L1 groups. Correspondingly, cytotoxic T-cells isolated from these tumors showed higher levels of IFN-γ production. Collectively, these results suggest that TTFields have an immunoactivating role that may be leveraged for concomitant treatment with ICI to achieve better tumor control by enhancing antitumor immunity.

Research on application of tumor treating fields in glioblastoma: A bibliometric and visual analysis

Background

Glioblastoma, one of the common tumors of the central nervous system (CNS), is prone to recurrence even after standard treatment protocols. As an innovative physiotherapy method emerging in recent years, the tumor treating fields (TTFields) technique has been approved for the treatment of glioblastoma due to its non-invasive and portable features. The purpose of this study is to visualize and analyze the scientific results and research trends in TTFields therapy for glioblastoma.

Methods

Publications related to TTFields therapy for glioblastoma were searched in the Web of Science Core Collection (WoSCC) database in September 2022. A bibliometric and visual analysis of publications in this field was performed mainly using CiteSpace and R software for country/region, author, journal, reference and keyword.

Results

A total of 618 publications in this field were retrieved, and 248 were finally obtained according to the search criteria, including 159 articles (64.11%) and 89 reviews (37.89%). The cumulative number of publications increased year by year, with an average growth rate (AGR) of 28.50%. The test results of Pearson correlation coefficient showed a high positive correlation between publications and citations (r=0.937, p&lt;0.001). The USA had the largest number of publications (123, 49.60%), followed by Germany (32, 12.90%) and China (30, 12.10%). As for the country/region collaborations, the USA cooperated most closely with other countries/regions, followed by Germany and China. The degree of collaboration (DC) between countries/regions was 25.81%. The institutions with the largest number of publications were Tel Aviv Univ (10), Harvard Med Sch (10) and Novocure Ltd (10). Moreover, Wong E (18) possessed the greatest number of publications, followed by Weinberg U (11) and Kirson E (10). The DC between authors was 97.58%. STUPP R (236) was the most cited author followed by KIRSON ED (164) and GILADI M (104). JOURNAL OF NEURO-ONCOLOGY (22) was the journal with the largest number of published publications (75), followed by FRONTIERS IN ONCOLOGY (15) and CANCERS (13). The top 10 keywords that occurred frequently included glioblastoma (156), tumor treating field (152), temozolomide (134), randomized phase III (48), brain (46), survivor (46), cancer (44), trial (42), alternating electric field (42) and radiotherapy (36). Furthermore, cluster analysis was performed on the basis of keyword co-occurrence, and finally 15 clusters were formed to determine the current research status and future development trend of TTFields therapy for glioblastoma.

Conclusion

TTFields has been increasingly known as the fourth novel physical anti-tumor therapy in addition to surgery, radiotherapy and anti-tumor drugs. Cooperation and communication between countries/regions need to be enhanced in future research. Several studies have demonstrated the therapeutic potential of TTFields in glioma, and its application alone or in combination with other treatments has become a current research hotspot.

Autophagy promotes directed migration of HUVEC in response to electric fields through the ROS/SIRT1/FOXO1 pathway

Endogenous electric fields (EFs) have been confirmed to facilitate angiogenesis through guiding directional migration of endothelial cells (ECs), but the underlying mechanisms remain obscure. Recent studies suggest that the directed migration of ECs in angiogenesis is correlated with autophagy, and the latter of which could be augmented by EFs. We hypothesize that autophagy may participate in the EFs-guided migration of ECs during angiogenesis. Herein, we showed that EFs induced human umbilical vein endothelial cells (HUVEC) migration toward the cathode with enhanced autophagy. Genetic ablation of autophagy by silencing the autophagy-related gene (Atg) 5 abolished the EFs-directed migration of HUVEC, indicating that autophagy is definitely required for EFs-guided migration of cells. Mechanistically, we identified the intracellular reactive oxygen species (ROS) as a crucial mediator in EFs-triggered autophagy through augmenting the silencing information regulator 2 related enzyme1 (SIRT1)/forkhead box protein O1 (FOXO1) signaling. Either ROS scavenging or SIRT1 knockdown eliminated the EFs-triggered autophagy in HUVEC. Further study showed that SIRT1 promoted FOXO1 deacetylation, facilitating its nuclear accumulation and transcriptional activity, and thereby activating autophagy in EFs-treated HUVECs. In conclusion, our study demonstrated a pivotal role for autophagy in EFs-induced directed migration of HUVECs through the ROS/SIRT1/FOXO1 pathway, and provided a novel theoretical foundation for angiogenesis.

The Mechanisms of Action of Tumor Treating Fields

Tumor treating fields (TTFields), a new modality of cancer treatment, are electric fields transmitted transdermally to tumors. The FDA has approved TTFields for the treatment of glioblastoma multiforme and mesothelioma, and they are currently under study in many other cancer types. While antimitotic effects were the first recognized biological anticancer activity of TTFields, data have shown that tumor treating fields achieve their anticancer effects through multiple mechanisms of action. TTFields therefore have the ability to be useful for many cancer types in combination with many different treatment modalities. Here, we review the current understanding of TTFields and their mechanisms of action.

The schemes, mechanisms and molecular pathway changes of Tumor Treating Fields (TTFields) alone or in combination with radiotherapy and chemotherapy

Tumor Treating Fields (TTFields) is a physical therapy that uses moderate frequency (100–300 kHz) and low-intensity (1–3 V/cm) alternating electric fields to inhibit tumors. Currently, the Food and Drug Administration approves TTFields for treating recurrent or newly diagnosed glioblastoma (GBM) and malignant pleural mesothelioma (MPM). The classical mechanism of TTFields is mitotic inhibition by hindering the formation of tubulin and spindle. In addition, TTFields inhibits cell proliferation, invasion, migration and induces cell death, such as apoptosis, autophagy, pyroptosis, and cell cycle arrest. Meanwhile, it regulates immune function and changes the permeability of the nuclear membrane, cell membrane, and blood-brain barrier. Based on the current researches on TTFields in various tumors, this review comprehensively summarizes the in-vitro effects, changes in pathways and molecules corresponding to relevant parameters of TTFields (frequency, intensity, and duration). In addition, radiotherapy and chemotherapy are common tumor treatments. Thus, we also pay attention to the sequence and dose when TTFields combined with radiotherapy or chemotherapy. TTFields has inhibitory effects in a variety of tumors. The study of TTFields mechanism is conducive to subsequent research. How to combine common tumor therapy such as radiotherapy and chemotherapy to obtain the maximum benefit is also a problem that’s worthy of our attention.

Anti-cancer mechanisms of action of therapeutic alternating electric fields (tumor treating fields [TTFields])

Despite improved survival outcomes across many cancer types, the prognosis remains grim for certain solid organ cancers including glioblastoma and pancreatic cancer. Invariably in these cancers, the control achieved by time-limited interventions such as traditional surgical resection, radiation therapy, and chemotherapy is short-lived. A new form of anti-cancer therapy called therapeutic alternating electric fields (AEFs) or tumor treating fields (TTFields) has been shown, either by itself or in combination with chemotherapy, to have anti-cancer effects that translate to improved survival outcomes in patients. Although the pre-clinical and clinical data are promising, the mechanisms of TTFields are not fully elucidated. Many investigations are underway to better understand how and why TTFields is able to selectively kill cancer cells and impede their proliferation. The purpose of this review is to summarize and discuss the reported mechanisms of action of TTFields from pre-clinical studies (both in vitro and in vivo). An improved understanding of how TTFields works will guide strategies focused on the timing and combination of TTFields with other therapies, to further improve survival outcomes in patients with solid organ cancers.

Tumor-Treating Fields in Glioblastomas: Past, Present, and Future

Simple Summary

Glioblastoma (GBM) is the most common malignant primary brain tumor. Although the standard of care, including maximal resection, concurrent radiotherapy with temozolomide (TMZ), and adjuvant TMZ, has largely improved the prognosis of these patients, the 5-year survival rate is still < 10%. Tumor-treating fields (TTFields), a noninvasive anticancer therapeutic modality, has been rising as a fourth treatment option for GBMs, as confirmed by recent milestone large-scale phase 3 randomized trials and subsequent real-world data, elongating patient overall survival from 16 months to 21 months. However, the mechanisms of antitumor efficacy, its clinical safety, and potential benefits when combined with other treatment modalities are far from completely elucidated. As an increasing number of studies have recently been published on this topic, we conducted this updated, comprehensive review to establish an objective understanding of the mechanism of action, efficacy, safety, clinical concerns, and future perspectives of TTFields.

Abstract

Tumor-treating fields (TTFields), a noninvasive and innovative therapeutic approach, has emerged as the fourth most effective treatment option for the management of glioblastomas (GBMs), the most deadly primary brain cancer. According to on recent milestone randomized trials and subsequent observational data, TTFields therapy leads to substantially prolonged patient survival and acceptable adverse events. Clinical trials are ongoing to further evaluate the safety and efficacy of TTFields in treating GBMs and its biological and radiological correlations. TTFields is administered by delivering low-intensity, intermediate-frequency, alternating electric fields to human GBM function through different mechanisms of action, including by disturbing cell mitosis, delaying DNA repair, enhancing autophagy, inhibiting cell metabolism and angiogenesis, and limiting cancer cell migration. The abilities of TTFields to strengthen intratumoral antitumor immunity, increase the permeability of the cell membrane and the blood–brain barrier, and disrupt DNA-damage-repair processes make it a promising therapy when combined with conventional treatment modalities. However, the overall acceptance of TTFields in real-world clinical practice is still low. Given that increasing studies on this promising topic have been published recently, we conducted this updated review on the past, present, and future of TTFields in GBMs.