A Phase I clinical trial of dose-escalated metabolic therapy combined with concomitant radiation therapy in high-grade glioma

Inhibition of 6-phosphogluconate dehydrogenase suppresses esophageal squamous cell carcinoma growth and enhances the anti-tumor effects of metformin via the AMPK/mTOR pathway

Metabolic reprogramming plays a pivotal role in the development and progression of tumors. Tumor cells rely on glycolysis as their primary energy production pathway and effectively utilize biomolecules generated by the pentose phosphate pathway (PPP) for efficient biosynthesis. However, the role of 6-phosphogluconate dehydrogenase (6PGD), a crucial enzyme in the PPP, remains unexplored in esophageal squamous cell carcinoma (ESCC). In this study, we observed a significant upregulation of 6PGD expression in ESCC tissues, which correlated with an unfavorable prognosis among patients. The experiments demonstrated that knockdown of 6PGD induces oxidative stress and suppresses ESCC cell proliferation. Mechanistically, this is achieved through AMPK activation and subsequent inhibition of downstream mTOR phosphorylation. Moreover, physcion has been found to inhibit 6PGD activity and exert its anti-ESCC effect via the AMPK/mTOR pathway. Subsequently, we conducted both in vitro and in vivo experiments to validate the anticancer efficacy of combining metformin, an AMPK activator, with physcion. The results demonstrated a significantly enhanced inhibition of ESCC growth. This study elucidates the impact of 6PGD on ESCC cell proliferation along with its underlying molecular mechanisms, highlighting its potential as a therapeutic target for ESCC. Furthermore, we investigated a novel approach for improved anti-tumor therapy involving physcion and metformin. These findings will contribute new insights to clinical treatment strategies for ESCC while providing a theoretical foundation for developing molecular targeted therapies.

Metformin and glioma: Targeting metabolic dysregulation for enhanced therapeutic outcomes

Glioma, a highly aggressive form of brain cancer, continues to pose significant therapeutic challenges in the field of medicine. Its invasive nature and resistance to traditional treatments make it particularly difficult to combat. This review examines the potential of metformin, a commonly prescribed antidiabetic medication, as a promising new treatment option for glioma. The potential of metformin to target crucial metabolic pathways in cancer cells presents an encouraging approach to improve therapeutic outcomes. The review explores the complexities of metabolic reprogramming in glioma and metformin's role in inhibiting these metabolic pathways. Preclinical studies demonstrate metformin's efficacy in reducing tumor growth and enhancing the sensitivity of glioma cells to chemotherapy and radiotherapy. Furthermore, clinical studies highlight metformin's potential in improving progression-free survival and overall survival rates in glioma patients. The review also addresses the synergistic effects of combining metformin with other therapeutic agents, such as temozolomide and radiotherapy, to overcome drug resistance and improve treatment efficacy. Despite the promising findings, the review acknowledges the need for further clinical trials to establish optimal dosing regimens, understand the molecular mechanisms underlying metformin's antitumor effects, and identify patient populations that would benefit the most from metformin-based therapies. Additionally, the potential side effects and the long-term impact of metformin on Glioma patients require careful evaluation. In conclusion, this review underscores the potential of metformin as a repurposed drug in glioma treatment, emphasizing its multifaceted role in targeting metabolic dysregulation. Metformin holds promise as part of a combination therapy approach to improve the therapeutic landscape of glioma and offers hope for better patient outcomes.

Function of AMPK/mTOR Signaling in TGF-β1-Induced Pterygium Fibroblast Proliferation and Transdifferentiation

PURPOSE

This study aimed to investigate the regulatory role of the AMP-activated protein kinase (AMPK)/mechanistic target of rapamycin (mTOR) signaling pathway in mediating transforming growth factor-beta 1 (TGF-β1)-induced cellular proliferation and transdifferentiation processes in human pterygium fibroblasts (HPFs).

METHODS

HPFs were stimulated with TGF-β1 in vitro. Cell viability was assessed using the CCK-8 assay at 12/24/48-h post-stimulation, while migratory capacity was evaluated through standardized wound healing assays. Quantitative real-time PCR (qPCR) and western blotting analyses were employed to evaluate the expression of proliferation marker proliferating cell nuclear antigen (PCNA) and myofibroblast transdifferentiation biomarker α-smooth muscle actin (α-SMA). Western blotting further characterized the activation status of AMPK/mTOR signaling by quantifying phosphorylated AMPK (p-AMPK) and phosphorylated mTOR (p-mTOR), with total AMPK and mTOR levels serving as loading controls. To establish mechanistic causality, TGF-β1-primed HPFs were modulated using the AMPK inhibitor Compound C and activator AICAR for 24 h. Functional consequences were analyzed through CCK-8 viability assays and wound healing assays, while molecular correlates were assessed via qPCR and western blotting for PCNA, α-SMA, and pathway components. This comprehensive approach delineated the AMPK/mTOR axis as a critical regulator of TGF-β1-driven fibrotic phenotype acquisition in HPFs.

RESULTS

Following TGF-β1 pretreatment-induced activation of human HPFs, both cell viability and migratory capacity were markedly enhanced, with concomitant upregulation of PCNA and α-SMA. Compound C-mediated AMPK inhibition potentiated the TGF-β1-induced enhancements in HPFs viability and migration rate, concomitant with reduced p-AMPK/AMPK ratio and elevated expression of PCNA, α-SMA, and p-mTOR/mTOR ratio. Conversely, AICAR-driven AMPK activation attenuated TGF-β1-stimulated effects, demonstrating diminished viability, suppressed migratory capacity, increased p-AMPK/AMPK ratio, and decreased expression of PCNA, α-SMA, and p-mTOR/mTOR ratio.

CONCLUSIONS

This study demonstrates the critical regulatory role of the AMPK/mTOR signaling pathway in controlling TGF-β1-induced proliferation and transdifferentiation in HPFs, thereby providing a potential mechanistic framework for developing novel therapeutic interventions targeting fibrotic ocular surface disorders.

Comprehensive Overview of Ketone Bodies in Cancer Metabolism: Mechanisms and Application

Reprogramming energy metabolism is pivotal to tumor development. Ketone bodies (KBs), which are generated during lipid metabolism, are fundamental bioactive molecules that can be modulated to satisfy the escalating metabolic needs of cancer cells. At present, a burgeoning body of research is concentrating on the metabolism of KBs within tumors, investigating their roles as signaling mediators, drivers of post-translational modifications, and regulators of inflammation and oxidative stress. The ketogenic diet (KD) may enhance the sensitivity of various cancers to standard therapies, such as chemotherapy and radiotherapy, by exploiting the reprogrammed metabolism of cancer cells and shifting the metabolic state from glucose reliance to KB utilization, rendering it a promising candidate for adjunct cancer therapy. Nonetheless, numerous questions remain regarding the expression of key metabolic genes across different tumors, the regulation of their activities, and the impact of individual KBs on various tumor types. Further investigation is imperative to resolve the conflicting data concerning KB synthesis and functionality within tumors. This review aims to encapsulate the intricate roles of KBs in cancer metabolism, elucidating a comprehensive grasp of their mechanisms and highlighting emerging clinical applications, thereby setting the stage for future investigations into their therapeutic potential.

Towards Effective Treatment of Glioblastoma: The Role of Combination Therapies and the Potential of Phytotherapy and Micotherapy

Glioblastoma multiforme (GBM) is one of the most aggressive and difficult-to-treat brain tumors, with a poor prognosis due to its high resistance to conventional therapies. Current treatment options, including surgical resection, radiotherapy, and chemotherapy, have limited effectiveness in improving long-term survival. Despite the emergence of new therapies, monotherapy approaches have not shown significant improvements, highlighting the need for innovative therapeutic strategies. Combination therapies appear to be the most promising solution, as they target multiple molecular pathways involved in GBM progression. One area of growing interest is the incorporation of phytotherapy and micotherapy as complementary treatments, which offer potential benefits due to their anti-tumor, anti-inflammatory, and immunomodulatory properties. This review examines the current challenges in GBM treatment, discusses the potential of combination therapies, and highlights the promising role of phytotherapy and micotherapy as integrative therapeutic options for GBM management.

Clinical research framework proposal for ketogenic metabolic therapy in glioblastoma

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, with a universally lethal prognosis despite maximal standard therapies. Here, we present a consensus treatment protocol based on the metabolic requirements of GBM cells for the two major fermentable fuels: glucose and glutamine. Glucose is a source of carbon and ATP synthesis for tumor growth through glycolysis, while glutamine provides nitrogen, carbon, and ATP synthesis through glutaminolysis. As no tumor can grow without anabolic substrates or energy, the simultaneous targeting of glycolysis and glutaminolysis is expected to reduce the proliferation of most if not all GBM cells. Ketogenic metabolic therapy (KMT) leverages diet-drug combinations that inhibit glycolysis, glutaminolysis, and growth signaling while shifting energy metabolism to therapeutic ketosis. The glucose-ketone index (GKI) is a standardized biomarker for assessing biological compliance, ideally via real-time monitoring. KMT aims to increase substrate competition and normalize the tumor microenvironment through GKI-adjusted ketogenic diets, calorie restriction, and fasting, while also targeting glycolytic and glutaminolytic flux using specific metabolic inhibitors. Non-fermentable fuels, such as ketone bodies, fatty acids, or lactate, are comparatively less efficient in supporting the long-term bioenergetic and biosynthetic demands of cancer cell proliferation. The proposed strategy may be implemented as a synergistic metabolic priming baseline in GBM as well as other tumors driven by glycolysis and glutaminolysis, regardless of their residual mitochondrial function. Suggested best practices are provided to guide future KMT research in metabolic oncology, offering a shared, evidence-driven framework for observational and interventional studies.

Targeting Mitochondria in Glioma: New Hopes for a Cure

Drugs targeting mitochondrial energy metabolism are emerging as promising antitumor therapeutics. Glioma treatment is extremely challenging due to the high complexity of the tumor and the high cellular heterogeneity. From a metabolic perspective, glioma cancer cells can be classified into the oxidative metabolic phenotype (mainly depending on mitochondrial respiration for energy production) and glycolytic phenotype or "Warburg effect" (mainly depending on glycolysis). Herein, we reviewed the function of novel bio-active molecules targeting oxidative phosphorylation (OXPHOS), mitochondrial membrane potential and mitochondrial dynamics. These molecules exhibit intriguing preclinical and clinical results and have been proven to be promising candidates to be further developed for glioma therapy. However, despite these initial encouraging results, it is imperative to rigorously assess the side effects of these metabolic drugs, which have a non-negligible toxicity profile.

Systematic Review and Clinical Insights: The Role of the Ketogenic Diet in Managing Glioblastoma in Cancer Neuroscience

Recent scientific research has shown that the ketogenic diet may have potential benefits in a variety of medical fields, which has led to the diet receiving a substantial amount of attention. Clinical and experimental research on brain tumors has shown that the ketogenic diet has a satisfactory safety profile. This safety profile has been established in a variety of applications, including the management of obesity and the treatment of drug-resistant epileptic cases. However, in human studies, the impact of ketogenic therapy on the growth of tumors and the life expectancy of patients has not provided results that are well characterized. Consequently, our purpose is to improve the comprehension of these features by succinctly presenting the developments and conclusions that have been gained from the most recent study that pertains to this non-pharmacological technique. According to the findings of our study, patients with brain tumors who stick to a ketogenic diet are more likely to experience improved survival rates. However, it is required to conduct additional research on humans in order to more accurately define the anti-tumor efficiency of this diet as well as the underlying processes that support the therapeutic effects of this dieting regimen.

Dietary Influence on Drug Efficacy: A Comprehensive Review of Ketogenic Diet-Pharmacotherapy Interactions

It is widely acknowledged that the ketogenic diet (KD) has positive physiological effects as well as therapeutic benefits, particularly in the treatment of chronic diseases. Maintaining nutritional ketosis is of utmost importance in the KD, as it provides numerous health advantages such as an enhanced lipid profile, heightened insulin sensitivity, decreased blood glucose levels, and the modulation of diverse neurotransmitters. Nevertheless, the integration of the KD with pharmacotherapeutic regimens necessitates careful consideration. Due to changes in their absorption, distribution, metabolism, or elimination, the KD can impact the pharmacokinetics of various medications, including anti-diabetic, anti-epileptic, and cardiovascular drugs. Furthermore, the KD, which is characterised by the intake of meals rich in fats, has the potential to impact the pharmacokinetics of specific medications with high lipophilicity, hence enhancing their absorption and bioavailability. However, the pharmacodynamic aspects of the KD, in conjunction with various pharmaceutical interventions, can provide either advantageous or detrimental synergistic outcomes. Therefore, it is important to consider the pharmacokinetic and pharmacodynamic interactions that may arise between the KD and various drugs. This assessment is essential not only for ensuring patients' compliance with treatment but also for optimising the overall therapeutic outcome, particularly by mitigating adverse reactions. This highlights the significance and necessity of tailoring pharmacological and dietetic therapies in order to enhance the effectiveness and safety of this comprehensive approach to managing chronic diseases.

Survival Impact of Combined Biguanide and Temozolomide in Glioblastoma Preclinical Models: A Systematic Review and Meta-Analysis

BACKGROUND

Glioblastoma (GBM) is an aggressive tumor known for its poor prognosis. Despite extensive research into its molecular and clinical aspects, the current management strategies have shown limited efficacy in improving survival rate. Despite some preclinical studies exploring the combination of temozolomide (TMZ) with biguanides such as metformin (MET) and others, the potential benefits of this combination remain uncertain. The aim of this study is to evaluate the overall survival (OS) in GBM murine-models treated with a combination of TMZ + biguanide compared to those treated with TMZ alone.

METHODS

We systematically searched Medline, Embase, and Lilacs databases for studies comparing TMZ + biguanide versus TMZ alone in GBM models and reporting OS data. The mean difference (MD) with 95% confidence interval and random-effects model was adopted.

RESULTS

Nine studies were included in this systematic review. The meta-analysis comprised 6 studies involving 85 rat-models, with 45 subjects undergoing combined-treatment. GBM-murine models treated with TMZ + biguanide exhibited notably superior OS rates compared to those who received TMZ alone, showing an MD of 21.0 days (6.9-35.0). Within the subgroup of orthotopic models, the OS was also significantly better in combination-therapy with an MD of 23.7 days (6.5-40.9). Similarly, in the subgroup where MET was used as biguanide therapy, TMZ + MET demonstrated a significant increase in OS, with an MD of 27.4 days (6.0-48.8). In immunocompromised models, the combination-therapy also exhibited higher survival rates, with an MD of 13 days (9.4-16.6).

CONCLUSIONS

This systematic review and meta-analysis provide compelling evidence regarding the beneficial effects of TMZ + biguanide in GBM models compared with TMZ alone, resulting in a significant improvement in OS.

Metformin shows anti-neoplastic properties by inhibition of oxidative phosphorylation and glycolysis in epidermolysis bullosa-associated aggressive cutaneous squamous cell carcinoma

BACKGROUND

While most cutaneous squamous cell carcinomas (cSCCs) are treatable, certain high-risk cSCCs, such as those in recessive dystrophic epidermolysis bullosa (RDEB) patients, are particularly aggressive. Owing to repeated wounding, inflammation and unproductive healing, RDEB patients have a 68% cumulative risk of developing life-threatening cSCCs by the age of 35, and a 70% risk of death by the age of 45. Despite aggressive treatment, cSCC represents the leading cause of premature mortality in these patients, highlighting an unmet clinical need. Increasing evidence points to a role of altered metabolism in the initiation and maintenance of cSCC, making metabolism a potential therapeutic target.

OBJECTIVES

We sought to determine the feasibility of targeting tumour cell energetics as a strategy to selectively hinder the growth advantage of aggressive cSCC.

METHODS

We evaluated the cell energetics profiles of RDEB-SCC cells by analysing available gene expression data against multiple gene signatures and single-gene targets linked to metabolic reprogramming. Additionally, we employed real-time metabolic profiling to measure glycolysis and respiration in these cells. Furthermore, we investigated the anti-neoplastic properties of the metformin against human and murine high-risk cSCCs in vitro and in vivo.

RESULTS

Gene expression analyses highlighted a divergence in cell energetics profiles between RDEB-SCC and non-malignant RDEB keratinocytes, with tumour cells demonstrating enhanced respiration and glycolysis scores. Real-time metabolic profiling supported these data and additionally highlighted a metabolic plasticity of RDEB-SCC cells. Against this background, metformin exerted an anti-neoplastic potential by hampering both respiration and glycolysis, and by inhibiting proliferation in vitro. Metformin treatment in an analogous model of fast-growing murine cSCC resulted in delayed tumour onset and slower tumour growth, translating to a 29% increase in median overall survival.

CONCLUSIONS

Our data indicate that metformin exerts anti-neoplastic properties in aggressive cSCCs that exhibit high-risk features by interfering with respiration and glycolytic processes.

Adherence to Healthy Dietary Patterns and Glioma: A Matched Case-Control Study

Recent studies have revealed a putative relationship between diet and glioma development and prognosis, but few studies have examined the association between overall diet and glioma risk. This study, conducted in China, employed a hospital-based case-control approach. The researchers utilized an a priori method based on dietary data to evaluate compliance scores for five healthy dietary patterns (the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, the Mediterranean-DASH diet Intervention for Neurodegenerative Delay (MIND) diet, the Paleolithic diet, and the Planetary Health Diet) in 1012 participants. At the same time, data-driven methods were used to explore the association between dietary patterns and glioma via principal component analysis (PCA). In the multivariate model, adhering to the Mediterranean diet (odds ratio (OR) = 0.29; 95% confidence interval (95% CI): 0.17-0.52), the DASH diet (OR = 0.09; 95% CI: 0.04-0.18), the MIND diet (OR = 0.25; 95% CI: 0.14-0.44), and the Paleolithic diet (OR = 0.13; 95% CI: 0.06-0.25) was associated with a reduced glioma risk. The results of PCA suggested that increasing the intake of plant-based foods and fish and limiting foods rich in carbohydrates, fats, and salts were associated with a reduced glioma risk. There was a substantial nonlinear dose-response association between glioma and the Mediterranean diet score. However, the DASH diet score, the MIND diet score, and the Paleolithic diet score exhibited linear dose-response relationships. Therefore, this study finds that dietary patterns may be an influencing factor for glioma risk.

From signalling pathways to targeted therapies: unravelling glioblastoma's secrets and harnessing two decades of progress

Glioblastoma, a rare, and highly lethal form of brain cancer, poses significant challenges in terms of therapeutic resistance, and poor survival rates for both adult and paediatric patients alike. Despite advancements in brain cancer research driven by a technological revolution, translating our understanding of glioblastoma pathogenesis into improved clinical outcomes remains a critical unmet need. This review emphasises the intricate role of receptor tyrosine kinase signalling pathways, epigenetic mechanisms, and metabolic functions in glioblastoma tumourigenesis and therapeutic resistance. We also discuss the extensive efforts over the past two decades that have explored targeted therapies against these pathways. Emerging therapeutic approaches, such as antibody-toxin conjugates or CAR T cell therapies, offer potential by specifically targeting proteins on the glioblastoma cell surface. Combination strategies incorporating protein-targeted therapy and immune-based therapies demonstrate great promise for future clinical research. Moreover, gaining insights into the role of cell-of-origin in glioblastoma treatment response holds the potential to advance precision medicine approaches. Addressing these challenges is crucial to improving outcomes for glioblastoma patients and moving towards more effective precision therapies.

Current knowledges in pharmaconutrition: "Ketogenics" in pediatric gliomas

Brain tumors account for 20-25% of pediatric cancers. The most frequent type of brain tumor is Glioma from grade I to grade IV according to the rate of malignancy. Current treatments for gliomas use chemotherapy, radiotherapy, tyrosine kinase inhibitors, monoclonal antibodies and surgery, but each of the treatment strategies has several serious side effects. Therefore, to improve treatment efficacy, it is necessary to tailor therapies to patient and tumor characteristics, using appropriate molecular targets. An increasingly popular strategy is pharmaconutrition, which combines a tailored pharmacological treatment with a diet designed to synergize the effects of drugs. In this review we deal in the molecular mechanisms, the epigenetic effects and modulation of the oxidative stress pathway of ketogenic diets, that underlie its possible role, in the treatment of infantile gliomas, as a complementary approach to conventional cancer therapy.

Role of nutritional adjuncts in the management of gliomas: A systematic review of literature

BACKGROUND

A variety of dietary adjuncts are known to affect the pathophysiology of glioma, making them a potential therapeutic adjunct to standard of care. We systematically reviewed clinical outcomes in glioma patients treated with one or more nutritional adjunct and/or an antimetabolite drug.

METHODOLOGY

A systematic review of the literature following PRISMA guidelines was performed using Pubmed from inception till February 2023. In total, 22 manuscripts on nutrition representing 828 patients were included in the review. Statistical analyses were performed to compare the outcomes of various adjuncts.

RESULTS

The median overall survival (OS) increased for newly diagnosed (21 months) and recurrent cases (10 months) when compared to historical data. For newly diagnosed cases, a ketogenic diet had the highest median OS of all the adjuncts (42.6 months) while in recurrent cases, a low copper diet coupled with 1 g penicillamine had the highest median OS (18.5 months). However, no statistically significant difference was observed in OS or progression-free survival (PFS) of newly diagnosed or recurrent gliomas.

CONCLUSION

While nutritional adjuncts may offer a therapeutic benefit in the treatment of glioma, more human subject research is needed to derive meaningful conclusions.

Lower dose of metformin combined with artesunate induced autophagy-dependent apoptosis of glioblastoma by activating ROS-AMPK-mTOR axis

Glioblastoma multiform (GBM), one of the most common, aggressive primary brain tumours, demonstrates resistance to radiotherapy and chemotherapy after surgical resection and treatment failure. Metformin (MET) has been shown to suppress the proliferative capacity and invasion ability of GBM cells by activating AMPK and inhibiting mTOR, but the effective dose exceeded the maximum tolerated dose. Artesunate (ART) can exert certain anti-tumour effects by activating the AMPK-mTOR axis and inducing autophagy in tumour cells. Therefore, this study investigated the effects of MET combined with ART combination therapy on autophagy and apoptosis in GBM cells. MET combined with ART treatment effectively suppressed the viability, mono-cloning ability, migration and invasion capacities, as well as metastatic ability of GBM cells. The underlying mechanism involved modulation of the ROS-AMPK-mTOR axis, which was confirmed using 3-methyladenine and rapamycin to inhibit or promote the effects of MET combined with ART, respectively. The study findings suggest that MET used in combination with ART can induce autophagy-dependent apoptosis in GBM cells by activating the ROS-AMPK-mTOR pathway, providing a potential new treatment for GBM.

Ketogenic diet in cancer management

PURPOSE OF REVIEW

This review presents details about types of ketogenic diet (KD), anticancer mechanisms, and the use of KD in experimental and clinical studies. Studies summarized in this review provide a solid ground for researchers to consider the use of KD to augment conventional treatments.

RECENT FINDINGS

KD is a dietary pattern composed of high fat, moderate proteins, and very-low-carbohydrate. This diet was suggested to have an anticancer effect and to augment conventional anticancer therapies. KD can target cancer cell by interfering with its metabolism without harming normal cells.

SUMMARY

Several experimental and clinical studies support the use of KD as adjuvant therapy to treat different cancers.

Could Metformin and Resveratrol Support Glioblastoma Treatment? A Mechanistic View at the Cellular Level

Glioblastoma, a malignant brain tumor, is a common primary brain tumor in adults, with diabetes mellitus being a crucial risk factor. This review examines how the antidiabetic drug metformin and dietary supplement resveratrol can benefit the treatment of glioblastoma. Metformin and resveratrol have demonstrated action against relevant pathways in cancer cells. Metformin and resveratrol inhibit cell proliferation by downregulating the PI3K/Akt pathway, activating mTOR, and increasing AMPK phosphorylation, resulting in lower proliferation and higher apoptosis levels. Metformin and resveratrol both upregulate and inhibit different cascades in the MAPK pathway. In vivo, the drugs reduced tumor growth and volume. These actions show how metformin and resveratrol can combat cancer with both glucose-dependent and glucose-independent effects. The pre-clinical results, alongside the lack of clinical studies and the rise in novel delivery mechanisms, warrant further clinical investigations into the applications of metformin and resveratrol as both separate and as a combination complement to current glioblastoma therapies.

Autophagic-Related Proteins in Brain Gliomas: Role, Mechanisms, and Targeting Agents

The present review focuses on the phenomenon of autophagy, a catabolic cellular process, which allows for the recycling of damaged organelles, macromolecules, and misfolded proteins. The different steps able to activate autophagy start with the formation of the autophagosome, mainly controlled by the action of several autophagy-related proteins. It is remarkable that autophagy may exert a double role as a tumour promoter and a tumour suppressor. Herein, we analyse the molecular mechanisms as well as the regulatory pathways of autophagy, mainly addressing their involvement in human astrocytic neoplasms. Moreover, the relationships between autophagy, the tumour immune microenvironment, and glioma stem cells are discussed. Finally, an excursus concerning autophagy-targeting agents is included in the present review in order to obtain additional information for the better treatment and management of therapy-resistant patients.

Drug Repurposing in Pediatric Brain Tumors: Posterior Fossa Ependymoma and Diffuse Midline Glioma under the Looking Glass

Tumors of the Central Nervous System (CNS) represent the leading cause of cancer-related deaths in children. Current treatment options are not curative for most malignant histologies, and intense preclinical and clinical research is needed to develop more effective therapeutic interventions against these tumors, most of which meet the FDA definition for orphan diseases. Increased attention is being paid to the repositioning of already-approved drugs for new anticancer indications as a fast-tracking strategy for identifying new and more effective therapies. Two pediatric CNS tumors, posterior fossa ependymoma (EPN-PF) type A and diffuse midline glioma (DMG) H3K27-altered, share loss of H3K27 trimethylation as a common epigenetic hallmark and display early onset and poor prognosis. These features suggest a potentially common druggable vulnerability. Successful treatment of these CNS tumors raises several challenges due to the location of tumors, chemoresistance, drug blood-brain barrier penetration, and the likelihood of adverse side effects. Recently, increasing evidence demonstrates intense interactions between tumor cell subpopulations and supportive tumor microenvironments (TMEs) including nerve, metabolic, and inflammatory TMEs. These findings suggest the use of drugs, and/or multi-drug combinations, that attack both tumor cells and the TME simultaneously. In this work, we present an overview of the existing evidence concerning the most preclinically validated noncancer drugs with antineoplastic activity. These drugs belong to four pharmacotherapeutic classes: antiparasitic, neuroactive, metabolic, and anti-inflammatory. Preclinical evidence and undergoing clinical trials in patients with brain tumors, with special emphasis on pediatric EPN-PF and DMG, are summarized and critically discussed.

The Potential Therapeutic Impact of Metformin in Glioblastoma Multiforme

In terms of frequency and aggressiveness, glioblastoma multiforme (GBM) is undoubtedly the most frequent and fatal primary brain tumor. Despite advances in clinical management, the response to current treatments is dismal, with a 2-year survival rate varying between 6 and 12 percent. Metformin, a derivative of biguanide widely used in treating type 2 diabetes, has been shown to extend the lifespan of patients with various malignancies. There is limited evidence available on the long-term survival of GBM patients who have taken metformin. This research examined the literature to assess the connection between metformin's anticancer properties and GBM development. Clinical findings, together with the preclinical data from animal models and cell lines, are included in the present review. This comprehensive review covers not only the association of hyperactivation of the AMPK pathway with the anticancer activity of metformin but also other mechanisms underpinning its role in apoptosis, cell proliferation, metastasis, as well as its chemo-radio-sensitizing behavior against GBM. Current challenges and future directions for developments and applications of metformin-based therapeutics are also discussed.

Ketogenic Diet in the Treatment of Gliomas and Glioblastomas

In recent years, scientific interest in the use of the ketogenic diet (KD) as a complementary approach to the standard cancer therapy has grown, in particular against those of the central nervous system (CNS). In metabolic terms, there are the following differences between healthy and neoplastic cells: neoplastic cells divert their metabolism to anaerobic glycolysis (Warburg effect), they alter the normal mitochondrial functioning, and they use mainly certain amino acids for their own metabolic needs, to gain an advantage over healthy cells and to lead to a pro-oncogenetic effect. Several works in literature speculate which are the molecular targets of KD used against cancer. The following different mechanisms of action will be explored in this review: metabolic, inflammatory, oncogenic and oncosuppressive, ROS, and epigenetic modulation. Preclinical and clinical studies on the use of KD in CNS tumors have also increased in recent years. An interesting hypothesis emerged from the studies about the possible use of a ketogenic diet as a combination therapy along with chemotherapy (CT) and radiotherapy (RT) for the treatment of cancer. Currently, however, clinical data are still very limited but encouraging, so we need further studies to definitively validate or disprove the role of KD in fighting against cancer.

Metformin with Temozolomide for Newly Diagnosed Glioblastoma: Results of Phase I Study and a Brief Review of Relevant Studies

Glioblastoma (GBM) inevitably recurs due to a resistance to current standard therapy. We showed that the antidiabetic drug metformin (MF) can induce the differentiation of stem-like glioma-initiating cells and suppress tumor formation through AMPK-FOXO3 activation. In this study, we design a phase I/II study to examine the clinical effect of MF. We aim to determine a recommended phase II MF dose with maintenance temozolomide (TMZ) in patients with newly diagnosed GBM who completed standard concomitant radiotherapy and TMZ. MF dose-escalation was planned using a 3 + 3 design. Dose-limiting toxicities (DLTs) were assessed during the first six weeks after MF initiation. Three patients were treated with 1500 mg/day MF and four patients were treated with 2250 mg/day MF between February 2021 and January 2022. No DLTs were observed. The most common adverse effects were appetite loss, nausea, and diarrhea, all of which were manageable. Two patients experienced tumor progression at 6.0 and 6.1 months, and one died 12.2 months after initial surgery. The other five patients remained stable at the last follow-up session. The MF dose of up to 2250 mg/day combined with maintenance TMZ appeared to be well tolerated, and we proceeded to a phase II study with 2250 mg/day MF.

Methodological Approaches to Ketogenic Dietary Treatments in Glioma Patients from a Nutritional Point of View

Ketogenic diets (KD) have received increasing interest in neuro-oncology based on their ability to inhibit glioma growth In Vitro and their established role in medically refractory seizures. This review analyses the methodological aspects of KD treatment alongside standard care for patients with gliomas from a nutritional point of view. A literature search was performed in March 2022 searching PubMed and Scopus. We identified 13 articles including 187 patients with a histological-new or recurrent-diagnosis of glioma and treated by KD during the course of the disease. Dietary treatments were categorized as the classical ketogenic diet (CKD), the Modified Atkins diet (MAD), and the medium-chain triglyceride (MCT) diet. We identified a large variation in dietary characteristics regarding restriction of carbohydrates, ketogenic ratio, and additional dietary support. This striking heterogenicity in the methodological approaches of KD treatments made it problematic to compare effects between the included studies. Therefore, a standardized definition of KD for patients with glioma and a consensus on methodological implementation is needed. It would also be desirable to further investigate to what extent KD treatment can be optimized to secure optimal nutrient status and patient satisfaction.

Long Term Survivals in Aggressive Primary Brain Malignancies Treated With an Adjuvant Ketogenic Diet

Aggressive primary brain tumors (APBT) glioblastoma multiforme and grade IV astrocytoma are treated with multimodality treatments that include surgery to remove as much tumor as possible without sacrificing neurological function followed by radiation therapy and chemotherapy usually temozolomide. Survivals in adults are in the range of 8–16 months. The addition of a ketogenic diet (KD) to rodents with transplanted brain tumors increased survival in nine of 11 animals to over 299 days compared to survival in untreated controls of 33 days and radiation only controls of 38 days. We treated humans with APBT with standard of care neurosurgery immediately followed by 6 weeks of an adjuvant ketogenic diet concurrent with radiation therapy and temozolomide. Twice daily measurements of blood ketones and glucose were recorded and the patients' diet was modified toward the goal of maintaining blood ketone levels approaching 3 mM. Of the nine patients who completed the protocol three younger patients age 32, 28, and 22 at enrollment are alive and employed with clinically stable disease and brain images 74, 58, and 52 months since diagnosis. All the six older patients mean age 55 have died with disease progression detected on average 8 months after Dx. In conclusion: 1. It is possible to implement and maintain dietary induced ketosis in patients with APBT; 2. The longer survivals observed in younger patients treated with KD need to be confirmed in larger studies that should be focused on younger patients possibly under age 40.

Serum metabolomic analysis of men on a low-carbohydrate diet for biochemically recurrent prostate cancer reveals the potential role of ketogenesis to slow tumor growth: a secondary analysis of the CAPS2 diet trial

BACKGROUND

Systemic treatments for prostate cancer (PC) have significant side effects. Thus, newer alternatives with fewer side effects are urgently needed. Animal and human studies suggest the therapeutic potential of low carbohydrate diet (LCD) for PC. To test this possibility, Carbohydrate and Prostate Study 2 (CAPS2) trial was conducted in PC patients with biochemical recurrence (BCR) after local treatment to determine the effect of a 6-month LCD intervention vs. usual care control on PC growth as measured by PSA doubling time (PSADT). We previously reported the LCD intervention led to significant weight loss, higher HDL, and lower triglycerides and HbA1c with a suggested longer PSADT. However, the metabolic basis of these effects are unknown.

METHODS

To identify the potential metabolic basis of effects of LCD on PSADT, serum metabolomic analysis was performed using baseline, month 3, and month 6 banked sera to identify the metabolites significantly altered by LCD and that correlated with varying PSADT.

RESULTS

LCD increased the serum levels of ketone bodies, glycine and hydroxyisocaproic acid. Reciprocally, LCD reduced the serum levels of alanine, cytidine, asymmetric dimethylarginine (ADMA) and 2-oxobutanoate. As high ADMA level is shown to inhibit nitric oxide (NO) signaling and contribute to various cardiovascular diseases, the ADMA repression under LCD may contribute to the LCD-associated health benefit. Regression analysis of the PSADT revealed a correlation between longer PSADT with higher level of 2-hydroxybutyric acids, ketone bodies, citrate and malate. Longer PSADT was also associated with LCD reduced nicotinamide, fructose-1, 6-biphosphate (FBP) and 2-oxobutanoate.

CONCLUSION

These results suggest a potential association of ketogenesis and TCA metabolites with slower PC growth and conversely glycolysis with faster PC growth. The link of high ketone bodies with longer PSADT supports future studies of ketogenic diets to slow PC growth.

The efficacy of an unrestricted cycling ketogenic diet in preclinical models of IDH wild-type and IDH mutant glioma

Infiltrative gliomas are the most common neoplasms arising in the brain, and remain largely incurable despite decades of research. A subset of these gliomas contains mutations in isocitrate dehydrogenase 1 (IDH1^mut) or, less commonly, IDH2 (together called “IDH^mut”). These mutations alter cellular biochemistry, and IDH^mut gliomas are generally less aggressive than IDH wild-type (IDH^wt) gliomas. Some preclinical studies and clinical trials have suggested that various forms of a ketogenic diet (KD), characterized by low-carbohydrate and high-fat content, may be beneficial in slowing glioma progression. However, adherence to a strict KD is difficult, and not all studies have shown promising results. Furthermore, no study has yet addressed whether IDH^mut gliomas might be more sensitive to KD. The aim of the current study was to compare the effects of a unrestricted, cycling KD (weekly alternating between KD and standard diet) in preclinical models of IDH^wt versus IDH^mut gliomas. In vitro, simulating KD by treatment with the ketone body β-hydroxybutyrate had no effect on the proliferation of patient-derived IDH^wt or IDH^mut glioma cells, either in low or normal glucose conditions. Likewise, an unrestricted, cycling KD had no effect on the in vivo growth of patient-derived IDH^wt or IDH^mut gliomas, even though the cycling KD did result in persistently elevated circulating ketones. Furthermore, this KD conferred no survival benefit in mice engrafted with Sleeping-Beauty transposase-engineered IDH^mut or IDH^wt glioma. These data suggest that neither IDH^wt nor IDH^mut gliomas are particularly responsive to an unrestricted, cycling form of KD.

Ketogenic Diet for Cancer: Critical Assessment and Research Recommendations

Despite remarkable improvements in screening, diagnosis, and targeted therapies, cancer remains the second leading cause of death in the United States. It is increasingly clear that diet and lifestyle practices play a substantial role in cancer development and progression. As such, various dietary compositions have been proposed for reducing cancer risk and as potential adjuvant therapies. In this article, we critically assess the preclinical and human trials on the effects of the ketogenic diet (KD, i.e., high-fat, moderate-to-low protein, and very-low carbohydrate content) for cancer-related outcomes. The mechanisms underlying the hypothesized effects of KD, most notably the Warburg Effect, suggest that restricting carbohydrate content may impede cancer development and progression via several pathways (e.g., tumor metabolism, gene expression). Overall, although preclinical studies suggest that KD has antitumor effects, prolongs survival, and prevents cancer development, human clinical trials are equivocal. Because of the lack of high-quality clinical trials, the effects of KD on cancer and as an adjunctive therapy are essentially unknown. We propose a set of research recommendations for clinical studies examining the effects of KD on cancer development and progression.

Metformin Is Associated with a Lower Incidence of Benign Brain Tumors: A Retrospective Cohort Study in Patients with Type 2 Diabetes Mellitus

Background: The risk of benign brain tumors (BBT) associated with metformin use has not received much attention. Therefore, a retrospective cohort study was designed to investigate such an association in patients with type 2 diabetes mellitus (T2DM). Methods: We used the database of Taiwan's National Health Insurance to enroll 152,176 ever users and 16,120 never users of metformin for the follow-up of incidence of BBT and a more specific outcome of cerebral meningioma. The patients were newly diagnosed with T2DM between 1999 and 2005; and they were followed up from 1 January 2006 until 31 December 2011. Hazard ratios were estimated by Cox regression incorporated with the inverse probability of treatment weighting using propensity score. Results: During follow-up, 111 never users and 557 ever users were diagnosed with BBT. For BBT, the respective incidence rates for never users and ever users were 153.95 per 100,000 person-years and 77.61 per 100,000 person-years. While ever users were compared to never users, the hazard ratio was 0.502 (95% confidence interval: 0.409-0.615). A dose-response pattern was seen when ever users were categorized into tertiles of cumulative duration of metformin therapy (cutoffs: <27.10 months, 27.10-58.27 months and >58.27 months) with respective hazard ratios of 0.910 (0.728-1.138), 0.475 (0.375-0.602) and 0.243 (0.187-0.315). For cerebral meningioma, the overall hazard ratio was 0.506 (0.317-0.808); and the hazard ratios comparing the respective tertiles to never users were 0.895 (0.531-1.508), 0.585 (0.346-0.988) and 0.196 (0.104-0.369). Conclusions: A reduced risk of BBT and cerebral meningioma is observed in metformin users in patients with T2DM.

Dietary-Induced Ketogenesis: Adults Are Not Children

There is increasing interest in the use of a ketogenic diet for various adult disorders; however, the ability of adults to generate ketones is unknown. Our goal was to challenge the hypothesis that there would be no difference between adults and children regarding their ability to enter ketosis. Methods: Two populations were studied, both treated with identical very low-carbohydrate high-fat diets: a retrospective series of children with epilepsy or/and metabolic disorders (2009–2016) and a prospective clinical trial of adults with glioblastoma. Dietary intake was assessed based upon written food diaries and 24-h dietary recall. Ketogenic ratio was calculated according to [grams of fat consumed]/[grams of carbohydrate and protein consumed]. Ketone levels (β-hydroxybutyrate) were measured in blood and/or urine. Results: A total of 168 encounters amongst 28 individuals were analyzed. Amongst both children and adults, ketone levels correlated with nutritional ketogenic ratio; however, the absolute ketone levels in adults were approximately one quarter of those seen in children. This difference was highly significant in a multivariate linear regression model, p < 0.0001. Conclusions: For diets with comparable ketogenic ratios, adults have lower blood ketone levels than children; consequently, high levels of nutritional ketosis are unobtainable in adults.

Radiotherapy of High-Grade Gliomas: First Half of 2021 Update with Special Reference to Radiosensitization Studies

Albeit the effort to develop targeted therapies for patients with high-grade gliomas (WHO grades III and IV) is evidenced by hundreds of current clinical trials, radiation remains one of the few effective therapeutic options for them. This review article analyzes the updates on the topic "radiotherapy of high-grade gliomas" during the period 1 January 2021-30 June 2021. The high number of articles retrieved in PubMed using the search terms ("gliom* and radio*") and manually selected for relevance indicates the feverish research currently ongoing on the subject. During the last semester, significant advances were provided in both the preclinical and clinical settings concerning the diagnosis and prognosis of high-grade gliomas, their radioresistance, and the inevitable side effects of their treatment with radiation. The novel information concerning tumor radiosensitization was of special interest in terms of therapeutic perspective and was discussed in detail.

Metformin and Risk of Malignant Brain Tumors in Patients with Type 2 Diabetes Mellitus

The risk of malignant brain tumors associated with metformin use has rarely been investigated in humans. This retrospective cohort study investigated such an association. Patients with new-onset type 2 diabetes mellitus diagnosed from 1999 to 2005 in the nationwide database of Taiwan's national health insurance were used to enroll study subjects. We first identified an unmatched cohort of 153,429 ever users and 16,222 never users of metformin. A cohort of 16,222 ever users and 16,222 never users matched on propensity score was then created from this unmatched cohort. All patients were followed up from 1 January 2006 until 31 December 2011. The incidence density was calculated and hazard ratios were derived from Cox regression incorporated with the inverse probability of treatment weighting using a propensity score. The results showed that 27 never users and 155 ever users developed malignant brain tumors in the unmatched cohort. The incidence rate was 37.11 per 100,000 person-years in never users and 21.39 per 100,000 person-years in ever users. The overall hazard ratio comparing ever users versus never users was 0.574 (95% confidence interval: 0.381-0.863). The respective hazard ratios comparing the first (<27.13 months), second (27.13-58.33 months), and third (>58.33 months) tertiles of cumulative duration of metformin therapy versus never users were 0.897 (0.567-1.421), 0.623 (0.395-0.984), and 0.316 (0.192-0.518). In the matched cohort, the overall hazard ratio was 0.317 (0.149-0.673) and the respective hazard ratios were 0.427 (0.129-1.412), 0.509 (0.196-1.322), and 0.087 (0.012-0.639) for the first, second, and third tertile of cumulative duration of metformin therapy. In conclusion, this study shows a risk reduction of malignant brain tumors associated with metformin use in a dose-response pattern. The risk reduction is more remarkable when metformin has been used for approximately 2-5 years.