Tumor treating fields and maintenance temozolomide for newly-diagnosed glioblastoma: a cost-effectiveness study

Principles in the Management of Glioblastoma

Glioblastoma, the most aggressive and common malignant primary brain tumour, is characterized by infiltrative growth, abundant vascularization, and aggressive clinical evolution. Patients with glioblastoma often face poor prognoses, with a median survival of approximately 15 months. Technological progress and the subsequent improvement in understanding the pathophysiology of these tumours have not translated into significant achievements in therapies or survival outcomes for patients. Progress in molecular profiling has yielded new omics data for a more refined classification of glioblastoma. Several typical genetic and epigenetic alterations in glioblastoma include mutations in genes regulating receptor tyrosine kinase (RTK)/rat sarcoma (RAS)/phosphoinositide 3-kinase (PI3K), p53, and retinoblastoma protein (RB) signalling, as well as mutation of isocitrate dehydrogenase (IDH), methylation of O6-methylguanine-DNA methyltransferase (MGMT), amplification of epidermal growth factor receptor vIII, and codeletion of 1p/19q. Certain microRNAs, such as miR-10b and miR-21, have also been identified as prognostic biomarkers. Effective treatment options for glioblastoma are limited. Surgery, radiotherapy, and alkylating agent chemotherapy remain the primary pillars of treatment. Only promoter methylation of the gene MGMT predicts the benefit from alkylating chemotherapy with temozolomide and it guides the choice of first-line treatment in elderly patients. Several targeted strategies based on tumour-intrinsic dominant signalling pathways and antigenic tumour profiles are under investigation in clinical trials. This review explores the potential genetic and epigenetic biomarkers that could be deployed as analytical tools in the diagnosis and prognostication of glioblastoma. Recent clinical advancements in treating glioblastoma are also discussed, along with the potential of liquid biopsies to advance personalized medicine in the field of glioblastoma, highlighting the challenges and promises for the future.

Real-world cost- effectiveness analysis: Tumor Treating Fields for newly diagnosed glioblastoma in China

BACKGROUND

Glioblastoma (GBM) stands as the most aggressive and prevalent primary brain malignancy. Tumor Treating Fields (TTFields), an innovative therapy complementing chemotherapy for GBM treatment, which can significantly enhance overall survival, disease progression-free survival, and patient's quality of life. However, there is a dearth of health economics evaluation on TTFields therapy both domestically and internationally.

OBJECTIVE

The study aims to assess the cost-effectiveness of TTFields + temozolomide (TMZ) in comparison to TMZ alone for newly diagnosed GBM patients. The intent is to provide robust economic evidence to serve as a foundation for policymaking and decision-making processes in GBM treatment.

METHODS

We estimated outcomes for newly diagnosed GBM patients over a lifetime horizon using a partitioned survival model with three states: Progression-Free Survival, Progression Disease, and Death. The survival model was derived from a real-world study in China, with long-term survival data drawn from GBM epidemiology literature. Adverse event rates were sourced from the EF-14 trial data. Cost data, validated by expert consultation, was obtained from public literature and databases. Utility values were extracted from published literature. Using Microsoft Excel, we calculated expected costs and quality-adjusted life years (QALYs) over 15 years from a health system perspective. The willingness-to-pay threshold was set at three times the Chinese per capita Gross Domestic Product (GDP) in 2022, amounting to CN¥242,928 (US$37,655) /QALY. A 5% discount rate was applied to costs and utilities. Results underwent analysis through single factor and probability sensitivity analyses.

RESULTS

TTFields + TMZ demonstrated a mean increase in cost by CN¥389,326 (US$57,859) and an increase of 2.46 QALYs compared to TMZ alone. The incremental cost-effectiveness ratio (ICER) was CN¥157,979 (US$23,474) per QALY gained. The model exhibited heightened sensitivity to changes in the discount rate. Probability sensitivity analysis indicates that, under the existing threshold, the probability of TTFields + TMZ being economical is 95.60%.

CONCLUSIONS

This cost-effectiveness analysis affirms that incorporating TTFields into TMZ treatment proves to be cost-effective, given a threshold three times the Chinese per capita GDP.

Cost-effectiveness of treating advanced melanoma with tumor-infiltrating lymphocytes based on an international randomized phase 3 clinical trial

INTRODUCTION

In a multicenter, open-label randomized phase 3 clinical trial conducted in the Netherlands and Denmark, treatment with ex vivo-expanded tumor-infiltrating lymphocytes (TIL-NKI/CCIT) from autologous melanoma tumor compared with ipilimumab improved progression-free survival in patients with unresectable stage IIIC-IV melanoma after failure of first-line or second-line treatment. Based on this trial, we conducted a cost-utility analysis.

METHODS

A Markov decision model was constructed to estimate expected costs (expressed in 2021€) and outcomes (quality-adjusted life years (QALYs)) of TIL-NKI/CCIT versus ipilimumab in the Netherlands. The Danish setting was assessed in a scenario analysis. A modified societal perspective was applied over a lifetime horizon. TIL-NKI/CCIT production costs were estimated via activity-based costing. Through sensitivity analyses, uncertainties and their impact on the incremental cost-effectiveness ratio (ICER) were assessed.

RESULTS

Mean total undiscounted lifetime benefits were 4.47 life years (LYs) and 3.52 QALYs for TIL-NKI/CCIT and 3.33 LYs and 2.46 QALYs for ipilimumab. Total lifetime undiscounted costs in the Netherlands were €347,168 for TIL-NKI/CCIT (including €67,547 for production costs) compared with €433,634 for ipilimumab. Undiscounted lifetime cost in the Danish scenario were €337,309 and €436,135, respectively. This resulted in a dominant situation for TIL-NKI/CCIT compared with ipilimumab in both countries, meaning incremental QALYs were gained at lower costs. Survival probabilities, and utility in progressive disease affected the ICER most.

CONCLUSION

Based on the data of a randomized phase 3 trial, treatment with TIL-NKI/CCIT in patients with unresectable stage IIIC-IV melanoma is cost-effective and cost-saving, both in the current Dutch and Danish setting. These findings led to inclusion of TIL-NKI/CCIT as insured care and treatment guidelines. Publicly funded development of the TIL-NKI/CCIT cell therapy shows realistic promise to further explore development of effective personalized treatment while warranting economic sustainability of healthcare systems.

Combination tumor-treating fields treatment for patients with metastatic non-small cell lung cancer: A cost-effectiveness analysis

BACKGROUND

Tumor-treating field (TTFields) was a novel antitumor therapy that provided significant survival for previously treated metastatic non-small cell lung cancer (mNSCLC). The consistency of the cost of the new treatment regimen with its efficacy was the main objective of the study.

METHODS

The primary parameters, derived from the Phase 3 LUNAR study, were collected to evaluate the cost and efficacy of TTFields plus standard-of-care (SOC) (immune checkpoint inhibitors [ICIs] and docetaxel [DTX]) or SOC in patients with mNSCLC by establishing a three-state Markov model over a 15-year time horizon. Primary outcome measures for this study included costs, life-years (LYs), quality-adjusted LYs (QALYs), and incremental cost-effectiveness ratios (ICERs). Sensitivity analyses were performed.

RESULTS

The total costs of TTFields plus SOC, TTFields plus ICI, and TTFields plus DTX were $319,358, $338,688, and $298,477, generating 1.23 QALYs, 1.58 QALYs, and 0.89 QALYs, respectively. The ICERs of TTFields plus SOC versus SOC, TTFields plus ICI versus ICI, and TTFields plus DTX versus DTX were $613,379/QALY, $387,542/QALY, and $1,359,559/QALY, respectively. At willingness-to-pay (WTP) thresholds of $150,000/QALY, the probability of combination TTFields being cost-effective was 0%. In addition, TTFields plus SOC exhibited similar efficacy (1.12 QALYs and 1.14 QALYs) and costs ($309,822 and $312,531) in the treatment of squamous cell carcinoma (SCC) and non-squamous cell carcinoma (NSCC) populations.

CONCLUSIONS

In the United States, TTFields plus SOC as second-line treatment was not a more cost-effective strategy for patients with mNSCLC. Of the analyzed regimens, TTFields plus ICI was associated with most significant health benefits.

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.

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.

Epigenomic perturbation of novel EGFR enhancers reduces the proliferative and invasive capacity of glioblastoma and increases sensitivity to temozolomide

BACKGROUND

Glioblastoma (GB) is the most aggressive of all primary brain tumours and due to its highly invasive nature, surgical resection is nearly impossible. Patients typically rely on radiotherapy with concurrent temozolomide (TMZ) treatment and face a median survival of ~ 14 months. Alterations in the Epidermal Growth Factor Receptor gene (EGFR) are common in GB tumours, but therapies targeting EGFR have not shown significant clinical efficacy.

METHODS

Here, we investigated the influence of the EGFR regulatory genome on GB cells and identified novel EGFR enhancers located near the GB-associated SNP rs723527. We used CRISPR/Cas9-based approaches to target the EGFR enhancer regions, generating multiple modified GB cell lines, which enabled us to study the functional response to enhancer perturbation.

RESULTS

Epigenomic perturbation of the EGFR regulatory region decreases EGFR expression and reduces the proliferative and invasive capacity of glioblastoma cells, which also undergo a metabolic reprogramming in favour of mitochondrial respiration and present increased apoptosis. Moreover, EGFR enhancer-perturbation increases the sensitivity of GB cells to TMZ, the first-choice chemotherapeutic agent to treat glioblastoma.

CONCLUSIONS

Our findings demonstrate how epigenomic perturbation of EGFR enhancers can ameliorate the aggressiveness of glioblastoma cells and enhance the efficacy of TMZ treatment. This study demonstrates how CRISPR/Cas9-based perturbation of enhancers can be used to modulate the expression of key cancer genes, which can help improve the effectiveness of existing cancer treatments and potentially the prognosis of difficult-to-treat cancers such as glioblastoma.

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.

Medical Device Advances in the Treatment of Glioblastoma

Despite decades of research and the growing emergence of new treatment modalities, Glioblastoma (GBM) frustratingly remains an incurable brain cancer with largely stagnant 5-year survival outcomes of around 5%. Historically, a significant challenge has been the effective delivery of anti-cancer treatment. This review aims to summarize key innovations in the field of medical devices, developed either to improve the delivery of existing treatments, for example that of chemo-radiotherapy, or provide novel treatments using devices, such as sonodynamic therapy, thermotherapy and electric field therapy. It will highlight current as well as emerging device technologies, non-invasive versus invasive approaches, and by doing so provide a detailed summary of evidence from clinical studies and trials undertaken to date. Potential limitations and current challenges are discussed whilst also highlighting the exciting potential of this developing field. It is hoped that this review will serve as a useful primer for clinicians, scientists, and engineers in the field, united by a shared goal to translate medical device innovations to help improve treatment outcomes for patients with this devastating disease.

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.

Cost-Effectiveness of Short-Course Radiation Plus Temozolomide for the Treatment of Newly Diagnosed Glioblastoma Among Elderly Patients in China and the United States

Background: Glioblastoma multiforme (GBM) is a fatal type of brain tumor with a high incidence among elderly people. Temozolomide (TMZ) has proven to be an effective chemotherapeutic agent with significant survival benefits. This study aimed to evaluate the economic outcomes of radiotherapy (RT) and TMZ for the treatment of newly diagnosed GBM in elderly people in the United States (US) and China.

Methods: A partitioned survival model was constructed for RT plus TMZ and RT alone among patients with methylated and unmethylated tumor status. Base case calculations and one-way and probabilistic sensitivity analyses were performed. Life-years, quality-adjusted life-years (QALYs), costs (in 2021 US dollars [$] and Chinese Yuan Renminbi [¥]), and incremental cost-effectiveness ratios (ICERs) were calculated.

Results: RT plus TMZ was found to be associated with significantly higher costs and QALYs in all groups. Only US patients with methylated status receiving RT plus TMZ had an ICER ($89358.51) less than the willingness-to-pay (WTP) threshold of $100000 per QALY gained when compared with receiving RT alone. When the WTP threshold ranged from $100000 to $150000 from the US perspective, the probability of RT plus TMZ being cost-effective increased from 80.5 to 99.8%. The cost of TMZ must be lower than ¥120 per 20 mg for RT plus TMZ to be cost-effective among patients with methylated tumor status in China.

Conclusion: RT plus TMZ was not cost-effective in China, and a reduction in the TMZ price was justified. However, it is highly likely to be cost-effective for patients with methylated tumor status in the US.

Tumor-Treating Fields for the treatment of glioblastoma: a systematic review and meta-analysis

BACKGROUND

Tumor-Treating Fields (TTFields) is an emerging treatment modality for glioblastoma (GBM). Studies have shown a good safety profile alongside improved efficacy in newly diagnosed GBM (ndGBM), while a less clear effect was shown for recurrent GBM (rGBM). Despite regulatory support, sectors of the neuro-oncology community have been reluctant to accept it as part of the standard treatment protocol. To establish an objective understanding of TTFields' mechanism of action, safety, efficacy, and economical implications, we conducted a systematic literature review and meta-analysis.

METHODS

A systematic search was conducted in PubMed, Scopus, and Cochrane databases. Twenty studies met the pre-defined inclusion criteria, incorporating 1636 patients (542 ndGBM and 1094 rGBM), and 11 558 patients (6403 ndGBM and 5155 rGBM) analyzed for the clinical outcomes and safety endpoints, respectively.

RESULTS

This study demonstrated improved clinical efficacy and a good safety profile of TTFields. For ndGBM, pooled median overall survival (OS) and progression-free survival (PFS) were 21.7 (95%CI = 19.6-23.8) and 7.2 (95%CI = 6.1-8.2) months, respectively. For rGBM, pooled median OS and PFS were 10.3 (95%CI = 8.3-12.8) and 5.7 (95%CI = 2.8-10) months, respectively. Compliance of ≥75% was associated with an improved OS and the predominant adverse events were dermatologic, with a pooled prevalence of 38.4% (95%CI = 32.3-44.9). Preclinical studies demonstrated TTFields' diverse molecular mechanism of action, its potential synergistic efficacy, and suggest possible benefits for certain populations.

CONCLUSIONS

This study supports the use of TTFields for GBM, alongside the standard-of-care treatment protocol, and provides a practical summary, discussing the current clinical and preclinical aspects of the treatment and their implication on the disease course.

Challenges and Perspectives of Standard Therapy and Drug Development in High-Grade Gliomas

Despite their low incidence rate globally, high-grade gliomas (HGG) remain a fatal primary brain tumor. The recommended therapy often is incapable of resecting the tumor entirely and exclusively targeting the tumor leads to tumor recurrence and dismal prognosis. Additionally, many HGG patients are not well suited for standard therapy and instead, subjected to a palliative approach. HGG tumors are highly infiltrative and the complex tumor microenvironment as well as high tumor heterogeneity often poses the main challenges towards the standard treatment. Therefore, a one-fit-approach may not be suitable for HGG management. Thus, a multimodal approach of standard therapy with immunotherapy, nanomedicine, repurposing of older drugs, use of phytochemicals, and precision medicine may be more advantageous than a single treatment model. This multimodal approach considers the environmental and genetic factors which could affect the patient's response to therapy, thus improving their outcome. This review discusses the current views and advances in potential HGG therapeutic approaches and, aims to bridge the existing knowledge gap that will assist in overcoming challenges in HGG.

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

Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults and continues to portend poor survival, despite multimodal treatment using surgery and chemoradiotherapy. The addition of tumour-treating fields (TTFields)-an approach in which alternating electrical fields exert biophysical force on charged and polarisable molecules known as dipoles-to standard therapy, has been shown to extend survival for patients with newly diagnosed GBM, recurrent GBM and mesothelioma, leading to the clinical approval of this approach by the FDA. TTFields represent a non-invasive anticancer modality consisting of low-intensity (1-3 V/cm), intermediate-frequency (100-300 kHz), alternating electric fields delivered via cutaneous transducer arrays configured to provide optimal tumour-site coverage. Although TTFields were initially demonstrated to inhibit cancer cell proliferation by interfering with mitotic apparatus, it is becoming increasingly clear that TTFields show a broad mechanism of action by disrupting a multitude of biological processes, including DNA repair, cell permeability and immunological responses, to elicit therapeutic effects. This review describes advances in our current understanding of the mechanisms by which TTFields mediate anticancer effects. Additionally, we summarise the landscape of TTFields clinical trials across various cancers and consider how emerging preclinical data might inform future clinical applications for TTFields.

Tumor Treating Fields in the Management of Patients with Malignant Gliomas

OPINION STATEMENT

Malignant gliomas remain a challenging cancer to treat due to limitations in both therapeutic and efficacious options. Tumor treating fields (TTFields) have emerged as a novel, locoregional, antineoplastic treatment modality with favorable efficacy and safety being demonstrated in the most aggressive type of malignant gliomas, glioblastoma (GBM). In 2 large randomized, controlled phase 3 trials, the addition of TTFields was associated with increased overall survival when combined with adjuvant temozolomide (TMZ) chemotherapy in patients with newly diagnosed GBM (ndGBM) and comparable overall survival compared with standard chemotherapy in patients with recurrent GBM (rGBM). TTFields target cancer cells by several mechanisms of action (MoA) including suppression of proliferation, migration and invasion, disruption of DNA repair and angiogenesis, antimitotic effects, and induction of apoptosis and immunogenic cell death. Having several MoAs makes TTFields an attractive modality to combine with standard, salvage, and novel treatment regimens (e.g., radiotherapy, chemotherapy, and immunotherapy). Treatment within the field of malignant gliomas is evolving to emphasize combinatorial approaches that work synergistically to improve patient outcomes. Here, we review the current use of TTFields in GBM, discuss MOA and treatment delivery, and consider the potential for its wider adoption in other gliomas.

Tumor treating fields for glioblastoma: should it or will it ever be adopted?

PURPOSE OF REVIEW

The purpose of this review is to discuss how a new treatment modality, tumor treating fields, may be incorporated into the oncologic care for patients with glioblastoma.

RECENT FINDINGS

Tumor treating fields are a new treatment modality available to patients with newly diagnosed and recurrent glioblastoma. Alternating electric fields are delivered via a wearable, removable device affixed to the scalp of patients with supratentorial glioblastoma. With continuous use, the application of tumor treating fields combined with temozolomide chemotherapy has been shown to improve overall survival compared with temozolomide alone in patients with newly diagnosed glioblastoma. Adverse events attributable to the device are limited to localized skin reactions. Despite compendium guidelines in support of its use and Food and Drug Administration (FDA) approval, tumor treating fields have been slow to be adopted in the neuro-oncology community. Critics have raised concerns about the generalizability of the study data, patient quality of life, and mechanism of action of this therapy.

SUMMARY

Tumor treating fields are available for the treatment of both newly diagnosed and recurrent glioblastoma and represent a new category of treatment modalities in oncologic therapy. This novel device has received FDA approval but has been slow to be adopted into clinical practice.

Current usage of tumor treating fields for glioblastoma

Background

Tumor Treating Fields (TTF) have entered clinical practice for newly diagnosed and recurrent glioblastoma (GGM). However, controversies remain unresolved with regard to appropriate usage. We sought to determine TTF usage in major academic neuro-oncology programs in New York City, USA and Heidelberg, Germany and understand current attitudes toward TTF usage among providers.

Methods

We retrospectively determined TTF usage among patients with GGM, before and since the publication of key clinical trial results and regulatory approvals. We also surveyed attendees of an educational session related to TTF during the 2019 American Society of Clinical Oncology annual meeting.

Results

TTF usage remains infrequent (3-12% of patients with newly diagnosed GBM, and 0-16% of patients with recurrent disease) in our practices, although it has increased over time. Among 30 survey respondents (77% of whom self-identified as neuro- or medical oncologists), 60% were convinced that TTF prolongs survival for newly diagnosed GGM despite published phase III data and regulatory approval, and only 30% viewed TTF as definitively part of the standard of care treatment. A majority (87%) opposed mandating TTF incorporation into the design of clinical trials.

Conclusions

Providers continue to view TTF with some level of skepticism, with a lack of additional supportive data and logistical concerns representing continued barriers to uptake.

The Value of Tumor Treating Fields in Glioblastoma

Glioblastoma (GBM) is one of the most common tumors of the central nervous system, which is the most lethal brain cancer. GBM treatment is based primarily on surgical resection, combined with radiotherapy and chemotherapy. Despite the positive treatment, progression free survival and overall survival were not significantly prolonged because GBM almost always recurs. We are always looking forward to some new and effective treatments. In recent years, a novel treatment method called tumor treating fields (TTFields) for cancer treatment has been proposed. TTFields devices were approved by the Food and Drug Administration (FDA) for adjuvant treatment of recurrent and newly diagnosed GBMs in 2011 and 2015, respectively. This became the first breakthrough treatment for GBM in the past 10 years after the FDA approved bevacizumab for patients with relapsed GBM in 2009. This paper summarized the research results of TTFields in recent years and elaborated the mechanism of action of TTFields on GBM, including cell and animal experimental research, clinical application and social benefits.

Treatment of newly diagnosed glioblastoma in the elderly: a network meta-analysis

BACKGROUND

A glioblastoma is a fatal type of brain tumour for which the standard of care is maximum surgical resection followed by chemoradiotherapy, when possible. Age is an important consideration in this disease, as older age is associated with shorter survival and a higher risk of treatment-related toxicity.

OBJECTIVES

To determine the most effective and best-tolerated approaches for the treatment of elderly people with newly diagnosed glioblastoma. To summarise current evidence for the incremental resource use, utilities, costs and cost-effectiveness associated with these approaches.

SEARCH METHODS

We searched electronic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase to 3 April 2019, and the NHS Economic Evaluation Database (EED) up to database closure. We handsearched clinical trial registries and selected neuro-oncology society conference proceedings from the past five years.

SELECTION CRITERIA

Randomised trials (RCTs) of treatments for glioblastoma in elderly people. We defined 'elderly' as 70+ years but included studies defining 'elderly' as over 65+ years if so reported.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods for study selection and data extraction. Where sufficient data were available, treatment options were compared in a network meta-analysis (NMA) using Stata software (version 15.1). For outcomes with insufficient data for NMA, pairwise meta-analysis were conducted in RevMan. The GRADE approach was used to grade the evidence.

MAIN RESULTS

We included 12 RCTs involving approximately 1818 participants. Six were conducted exclusively among elderly people (either defined as 65 years or older or 70 years or older) with newly diagnosed glioblastoma, the other six reported data for an elderly subgroup among a broader age range of participants. Most participants were capable of self-care. Study quality was commonly undermined by lack of outcome assessor blinding and attrition. NMA was only possible for overall survival; other analyses were pair-wise meta-analyses or narrative syntheses. Seven trials contributed to the NMA for overall survival, with interventions including supportive care only (one trial arm); hypofractionated radiotherapy (RT40; four trial arms); standard radiotherapy (RT60; five trial arms); temozolomide (TMZ; three trial arms); chemoradiotherapy (CRT; three trial arms); bevacizumab with chemoradiotherapy (BEV_CRT; one trial arm); and bevacizumab with radiotherapy (BEV_RT). Compared with supportive care only, NMA evidence suggested that all treatments apart from BEV_RT prolonged survival to some extent. Overall survival High-certainty evidence shows that CRT prolongs overall survival (OS) compared with RT40 (hazard ratio (HR) 0.67, 95% confidence interval (CI) 0.56 to 0.80) and low-certainty evidence suggests that CRT may prolong overall survival compared with TMZ (TMZ versus CRT: HR 1.42, 95% CI 1.01 to 1.98). Low-certainty evidence also suggests that adding BEV to CRT may make little or no difference (BEV_CRT versus CRT: HR 0.83, 95% CrI 0.48 to 1.44). We could not compare the survival effects of CRT with different radiotherapy fractionation schedules (60 Gy/30 fractions and 40 Gy/15 fractions) due to a lack of data. When treatments were ranked according to their effects on OS, CRT ranked higher than TMZ, RT and supportive care only, with the latter ranked last. BEV plus RT was the only treatment for which there was no clear benefit in OS over supportive care only.   One trial comparing tumour treating fields (TTF) plus adjuvant chemotherapy (TTF_AC) with adjuvant chemotherapy alone could not be included in the NMA as participants were randomised after receiving concomitant chemoradiotherapy, not before. Findings from the trial suggest that the intervention probably improves overall survival in this selected patient population. We were unable to perform NMA for other outcomes due to insufficient data. Pairwise analyses were conducted for the following. Quality of life Moderate-certainty narrative evidence suggests that overall, there may be little difference in QoL between TMZ and RT, except for discomfort from communication deficits, which are probably more common with RT (1 study, 306 participants, P = 0.002). Data on QoL for other comparisons were sparse, partly due to high dropout rates, and the certainty of the evidence tended to be low or very low. Progression-free survival High-certainty evidence shows that CRT increases time to disease progression compared with RT40 (HR 0.50, 95% CI 0.41 to 0.61); moderate-certainty evidence suggests that RT60 probably increases time to disease progression compared with supportive care only (HR 0.28, 95% CI 0.17 to 0.46), and that BEV_RT probably increases time to disease progression compared with RT40 alone (HR 0.46, 95% CI 0.27 to 0.78). Evidence for other treatment comparisons was of low- or very low-certainty. Severe adverse events Moderate-certainty evidence suggests that TMZ probably increases the risk of grade 3+ thromboembolic events compared with RT60 (risk ratio (RR) 2.74, 95% CI 1.26 to 5.94; participants = 373; studies = 1) and also the risk of grade 3+ neutropenia, lymphopenia, and thrombocytopenia. Moderate-certainty evidence also suggests that CRT probably increases the risk of grade 3+ neutropenia, leucopenia and thrombocytopenia compared with hypofractionated RT alone. Adding BEV to CRT probably increases the risk of thromboembolism (RR 16.63, 95% CI 1.00 to 275.42; moderate-certainty evidence). Economic evidence There is a paucity of economic evidence regarding the management of newly diagnosed glioblastoma in the elderly. Only one economic evaluation on two short course radiotherapy regimen (25 Gy versus 40 Gy) was identified and its findings were considered unreliable.

AUTHORS' CONCLUSIONS

For elderly people with glioblastoma who are self-caring, evidence suggests that CRT prolongs survival compared with RT and may prolong overall survival compared with TMZ alone. For those undergoing RT or TMZ therapy, there is probably little difference in QoL overall. Systemic anti-cancer treatments TMZ and BEV carry a higher risk of severe haematological and thromboembolic events and CRT is probably associated with a higher risk of these events. Current evidence provides little justification for using BEV in elderly patients outside a clinical trial setting. Whilst the novel TTF device appears promising, evidence on QoL and tolerability is needed in an elderly population. QoL and economic assessments of CRT versus TMZ and RT are needed. More high-quality economic evaluations are needed, in which a broader scope of costs (both direct and indirect) and outcomes should be included.

Quality-adjusted life years in glioma patients: a systematic review on currently available data and the lack of evidence-based utilities

BACKGROUND

Cost-effectiveness studies gain importance in the context of rising health care expenses and treatment options. Especially in the neuro-oncological context, surgical therapy may increase overall survival, but restrain the patient by postoperative disability. Quality-adjusted life years, express treatment effects and are based on health utilities. In our study, we analyze the current evidence on health economic evaluations in glioma patients.

MATERIAL AND METHODS

We performed a systematic database search including Medline and Cochrane Library. Studies were critically appraised for statistical analyzes including glioma patients, health economic modeling and detailed health outcome. Study evidence was classified according to levels of evidence for therapeutic studies from the Centre for Evidence-Based Medicine (Oxford).

RESULTS

37 studies (1995-2018) were identified, 29 matched our inclusion criteria. Studies addressed surgical cost-efficiency and/or the standard treatment, postoperative chemotherapy (n = 6) and 5-ALA (n = 3). Only 16 studies used QALY as the outcome measure, most used overall survival or life years gained (LYG). Utilities were either based on one single study (Garside et al. in Health Technol Assess 11:iii-iv, ix-221) or derived from visual analogue scale (VAS). None assessed quality of life values for specific health statuses or utilities. Incremental cost-effectiveness ratios varied from 8325€ per QALY (5-ALA) to 518,342€ per LYG (tumor treating fields).

CONCLUSIONS

Only one study generated utility values to conduct cost-effectiveness analysis (CEA); most studies used indirect outcomes such as LYG or based their model on previously published data. Health economic evaluations lack specific utilities, further investigations are necessary to conduct reliable CEA in the neurosurgical context.

Cost-effectiveness of tumor-treating fields added to maintenance temozolomide in patients with glioblastoma: an updated evaluation using a partitioned survival model

PURPOSE

A first cost-effectiveness analysis has raised a strong concern regarding the cost of tumor treatment fields (TTF) added to maintenance temozolomide for patients with glioblastoma. This evaluation was based on effectiveness outcomes from an interim analysis of the pivotal trial, moreover it used a "standard" Markov model. Our objective was to update the cost-effectiveness evaluation using the more flexible potential of the "partitioned survival" model design and using the latest effectiveness data.

METHODS

We developed the model with three mutually exclusive health states: stable disease, progressive disease, and dead. Good fit parametric models were developed for overall survival and progression free survival and these generated clinically plausible extrapolations beyond the observed data. We adopted the perspective of the French national health insurance and used a 20-year time horizon. Results were expressed as cost/life-years (LY) gained (LYG).

RESULTS

The base case model generated incremental benefit of 0.604 LY at a cost of €453,848 which, after 4% annual discounting of benefits and costs, yielded an incremental cost effectiveness ratio (ICER) of €510,273/LYG. Using sensitivity analyses and bootstrapping methods results were found to be relatively robust and were only sensitive to TTF device costs and the modelling of overall survival. To achieve an ICER below €100,000/LYG would require a reduction in TTF device cost of approximately 85%.

CONCLUSIONS

Using a different type of model and updated survival outcomes, our results show TTF remains an intervention that is not cost-effective, which greatly restrains its diffusion to potentially eligible patients.