A randomized phase II study of everolimus in combination with chemoradiation in newly diagnosed glioblastoma: results of NRG Oncology RTOG 0913

Tumor treating fields for newly diagnosed high-grade glioma based on the criteria of 2021 WHO CNS5: A retrospective analysis of Chinese patients in a single center

BACKGROUND AND OBJECTIVE

High-grade glioma (HGG) is known to be characterized by a high degree of malignancy and a worse prognosis. The classical treatment is safe resection supplemented by radiotherapy and chemotherapy. Tumor treating fields (TTFields), an emerging physiotherapeutic modality that targets malignant solid tumors using medium-frequency, low-intensity, alternating electric fields to interfere with cell division, have been used for the treatment of new diagnosis of glioblastoma, however, their administration in HGG requires further clinical evidence. The efficacy and safety of TTFields in Chinese patients with HGG were retrospectively evaluated by us in a single center.

METHODS

We enrolled and analyzed 52 patients with newly diagnosed HGG undergoing surgery and standard chemoradiotherapy regimens from December 2019 to June 2022, and followed them until June 2023. Based on whether they used TTFields, they were divided into a TTFields group and a non-TTFields group. Progression-free survival (PFS) and overall survival (OS) were compared between the two groups.

RESULTS

There were 26 cases in the TTFields group and 26 cases in the non-TTFields group. In the TTFields group, the median PFS was 14.2 months (95% CI: 9.50-18.90), the median OS was 19.7 months (95% CI: 14.95-24.25) , the median interval from surgery to the start of treatment with TTFields was 2.47 months (95% CI: 1.47-4.13), and the median duration of treatment with TTFields was 10.6 months (95% CI: 9.57-11.63). 15 (57.69%) patients experienced an adverse event and no serious adverse event was reported. In the non-TTFields group, the median PFS was 9.57 months (95% CI: 6.23-12.91) and the median OS was 16.07 months (95% CI: 12.90-19.24). There was a statistically significant difference in PFS (p = 0.005) and OS (p = 0.007) between the two groups.

CONCLUSIONS

In this retrospective analysis, TTFields were observed to improve newly diagnosed HGG patients' median PFS and OS. Compliance was much higher than reported in clinical trials and safety remained good.

Glioblastoma Therapy: Past, Present and Future

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

Advances in functional lipid nanoparticles: from drug delivery platforms to clinical applications

Since Doxil's first clinical approval in 1995, lipid nanoparticles have garnered great interest and shown exceptional therapeutic efficacy. It is clear from the licensure of two RNA treatments and the mRNA-COVID-19 vaccination that lipid nanoparticles have immense potential for delivering nucleic acids. The review begins with a list of lipid nanoparticle types, such as liposomes and solid lipid nanoparticles. Then it moves on to the earliest lipid nanoparticle forms, outlining how lipid is used in a variety of industries and how it is used as a versatile nanocarrier platform. Lipid nanoparticles must then be functionally modified. Various approaches have been proposed for the synthesis of lipid nanoparticles, such as High-Pressure Homogenization (HPH), microemulsion methods, solvent-based emulsification techniques, solvent injection, phase reversal, and membrane contractors. High-pressure homogenization is the most commonly used method. All of the methods listed above follow four basic steps, as depicted in the flowchart below. Out of these four steps, the process of dispersing lipids in an aqueous medium to produce liposomes is the most unpredictable step. A short outline of the characterization of lipid nanoparticles follows discussions of applications for the trapping and transporting of various small molecules. It highlights the use of rapamycin-coated lipid nanoparticles in glioblastoma and how lipid nanoparticles function as a conjugator in the delivery of anticancer-targeting nucleic acids. High biocompatibility, ease of production, scalability, non-toxicity, and tailored distribution are just a meager of the enticing allowances of using lipid nanoparticles as drug delivery vehicles. Due to the present constraints in drug delivery, more research is required to utterly realize the potential of lipid nanoparticles for possible clinical and therapeutic purposes.

Mammalian target of rapamycin inhibition protects glioma cells from temozolomide-induced cell death

Glioblastoma is an incurable brain tumor with a median survival below two years. Trials investigating targeted therapy with inhibitors of the kinase mTOR have produced ambiguous results. Especially combination of mTOR inhibition with standard temozolomide radiochemotherapy has resulted in reduced survival in a phase II clinical trial. To date, this phenomenon is only poorly understood. To recreate the therapeutic setting in vitro, we exposed glioblastoma cell lines to co-treatment with rapamycin and temozolomide and assessed cell viability, DNA damage and reactive oxygen species. Additionally, we employed a novel translatomic based mass spectrometry approach ("mePROD") to analyze acute changes in translated proteins. mTOR inhibition with rapamycin protected glioblastoma cells from temozolomide toxicity. Following co-treatment of temozolomide with rapamycin, an increased translation of reactive oxygen species (ROS)-detoxifying proteins was detected by mass spectrometry. This was accompanied by improved ROS-homeostasis and reduced DNA damage. Additionally, rapamycin induced the expression of the DNA repair enzyme O-6-methylguanine-DNA methyltransferase (MGMT) in glioblastoma cells with an unmethylated MGMT gene promotor. Inhibition of mTOR antagonized the cytotoxic effects of temozolomide in vitro. The induction of antioxidant defences and MGMT are two underlying candidate mechanisms. Further functional experiments in vitro and in vivo are warranted to characterize this effect that appears relevant for combinatorial therapeutic strategies.

Gene signatures associated with prognosis and chemotherapy resistance in glioblastoma treated with temozolomide

Background: Glioblastoma (GBM) prognosis remains extremely poor despite standard treatment that includes temozolomide (TMZ) chemotherapy. To discover new GBM drug targets and biomarkers, genes signatures associated with survival and TMZ resistance in GBM patients treated with TMZ were identified. Methods: GBM cases in The Cancer Genome Atlas who received TMZ (n = 221) were stratified into subgroups that differed by median overall survival (mOS) using network-based stratification to cluster patients whose somatic mutations affected genes in similar modules of a gene interaction network. Gene signatures formed from differentially mutated genes in the subgroup with the longest mOS were used to confirm their association with survival and TMZ resistance in independent datasets. Somatic mutations in these genes also were assessed for an association with OS in an independent group of 37 GBM cases. Results: Among the four subgroups identified, subgroup four (n = 71 subjects) exhibited the longest mOS at 18.3 months (95% confidence interval: 16.2, 34.1; p = 0.0324). Subsets of the 86 genes that were differentially mutated in this subgroup formed 20-gene and 8-gene signatures that predicted OS in two independent datasets (Spearman's rho of 0.64 and 0.58 between actual and predicted OS; p < 0.001). Patients with mutations in five of the 86 genes had longer OS in a small, independent sample of 37 GBM cases, but this association did not reach statistical significance (p = 0.07). Thirty-one of the 86 genes formed signatures that distinguished TMZ-resistant GBM samples from controls in three independent datasets (area under the curve ≥ 0.75). The prognostic and TMZ-resistance signatures had eight genes in common (ANG, BACH1, CDKN2C, HMGA1, IFI16, PADI4, SDF4, and TP53INP1). The latter three genes have not been associated with GBM previously. Conclusion: PADI4, SDF4, and TP53INP1 are novel therapy and biomarker candidates for GBM. Further investigation of their oncologic functions may provide new insight into GBM treatment resistance mechanisms.

Tumor Niches: Perspectives for Targeted Therapies in Glioblastoma

Significance: Glioblastoma (GBM), the most common and lethal primary brain tumor with a median survival rate of only 15 months and a 5-year survival rate of only 6.8%, remains largely incurable despite the intensive multimodal treatment of surgical resection and radiochemotherapy. Developing effective new therapies is an unmet need for patients with GBM. Recent Advances: Targeted therapies, such as antiangiogenesis therapy and immunotherapy, show great promise in treating GBM based upon increasing knowledge about brain tumor biology. Single-cell transcriptomics reveals the plasticity, heterogeneity, and dynamics of tumor cells during GBM development and progression. Critical Issues: While antiangiogenesis therapy and immunotherapy have been highly effective in some types of cancer, the disappointing results from clinical trials represent continued challenges in applying these treatments to GBM. Molecular and cellular heterogeneity of GBM is developed temporally and spatially, which profoundly contributes to therapeutic resistance and tumor recurrence. Future Directions: Deciphering mechanisms of tumor heterogeneity and mapping tumor niche trajectories and functions will provide a foundation for the development of more effective therapies for GBM patients. In this review, we discuss five different tumor niches and the intercellular and intracellular communications among these niches, including the perivascular, hypoxic, invasive, immunosuppressive, and glioma-stem cell niches. We also highlight the cellular and molecular biology of these niches and discuss potential strategies to target these tumor niches for GBM therapy. Antioxid. Redox Signal. 39, 904-922.

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.

Combined cytotoxic and immune-stimulatory gene therapy using Ad-TK and Ad-Flt3L: Translational developments from rodents to glioma patients

Gliomas are the most prevalent and devastating primary malignant brain tumors in adults. Despite substantial advances in understanding glioma biology, there have been no regulatory drug approvals in the US since bevacizumab in 2009 and tumor treating fields in 2011. Recent phase III clinical trials have failed to meet their prespecified therapeutic primary endpoints, highlighting the need for novel therapies. The poor prognosis of glioma patients, resistance to chemo-radiotherapy, and the immunosuppressive tumor microenvironment underscore the need for the development of novel therapies. Gene therapy-based immunotherapeutic strategies that couple the ability of the host immune system to specifically kill glioma cells and develop immunological memory have shown remarkable progress. Two adenoviral vectors expressing Ad-HSV1-TK/GCV and Ad-Flt3L have shown promising preclinical data, leading to FDA approval of a non-randomized, phase I open-label, first in human trial to test safety, cytotoxicity, and immune-stimulatory efficiency in high-grade glioma patients (NCT01811992). This review provides a thorough overview of immune-stimulatory gene therapy highlighting recent advancements, potential drawbacks, future directions, and recommendations for future implementation of clinical trials.

Metformin use is associated with longer survival in glioblastoma patients with MGMT gene silencing

PURPOSE

New treatments are needed to improve the overall survival of patients with glioblastoma Metformin is known for anti-tumorigenic effects in cancers, including breast and pancreas cancers. In this study, we assessed the association between metformin use and overall survival in glioblastoma patients.

METHODS

We retrospectively studied 241 patients who underwent surgery at diagnosis of glioblastoma between 2014 and 2018. Metformin was used for pre-existing type 2 diabetes mellitus or in the prevention or management of glucocorticoid induced hyperglycemia. Kaplan-Meier curves and log-rank p test were used for univariate analysis. Cox-proportional hazards model was used to generate adjusted hazard ratios for multivariate analysis.

RESULTS

Metformin use was associated with longer survival in patients with tumors that had a methylated O6-methylguanine DNA methyltransferase gene (MGMT) promoter (484 days 95% CI: 56-911 vs. 394 days 95% CI: 249-538, Log-Rank test: 6.5, p = 0.01). Cox regression analysis shows that metformin associates with lower risk of death at 2 years in patients with glioblastoma containing a methylated MGMT promoter (aHR = 0.497, 95% CI 0.26-0.93, p = 0.028).

CONCLUSION

Our findings suggest a survival benefit with metformin use in patients with glioblastomas having methylation of the MGMT promoter.

An introductory review of post-resection chemotherapeutics for primary brain tumors

The treatment of central nervous system (CNS) tumors is complicated by high rates of recurrence and treatment resistance that contribute to high morbidity and mortality (Nat Rev Neurol. 2022;18:221-36. doi: 10.1038/s41582-022-00621-0). One of the challenges of treating these tumors is the limited permeability of the blood brain barrier (BBB). Early pharmacologic treatments worked to overcome the BBB by targeting vulnerabilities in the tumor cell replication process directly through alkylating agents like temozolomide. However, as advancements have been made options have expanded to include immunologic targets through the use of monoclonal antibodies. In the future, treatment will likely continue to focus on the use of immunotherapies, as well as emerging technology like the use of low-intensity focused ultrasound (LIFU). Ultimately, this paper serves as an introductory overview of current therapeutic options for post-resection primary brain tumors, as well as a look towards future work and emerging treatment options.

Repurposing FDA-approved drugs as inhibitors of therapy-induced invadopodia activity in glioblastoma cells

Glioblastoma (GBM) is the most prevalent primary central nervous system tumour in adults. The lethality of GBM lies in its highly invasive, infiltrative, and neurologically destructive nature resulting in treatment failure, tumour recurrence and death. Even with current standard of care treatment with surgery, radiotherapy and chemotherapy, surviving tumour cells invade throughout the brain. We have previously shown that this invasive phenotype is facilitated by actin-rich, membrane-based structures known as invadopodia. The formation and matrix degrading activity of invadopodia is enhanced in GBM cells that survive treatment. Drug repurposing provides a means of identifying new therapeutic applications for existing drugs without the need for discovery or development and the associated time for clinical implementation. We investigate several FDA-approved agents for their ability to act as both cytotoxic agents in reducing cell viability and as 'anti-invadopodia' agents in GBM cell lines. Based on their cytotoxicity profile, three agents were selected, bortezomib, everolimus and fludarabine, to test their effect on GBM cell invasion. All three drugs reduced radiation/temozolomide-induced invadopodia activity, in addition to reducing GBM cell viability. These drugs demonstrate efficacious properties warranting further investigation with the potential to be implemented as part of the treatment regime for GBM.

Comparative dosimetric study of radiotherapy in high-grade gliomas based on the guidelines of EORTC and NRG-2019 target delineation

Purpose

Radiotherapy is one of the most important treatments for high-grade glioma (HGG), but the best way to delineate the target areas for radiotherapy remains controversial, so our aim was to compare the dosimetric differences in radiation treatment plans generated based on the European Organization for Research and Treatment of Cancer (EORTC) and National Research Group (NRG) consensus to provide evidence for optimal target delineation for HGG.

Methods

We prospectively enrolled 13 patients with a confirmed HGG from our hospital and assessed dosimetric differences in radiotherapy treatment plans generated according to the EORTC and NRG-2019 guidelines. For each patient, two treatment plans were generated. Dosimetric parameters were compared by dose-volume histograms for each plan.

Results

The median volume for planning target volume (PTV) of EORTC plans, PTV1 of NRG-2019 plans, and PTV2 of NRG-2019 plans were 336.6 cm³ (range, 161.1-511.5 cm³), 365.3 cm³ (range, 123.4-535.0 cm³), and 263.2 cm³ (range, 116.8-497.7 cm³), respectively. Both treatment plans were found to have similar efficiency and evaluated as acceptable for patient treatment. Both treatment plans showed well conformal index and homogeneity index and were not statistically significantly different (P = 0.397 and P = 0.427, respectively). There was no significant difference in the volume percent of brain irradiated to 30, 46, and 60 Gy according to different target delineations (P = 0.397, P = 0.590, and P = 0.739, respectively). These two plans also showed no significant differences in the doses to the brain stem, optic chiasm, left and right optic nerves, left and right lens, left and right eyes, pituitary, and left and right temporal lobes (P = 0.858, P = 0.858, P = 0.701 and P = 0.794, P = 0.701 and P = 0.427, P = 0.489 and P = 0.898, P = 0.626, and P = 0.942 and P = 0.161, respectively).

Conclusion

The NRG-2019 project did not increase the dose of organs at risk (OARs) radiation. This is a significant finding that further lays the groundwork for the application of the NRG-2019 consensus in the treatment of patients with HGGs.

Clinical trial registration

The effect of radiotherapy target area and glial fibrillary acidic protein (GFAP) on the prognosis of high-grade glioma and its mechanism, number ChiCTR2100046667. Registered 26 May 2021.

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.

Design, Synthesis, and Biological Evaluation of Sulfonamide Methoxypyridine Derivatives as Novel PI3K/mTOR Dual Inhibitors

Phosphatidylinositol 3-kinase (PI3K) plays an important role in cell proliferation, survival, migration, and metabolism, and has become an effective target for cancer treatment. Meanwhile, inhibiting both PI3K and mammalian rapamycin receptor (mTOR) can simultaneously improve the efficiency of anti-tumor therapy. Herein, a series of 36 sulfonamide methoxypyridine derivatives with three different aromatic skeletons were synthesized as novel potent PI3K/mTOR dual inhibitors based on a scaffold hopping strategy. Enzyme inhibition assay and cell anti-proliferation assay were employed to assess all derivatives. Then, the effects of the most potent inhibitor on cell cycle and apoptosis were performed. Furthermore, the phosphorylation level of AKT, an important downstream effector of PI3K, was evaluated by Western blot assay. Finally, molecular docking was used to confirm the binding mode with PI3Kα and mTOR. Among them, 22c with the quinoline core showed strong PI3Kα kinase inhibitory activity (IC₅₀ = 0.22 nM) and mTOR kinase inhibitory activity (IC₅₀ = 23 nM). 22c also showed a strong proliferation inhibitory activity, both in MCF-7 cells (IC₅₀ = 130 nM) and HCT-116 cells (IC₅₀ = 20 nM). 22c could effectively cause cell cycle arrest in G0/G1 phase and induce apoptosis of HCT-116 cells. Western blot assay showed that 22c could decrease the phosphorylation of AKT at a low concentration. The results of the modeling docking study also confirmed the binding mode of 22c with PI3Kα and mTOR. Hence, 22c is a promising PI3K/mTOR dual inhibitor, which is worthy of further research in the area.

Radiation therapy-induced left vocal cord paralysis following lung stereotactic body radiation therapy: A case report and review of the literature

We report the case of a 50-year old women with an oncological history of metastatic breast carcinoma who underwent lung stereotactic body radiation therapy (SBRT) of 60Gy in 8 fractions for a left upper lobe metastatic lesion. Seven months later, she complains about hoarseness and weakness of voice. Tumoral relapse and other frequent etiologies were excluded. The diagnosis of radiation induced left recurrent laryngeal nerve paralysis causing left vocal cord paralysis (VCP) was made. The symptomatology did not improve till the disease progression and death of the patient 29 months after SBRT. VCP after lung SBRT is a rare adverse event that has not yet been well described in the medical literature.

Tailored therapy for recurrent glioblastoma: report of a personalized molecular approach

BACKGROUND

Failure of clinical trials with targeted therapies in glioblastoma (GBM) is probably related to the enrollment of molecularly unselected patients. In this study we report the results of a precision medicine protocol in recurrent GBM.

METHODS

We prospectively evaluated 34 patients with recurrent GBM. We determined the expression of vascular endothelial growth factor (VEGF), epidermal growth factor receptor variant III (EGFRvIII), and phosphatase and tensin homolog (PTEN). According to the molecular pattern we administered bevacizumab alone in patients with VEGF overexpression, absence of EGFRvIII, and normal PTEN (group A; N.=16); bevacizumab + erlotinib in patients with VEGF overexpression, expression of EGFRvIII, and normal PTEN (group B; N.=14); and bevacizumab + sirolimus in patients with VEGF overexpression and loss of PTEN, irrespective of the EGFRvIII status (group C; N.=4). We evaluated the response rate, the clinical benefit rate, the 6-month progression-free survival (PFS-6), the 12-month PFS (PFS-12) and the safety profile of the treatment. Moreover, we compared our results with the ones of EORTC 26101 trial.

RESULTS

Response rate was 50% in the whole cohort with the highest rate in group C (75%). Clinical benefit rate was 71% with the highest rate in group C (75%). PFS-6 was 56% in the whole cohort with the highest rate in group B (64%). PFS-12 was 21% in the whole cohort with the highest rate in group B (29%). When comparing our results with those from the combination arm of the EORTC 26101 trial we found a significantly higher PFS-6 and PFS-12 in our cohort.

CONCLUSIONS

The precision medicine protocol for recurrent GBM is feasible and leads to improved results if compared with studies lacking molecular selection.

Glioblastoma and the search for non-hypothesis driven combination therapeutics in academia

Glioblastoma (GBM) remains a cancer of high unmet clinical need. Current standard of care for GBM, consisting of maximal surgical resection, followed by ionisation radiation (IR) plus concomitant and adjuvant temozolomide (TMZ), provides less than 15-month survival benefit. Efforts by conventional drug discovery to improve overall survival have failed to overcome challenges presented by inherent tumor heterogeneity, therapeutic resistance attributed to GBM stem cells, and tumor niches supporting self-renewal. In this review we describe the steps academic researchers are taking to address these limitations in high throughput screening programs to identify novel GBM combinatorial targets. We detail how they are implementing more physiologically relevant phenotypic assays which better recapitulate key areas of disease biology coupled with more focussed libraries of small compounds, such as drug repurposing, target discovery, pharmacologically active and novel, more comprehensive anti-cancer target-annotated compound libraries. Herein, we discuss the rationale for current GBM combination trials and the need for more systematic and transparent strategies for identification, validation and prioritisation of combinations that lead to clinical trials. Finally, we make specific recommendations to the preclinical, small compound screening paradigm that could increase the likelihood of identifying tractable, combinatorial, small molecule inhibitors and better drug targets specific to GBM.

Targeted therapies in patients with newly diagnosed glioblastoma-A systematic meta-analysis of randomized clinical trials

Glioblastoma (GB) is the most common malignant primary brain tumor in adults. The standard of care for newly diagnosed GB involves surgical resection followed by radiochemotherapy with temozolomide, with or without tumor-treating fields. In recent years, various efforts have been made to identify suitable molecularly targeted treatment options for malignant brain tumors. This meta-analysis provides an overview of recently published randomized controlled trials (RCTs) with and without molecular stratification, analyzing targeted agents in patients with newly diagnosed GB. The Cochrane Library, MEDLINE (Ovid), ClinicalTrials.gov, WHO's International Clinical Trials Registry Platform, and Google Scholar were searched for RCTs on targeted therapies in patients with newly diagnosed glioblastoma. Hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS) were extracted and pooled in a random-effects meta-analysis. Twelve RCTs (n = 3941 patients) involving protein kinase inhibitors, proteasome and histone deacetylase inhibitors, anti-angiogenic approaches and poly (ADP-ribose) polymerase (PARP) inhibitors were included in the meta-analysis. None of the targeted agents achieved a significant benefit with regard to OS (HR = 0.98 [95% confidence interval (CI) 0.86-1.11, P = .7731]). By comparison, targeted therapy showed a benefit for PFS (HR = 0.83 [95% CI 0.74-0.94, P = .0037]), especially for patients with an unmethylated O6-methylguanine-DNA-methyltransferase (MGMT) promoter (0.75 [95% CI 0.56-0.99, P = .0440]). Prolongation of PFS was largely driven by VEGF inhibition with bevacizumab (HR = 0.70 [95% CI 0.61-0.80, P = .0000]). VEGF inhibition with bevacizumab prolonged PFS in patients with newly diagnosed glioblastoma compared to standard care. However, no improvement in OS was observed with any of the targeted agents.

Clinically relevant glioblastoma patient-derived xenograft models to guide drug development and identify molecular signatures

Glioblastoma (GBM) heterogeneity, aggressiveness and infiltrative growth drastically limit success of current standard of care drugs and efficacy of various new therapeutic approaches. There is a need for new therapies and models reflecting the complex biology of these tumors to analyze the molecular mechanisms of tumor formation and resistance, as well as to identify new therapeutic targets. We established and screened a panel of 26 patient-derived subcutaneous (s.c.) xenograft (PDX) GBM models on immunodeficient mice, of which 15 were also established as orthotopic models. Sensitivity toward a drug panel, selected for their different modes of action, was determined. Best treatment responses were observed for standard of care temozolomide, irinotecan and bevacizumab. Matching orthotopic models frequently show reduced sensitivity, as the blood-brain barrier limits crossing of the drugs to the GBM. Molecular characterization of 23 PDX identified all of them as IDH-wt (R132) with frequent mutations in EGFR, TP53, FAT1, and within the PI3K/Akt/mTOR pathway. Their expression profiles resemble proposed molecular GBM subtypes mesenchymal, proneural and classical, with pronounced clustering for gene sets related to angiogenesis and MAPK signaling. Subsequent gene set enrichment analysis identified hallmark gene sets of hypoxia and mTORC1 signaling as enriched in temozolomide resistant PDX. In models sensitive for mTOR inhibitor everolimus, hypoxia-related gene sets reactive oxygen species pathway and angiogenesis were enriched. Our results highlight how our platform of s.c. GBM PDX can reflect the complex, heterogeneous biology of GBM. Combined with transcriptome analyses, it is a valuable tool in identification of molecular signatures correlating with monitored responses. Available matching orthotopic PDX models can be used to assess the impact of the tumor microenvironment and blood-brain barrier on efficacy. Our GBM PDX panel therefore represents a valuable platform for screening regarding molecular markers and pharmacologically active drugs, as well as optimizing delivery of active drugs to the tumor.

Inhibition of mTOR signaling protects human glioma cells from hypoxia-induced cell death in an autophagy-independent manner

Although malignant gliomas frequently show aberrant activation of the mammalian target of rapamycin (mTOR), mTOR inhibitors have performed poorly in clinical trials. Besides regulating cell growth and translation, mTOR controls the initiation of autophagy. By recycling cellular components, autophagy can mobilize energy resources, and has thus been attributed cancer-promoting effects. Here, we asked whether the activation of autophagy represents an escape mechanism to pharmacological mTOR inhibition in glioma cells, and explored co-treatment with mTOR and autophagy inhibitors as a therapeutic strategy. Mimicking conditions of the glioma microenvironment, glioma cells were exposed to nutrient starvation and hypoxia. We analyzed autophagic activity, cell growth, viability and oxygen consumption following (co-)treatment with the mTOR inhibitors torin2 or rapamycin, and autophagy inhibitors bafilomycin A1 or MRT68921. Changes in global proteome were quantified by mass spectrometry. In the context of hypoxia and starvation, autophagy was strongly induced in glioma cells and further increased by mTOR inhibition. While torin2 enhanced glioma cell survival, co-treatment with torin2 and bafilomycin A1 failed to promote cell death. Importantly, treatment with bafilomycin A1 alone also protected glioma cells from cell death. Mechanistically, both compounds significantly reduced cell growth and oxygen consumption. Quantitative proteomics analysis showed that bafilomycin A1 induced broad changes in the cellular proteome. More specifically, proteins downregulated by bafilomycin A1 were associated with the mitochondrial respiratory chain and ATP synthesis. Taken together, our results show that activation of autophagy does not account for the cytoprotective effects of mTOR inhibition in our in vitro model of the glioma microenvironment. Our proteomic findings suggest that the pharmacological inhibition of autophagy induces extensive changes in the cellular proteome that can support glioma cell survival under nutrient-deplete and hypoxic conditions. These findings provide a novel perspective on the complex role of autophagy in gliomas.

Antibody Delivery into the Brain by Radiosensitizer Nanoparticles for Targeted Glioblastoma Therapy

Background

Glioblastoma is the most lethal primary brain malignancy in adults. Standard of care treatment, consisting of temozolomide (TMZ) and adjuvant radiotherapy (RT), mostly does not prevent local recurrence. The inability of drugs to enter the brain, in particular antibody-based drugs and radiosensitizers, is a crucial limitation to effective glioblastoma therapy.

Methods

Here, we developed a combined strategy using radiosensitizer gold nanoparticles coated with insulin to cross the blood-brain barrier and shuttle tumor-targeting antibodies (cetuximab) into the brain.

Results

Following intravenous injection to an orthotopic glioblastoma mouse model, the nanoparticles specifically accumulated within the tumor. Combining targeted nanoparticle injection with TMZ and RT standard of care significantly inhibited tumor growth and extended survival, as compared to standard of care alone. Histological analysis of tumors showed that the combined treatment eradicated tumor cells, and decreased tumor vascularization, proliferation, and repair.

Conclusions

Our findings demonstrate radiosensitizer nanoparticles that effectively deliver antibodies into the brain, target the tumor, and effectively improve standard of care treatment outcome in glioblastoma.

Drivers of Radioresistance in Prostate Cancer

Prostate cancer (PCa) is the second most commonly diagnosed cancer worldwide. Radiotherapy remains one of the first-line treatments in localised disease and may be used as monotherapy or in combination with other treatments such as androgen deprivation therapy or radical prostatectomy. Despite advancements in delivery methods and techniques, radiotherapy has been unable to totally overcome radioresistance resulting in treatment failure or recurrence of previously treated PCa. Various factors have been linked to the development of tumour radioresistance including abnormal tumour vasculature, oxygen depletion, glucose and energy deprivation, changes in gene expression and proteome alterations. Understanding the biological mechanisms behind radioresistance is essential in the development of therapies that are able to produce both initial and sustained response to radiotherapy. This review will investigate the different biological mechanisms utilised by PCa tumours to drive radioresistance.

Interactions of radiation therapy with common and innovative systemic treatments: Antidiabetic treatments, antihypertensives, lipid-lowering medications, immunosuppressive medications and other radiosensitizing methods

The invention and approval of innovative anticancer therapies in the last decade have revolutionized oncology treatment. Radiotherapy is one of the three traditional pillars in oncology treatment with surgery and systemic therapies. Some standard-of-care combinations of chemoradiotherapy widened the therapeutic window of radiation, while some other chemotherapies such as gemcitabine caused unacceptable toxicities when combined with radiation in lung cancers. Fast-paced progress are specially focused on immunotherapies, targeted-therapies, anti-angiogenic treatment, DNA repair inhibitors, hormonotherapy and cell cycle inhibitors. New anticancer therapeutic arsenals provided new possibilities of combined oncological treatments. The interactions of the radiotherapy with other systemic treatments, such as non-anticancer immunomodulatory/immunosuppressive medications are sometimes overlooked even though they could offer a real therapeutic benefit. In this review, we summarize the new opportunities and the risks of historical and novel combined therapies with radiation: non-anticancer immunomodulatory/immunosuppressive drugs, systemic reoxygenation, new therapies such as nanoparticles and SMAC mimetics. Key biological mechanisms, pre-clinical and available clinical data will be provided to demonstrate the promising opportunities in the years to come.

Small Molecules and Immunotherapy Agents for Enhancing Radiotherapy in Glioblastoma

Glioblastoma (GBM) is an aggressive primary brain tumor that is associated with a poor prognosis and quality of life. The standard of care has changed minimally over the past two decades and currently consists of surgery followed by radiotherapy (RT), concomitant and adjuvant temozolomide, and tumor treating fields (TTF). Factors such as tumor hypoxia and the presence of glioma stem cells contribute to the radioresistant nature of GBM. In this review, we discuss the current treatment modalities, mechanisms of radioresistance, and studies that have evaluated promising radiosensitizers. Specifically, we highlight small molecules and immunotherapy agents that have been studied in conjunction with RT in clinical trials. Recent preclinical studies involving GBM radiosensitizers are also discussed.

Small Molecule Inhibitors in Adult High-Grade Glioma: From the Past to the Future

Glioblastoma is the most common primary malignant tumor in the brain and has a dismal prognosis despite patients accepting standard therapies. Alternation of genes and deregulation of proteins, such as receptor tyrosine kinase, PI3K/Akt, PKC, Ras/Raf/MEK, histone deacetylases, poly (ADP-ribose) polymerase (PARP), CDK4/6, branched-chain amino acid transaminase 1 (BCAT1), and Isocitrate dehydrogenase (IDH), play pivotal roles in the pathogenesis and progression of glioma. Simultaneously, the abnormalities change the cellular biological behavior and microenvironment of tumor cells. The differences between tumor cells and normal tissue become the vulnerability of tumor, which can be taken advantage of using targeted therapies. Small molecule inhibitors, as an important part of modern treatment for cancers, have shown significant efficacy in hematologic cancers and some solid tumors. To date, in glioblastoma, there have been more than 200 clinical trials completed or ongoing in which trial designers used small molecules as monotherapy or combination regimens to correct the abnormalities. In this review, we summarize the dysfunctional molecular mechanisms and highlight the outcomes of relevant clinical trials associated with small-molecule targeted therapies. Based on the outcomes, the main findings were that small-molecule inhibitors did not bring more benefit to newly diagnosed glioblastoma, but the clinical studies involving progressive glioblastoma usually claimed “noninferiority” compared with historical results. However, as to the clinical inferiority trial, similar dosing regimens should be avoided in future clinical trials.

Signaling pathways and therapeutic approaches in glioblastoma multiforme (Review)

Glioblastoma multiforme (GBM) is the most aggressive type of primary brain tumor and is associated with a poor clinical prognosis. Despite the progress in the understanding of the molecular and genetic changes that promote tumorigenesis, effective treatment options are limited. The present review intended to identify and summarize major signaling pathways and genetic abnormalities involved in the pathogenesis of GBM, as well as therapies that target these pathways. Glioblastoma remains a difficult to treat tumor; however, in the last two decades, significant improvements in the understanding of GBM biology have enabled advances in available therapeutics. Significant genomic events and signaling pathway disruptions (NF‑κB, Wnt, PI3K/AKT/mTOR) involved in the formation of GBM were discussed. Current therapeutic options may only marginally prolong survival and the current standard of therapy cures only a small fraction of patients. As a result, there is an unmet requirement for further study into the processes of glioblastoma pathogenesis and the discovery of novel therapeutic targets in novel signaling pathways implicated in the evolution of glioblastoma.

Ion Channel Drugs Suppress Cancer Phenotype in NG108-15 and U87 Cells: Toward Novel Electroceuticals for Glioblastoma

Glioblastoma is a lethal brain cancer that commonly recurs after tumor resection and chemotherapy treatment. Depolarized resting membrane potentials and an acidic intertumoral extracellular pH have been associated with a proliferative state and drug resistance, suggesting that forced hyperpolarization and disruption of proton pumps in the plasma membrane could be a successful strategy for targeting glioblastoma overgrowth. We screened 47 compounds and compound combinations, most of which were ion-modulating, at different concentrations in the NG108-15 rodent neuroblastoma/glioma cell line. A subset of these were tested in the U87 human glioblastoma cell line. A FUCCI cell cycle reporter was stably integrated into both cell lines to monitor proliferation and cell cycle response. Immunocytochemistry, electrophysiology, and a panel of physiological dyes reporting voltage, calcium, and pH were used to characterize responses. The most effective treatments on proliferation in U87 cells were combinations of NS1643 and pantoprazole; retigabine and pantoprazole; and pantoprazole or NS1643 with temozolomide. Marker analysis and physiological dye signatures suggest that exposure to bioelectric drugs significantly reduces proliferation, makes the cells senescent, and promotes differentiation. These results, along with the observed low toxicity in human neurons, show the high efficacy of electroceuticals utilizing combinations of repurposed FDA approved drugs.

Radiotherapy as a tool to elicit clinically actionable signalling pathways in cancer

A variety of targeted anticancer agents have been successfully introduced into clinical practice, largely reflecting their ability to inhibit specific molecular alterations that are required for disease progression. However, not all malignant cells rely on such alterations to survive, proliferate, disseminate and/or evade anticancer immunity, implying that many tumours are intrinsically resistant to targeted therapies. Radiotherapy is well known for its ability to activate cytotoxic signalling pathways that ultimately promote the death of cancer cells, as well as numerous cytoprotective mechanisms that are elicited by cellular damage. Importantly, many cytoprotective mechanisms elicited by radiotherapy can be abrogated by targeted anticancer agents, suggesting that radiotherapy could be harnessed to enhance the clinical efficacy of these drugs. In this Review, we discuss preclinical and clinical data that introduce radiotherapy as a tool to elicit or amplify clinically actionable signalling pathways in patients with cancer.

Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline

Purpose

To provide guidance to clinicians regarding therapy for diffuse astrocytic and oligodendroglial tumors in adults.

Methods

ASCO and the Society for Neuro-Oncology convened an Expert Panel and conducted a systematic review of the literature.

Results

Fifty-nine randomized trials focusing on therapeutic management were identified.

Recommendations

Adults with newly diagnosed oligodendroglioma, isocitrate dehydrogenase (IDH)–mutant, 1p19q codeleted CNS WHO grade 2 and 3 should be offered radiation therapy (RT) and procarbazine, lomustine, and vincristine (PCV). Temozolomide (TMZ) is a reasonable alternative for patients who may not tolerate PCV, but no high-level evidence supports upfront TMZ in this setting. People with newly diagnosed astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 2 should be offered RT with adjuvant chemotherapy (TMZ or PCV). People with astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 should be offered RT and adjuvant TMZ. People with astrocytoma, IDH-mutant, CNS WHO grade 4 may follow recommendations for either astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 or glioblastoma, IDH-wildtype, CNS WHO grade 4. Concurrent TMZ and RT should be offered to patients with newly diagnosed glioblastoma, IDH-wildtype, CNS WHO grade 4 followed by 6 months of adjuvant TMZ. Alternating electric field therapy, approved by the US Food and Drug Administration, should be considered for these patients. Bevacizumab is not recommended. In situations in which the benefits of 6-week RT plus TMZ may not outweigh the harms, hypofractionated RT plus TMZ is reasonable. In patients age ≥ 60 to ≥ 70 years, with poor performance status or for whom toxicity or prognosis are concerns, best supportive care alone, RT alone (for MGMTpromoter unmethylated tumors), or TMZ alone (for MGMT promoter methylated tumors) are reasonable treatment options. Additional information is available at www.asco.org/neurooncology-guidelines.

Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline

PURPOSE

To provide guidance to clinicians regarding therapy for diffuse astrocytic and oligodendroglial tumors in adults.

METHODS

ASCO and the Society for Neuro-Oncology convened an Expert Panel and conducted a systematic review of the literature.

RESULTS

Fifty-nine randomized trials focusing on therapeutic management were identified.

RECOMMENDATIONS

Adults with newly diagnosed oligodendroglioma, isocitrate dehydrogenase (IDH)-mutant, 1p19q codeleted CNS WHO grade 2 and 3 should be offered radiation therapy (RT) and procarbazine, lomustine, and vincristine (PCV). Temozolomide (TMZ) is a reasonable alternative for patients who may not tolerate PCV, but no high-level evidence supports upfront TMZ in this setting. People with newly diagnosed astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 2 should be offered RT with adjuvant chemotherapy (TMZ or PCV). People with astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 should be offered RT and adjuvant TMZ. People with astrocytoma, IDH-mutant, CNS WHO grade 4 may follow recommendations for either astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 or glioblastoma, IDH-wildtype, CNS WHO grade 4. Concurrent TMZ and RT should be offered to patients with newly diagnosed glioblastoma, IDH-wildtype, CNS WHO grade 4 followed by 6 months of adjuvant TMZ. Alternating electric field therapy, approved by the US Food and Drug Administration, should be considered for these patients. Bevacizumab is not recommended. In situations in which the benefits of 6-week RT plus TMZ may not outweigh the harms, hypofractionated RT plus TMZ is reasonable. In patients age ≥ 60 to ≥ 70 years, with poor performance status or for whom toxicity or prognosis are concerns, best supportive care alone, RT alone (for MGMT promoter unmethylated tumors), or TMZ alone (for MGMT promoter methylated tumors) are reasonable treatment options. Additional information is available at www.asco.org/neurooncology-guidelines.

Disentangling the signaling pathways of mTOR complexes, mTORC1 and mTORC2, as a therapeutic target in glioblastoma

Aberrant signaling of mechanistic target of rapamycin (mTOR' aka mammalian target of rapamycin) is shown to be linked to tumorigenesis of numerous malignancies including glioblastoma (GB). Glioblastoma mTOR is a serine threonine kinase that functions by forming two multiprotein complexes. There complexes are named mTORC1 and mTORC2 and downstream activated substrate execute cellular and metabolic functions. This signaling cascade of PI3K/AKT/mTOR is often upregulated due to frequent loss of the tumor suppressor PTEN, a phosphatase that functions antagonistically to PI3K. mTOR regulates cell growth, motility, and metabolism by forming two multiprotein complexes, mTORC1 and mTORC2, which are composed of special binding partners. These complexes are sensitive to distinct stimuli. mTORC1 is sensitive to nutrients and mTORC2 is regulated via PI3K and growth factor signaling. Since rapamycin and it's analogue are less effective in treatment of GB, we used novel ATP-competitive dual inhibitors of mTORC1 and mTORC2, namely, Torin1, Torin2, and XL388. Torin2 caused a concentration dependent pharmacodynamic effects on inhibition of phosphorylation of the mTORC1 substrates S6K^Ser235/236 and 4E-BP1^Thr37/46 as well as the mTORC2 substrate AKT^Ser473 resulting in suppression of tumor cell proliferation and migration. Torin1 showed similar effects only at higher doses. Another small molecule compound, XL388 suppressed cell proliferation at a higher dose but failed to inhibit cell migration. Torin1 suppressed phosphorylation of PRAS40^Thr246, however Torin2 completely abolished it. XL388 treatment inhibited the phosphorylation of PRAS40^Thr246 at higher doses only. These findings underscore the use of novel compounds in treatment of cancer. In addition, formulation of third generation mTOR inhibitor "Rapalink-1" may provide new aspects to target mTOR pathways. Numerous inhibitors are currently being used in clinical trials that are aimed to target activated mTOR pathways.

A Functional Precision Medicine Pipeline Combines Comparative Transcriptomics and Tumor Organoid Modeling to Identify Bespoke Treatment Strategies for Glioblastoma

Li Fraumeni syndrome (LFS) is a hereditary cancer predisposition syndrome caused by germline mutations in TP53. TP53 is the most common mutated gene in human cancer, occurring in 30-50% of glioblastomas (GBM). Here, we highlight a precision medicine platform to identify potential targets for a GBM patient with LFS. We used a comparative transcriptomics approach to identify genes that are uniquely overexpressed in the LFS GBM patient relative to a cancer compendium of 12,747 tumor RNA sequencing data sets, including 200 GBMs. STAT1 and STAT2 were identified as being significantly overexpressed in the LFS patient, indicating ruxolitinib, a Janus kinase 1 and 2 inhibitors, as a potential therapy. The LFS patient had the highest level of STAT1 and STAT2 expression in an institutional high-grade glioma cohort of 45 patients, further supporting the cancer compendium results. To empirically validate the comparative transcriptomics pipeline, we used a combination of adherent and organoid cell culture techniques, including ex vivo patient-derived organoids (PDOs) from four patient-derived cell lines, including the LFS patient. STAT1 and STAT2 expression levels in the four patient-derived cells correlated with levels identified in the respective parent tumors. In both adherent and organoid cultures, cells from the LFS patient were among the most sensitive to ruxolitinib compared to patient-derived cells with lower STAT1 and STAT2 expression levels. A spheroid-based drug screening assay (3D-PREDICT) was performed and used to identify further therapeutic targets. Two targeted therapies were selected for the patient of interest and resulted in radiographic disease stability. This manuscript supports the use of comparative transcriptomics to identify personalized therapeutic targets in a functional precision medicine platform for malignant brain tumors.

Therapeutic strtegies of glioblastoma (GBM): The current advances in the molecular targets and bioactive small molecule compounds

Glioblastoma (GBM) is the most common aggressive malignant tumor in brain neuroepithelial tumors and remains incurable. A variety of treatment options are currently being explored to improve patient survival, including small molecule inhibitors, viral therapies, cancer vaccines, and monoclonal antibodies. Among them, the unique advantages of small molecule inhibitors have made them a focus of attention in the drug discovery of glioblastoma. Currently, the most used chemotherapeutic agents are small molecule inhibitors that target key dysregulated signaling pathways in glioblastoma, including receptor tyrosine kinase, PI3K/AKT/mTOR pathway, DNA damage response, TP53 and cell cycle inhibitors. This review analyzes the therapeutic benefit and clinical development of novel small molecule inhibitors discovered as promising anti-glioblastoma agents by the related targets of these major pathways. Meanwhile, the recent advances in temozolomide resistance and drug combination are also reviewed. In the last part, due to the constant clinical failure of targeted therapies, this paper reviewed the research progress of other therapeutic methods for glioblastoma, to provide patients and readers with a more comprehensive understanding of the treatment landscape of glioblastoma.

The Bumpy Road towards mTOR Inhibition in Glioblastoma: Quo Vadis?

Glioblastoma multiforme (GBM), a grade IV astrocytoma, is a lethal brain tumor with a poor prognosis. Despite recent advances in the molecular biology of GBM, neuro-oncologists have very limited treatment options available to improve the survival of GBM patients. A prominent signaling pathway implicated in GBM pathogenesis is that of the mechanistic target of rapamycin (mTOR). Attempts to target the mTOR pathway with first-generation mTOR inhibitors appeared promising in the preclinical stage; however, results have been disappointing in clinical trials, owing to the heterogeneous nature of GBM, escape mechanisms against treatment, the blood–brain barrier, drug-related toxicities, and the imperfect design of clinical trials, among others. The development of next-generation mTOR inhibitors and their current evaluation in clinical trials have sparked new hope to realize the clinical potential of mTOR inhibitors in GBM. Meanwhile, studies are continuously furthering our understanding of mTOR signaling dysregulation, its downstream effects, and interplay with other signaling pathways in GBM tumors. Therefore, it remains to be seen whether targeting mTOR in GBM will eventually prove to be fruitful or futile.

Clinical and Preclinical Outcomes of Combining Targeted Therapy With Radiotherapy

In the era of precision medicine, radiation medicine is currently focused on the precise delivery of highly conformal radiation treatments. However, the tremendous developments in targeted therapy are yet to fulfill their full promise and arguably have the potential to dramatically enhance the radiation therapeutic ratio. The increased ability to molecularly profile tumors both at diagnosis and at relapse and the co-incident progress in the field of radiogenomics could potentially pave the way for a more personalized approach to radiation treatment in contrast to the current ‘‘one size fits all’’ paradigm. Few clinical trials to date have shown an improved clinical outcome when combining targeted agents with radiation therapy, however, most have failed to show benefit, which is arguably due to limited preclinical data. Several key molecular pathways could theoretically enhance therapeutic effect of radiation when rationally targeted either by directly enhancing tumor cell kill or indirectly through the abscopal effect of radiation when combined with novel immunotherapies. The timing of combining molecular targeted therapy with radiation is also important to determine and could greatly affect the outcome depending on which pathway is being inhibited.

Toll-like receptors and toll-like receptor-targeted immunotherapy against glioma

Glioma represents a fast proliferating and highly invasive brain tumor which is resistant to current therapies and invariably recurs. Despite some advancements in anti-glioma therapies, patients’ prognosis remains poor. Toll-like receptors (TLRs) act as the first line of defense in the immune system being the detectors of those associated with bacteria, viruses, and danger signals. In the glioma microenvironment, TLRs are expressed on both immune and tumor cells, playing dual roles eliciting antitumoral (innate and adaptive immunity) and protumoral (cell proliferation, migration, invasion, and glioma stem cell maintenance) responses. Up to date, several TLR-targeting therapies have been developed aiming at glioma bulk and stem cells, infiltrating immune cells, the immune checkpoint axis, among others. While some TLR agonists exhibited survival benefit in clinical trials, it attracts more attention when they are involved in combinatorial treatment with radiation, chemotherapy, immune vaccination, and immune checkpoint inhibition in glioma treatment. TLR agonists can be used as immune modulators to enhance the efficacy of other treatment, to avoid dose accumulation, and what brings more interests is that they can potentiate immune checkpoint delayed resistance to PD-1/PD-L1 blockade by upregulating PD-1/PD-L1 overexpression, thus unleash powerful antitumor responses when combined with immune checkpoint inhibitors. Herein, we focus on recent developments and clinical trials exploring TLR-based treatment to provide a picture of the relationship between TLR and glioma and their implications for immunotherapy.

Translation Initiation Machinery as a Tumor Selective Target for Radiosensitization

Towards improving the efficacy of radiotherapy, one approach is to target the molecules and processes mediating cellular radioresponse. Along these lines, translational control of gene expression has been established as a fundamental component of cellular radioresponse, which suggests that the molecules participating in this process (i.e., the translational machinery) can serve as determinants of radiosensitivity. Moreover, the proteins comprising the translational machinery are often overexpressed in tumor cells suggesting the potential for tumor specific radiosensitization. Studies to date have shown that inhibiting proteins involved in translation initiation, the rate-limiting step in translation, specifically the three members of the eIF4F cap binding complex eIF4E, eIF4G, and eIF4A as well as the cap binding regulatory kinases mTOR and Mnk1/2, results in the radiosensitization of tumor cells. Because ribosomes are required for translation initiation, inhibiting ribosome biogenesis also appears to be a strategy for radiosensitization. In general, the radiosensitization induced by targeting the translation initiation machinery involves inhibition of DNA repair, which appears to be the consequence of a reduced expression of proteins critical to radioresponse. The availability of clinically relevant inhibitors of this component of the translational machinery suggests opportunities to extend this approach to radiosensitization to patient care.

Glioblastoma multiforme (GBM): An overview of current therapies and mechanisms of resistance

Glioblastoma multiforme (GBM) is a WHO grade IV glioma and the most common malignant, primary brain tumor with a 5-year survival of 7.2%. Its highly infiltrative nature, genetic heterogeneity, and protection by the blood brain barrier (BBB) have posed great treatment challenges. The standard treatment for GBMs is surgical resection followed by chemoradiotherapy. The robust DNA repair and self-renewing capabilities of glioblastoma cells and glioma initiating cells (GICs), respectively, promote resistance against all current treatment modalities. Thus, durable GBM management will require the invention of innovative treatment strategies. In this review, we will describe biological and molecular targets for GBM therapy, the current status of pharmacologic therapy, prominent mechanisms of resistance, and new treatment approaches. To date, medical imaging is primarily used to determine the location, size and macroscopic morphology of GBM before, during, and after therapy. In the future, molecular and cellular imaging approaches will more dynamically monitor the expression of molecular targets and/or immune responses in the tumor, thereby enabling more immediate adaptation of tumor-tailored, targeted therapies.

The PI3K/AKT/mTOR signaling pathway inhibitors enhance radiosensitivity in cancer cell lines

INTRODUCTION

Radiotherapy is one of the most common types of cancer treatment modalities. Radiation can affect both cancer and normal tissues, which limits the whole delivered dose. It is well documented that radiation activates phosphatidylinositol 3-kinase (PI3K) and AKT signaling pathway; hence, the inhibition of this pathway enhances the radiosensitivity of tumor cells. The mammalian target of rapamycin (mTOR) is a regulator that is involved in autophagy, cell growth, proliferation, and survival.

CONCLUSION

The inhibition of mTOR as a downstream mediator of the PI3K/AKT signaling pathway represents a vital option for more effective cancer treatments. The combination of PI3K/AKT/mTOR inhibitors with radiation can increase the radiosensitivity of malignant cells to radiation by autophagy activation. Therefore, this review aims to discuss the impact of such inhibitors on the cell response to radiation.

The Current State of Potential Therapeutic Modalities for Glioblastoma Multiforme: A Clinical Review

Glioblastoma multiforme (GBM), as the most lethal brain tumor, continues to be incurable. Considering the high mortality rate of GBM, it is crucial to develop new treatment approaches. Conventional therapies, including maximal surgical resection, radiation therapy, and chemotherapy (typically temozolomide), have not led to significant changes in the survival rates of GBM patients. However, emerging modalities, such as the use of tyrosine kinase inhibitors, mTOR inhibitors, NF-κB modulators, nitrosoureas, and immunotherapeutic agents have shown promising in improving GBM outcomes. In this context, we reviewed the current status of GBM treatment, the efficacy of existing standard therapies in improving disease outcomes, and future therapeutic directions.

Molecularly targeted treatment of recurrent anaplastic astrocytoma - a case report

High-grade astrocytomas are malignant and aggressive, with limited treatment options. Treatment is geared not only toward increasing patient's overall survival but also in delaying or preventing neurological disability, a cause of significant morbidity. Increasingly, targeted and customized treatment approaches, especially for recurrent disease, are being explored. Here we present a successful outcome in a young patient with rapidly progressive disease who responded to targeted treatment based on genetic sequencing and circulating tumor DNA markers, given the inaccessibility of the tissue to biopsy. Molecular testing on tissue, serum or CSF may be helpful in identifying unique targets in these complex patients.

Progress and prospect in tumor treating fields treatment of glioblastoma

Glioblastoma (GBM) is a challenging cancer with poor prognosis. The classical standard for treatment is safe resection, followed by concurrent chemoradiotherapy with subsequent adjuvant temozolomide (TMZ). Despite several attempts at different treatments, the 5-year survival rate remains poor. In recent years, with the continuous progress of treatment technology, tumor treating fields (TTFields) were preferable. The device could generate an intermediate frequency alternating electric field and induce apoptosis of some specific types of cancer cells with few toxic and side effects. TTFields induced apoptosis through multiple activations of the pathway. TTFields have been Food and Drug Administration (FDA)-approved for diagnosis and recurrent GBM as additional clinical trial results are revealed. This study reviewed the current status, mechanisms, correlations with immune pathways, the prospects of applying TTFields for GBM, and the adverse events.

A Comparison Between Chemo-Radiotherapy Combined With Immunotherapy and Chemo-Radiotherapy Alone for the Treatment of Newly Diagnosed Glioblastoma: A Systematic Review and Meta-Analysis

Background

Immunotherapy for GBM is an emerging field which is increasingly being investigated in combination with standard of care treatment options with variable reported success rates.

Objective

To perform a systematic review of the available data to evaluate the safety and efficacy of combining immunotherapy with standard of care chemo-radiotherapy following surgical resection for the treatment of newly diagnosed GBM.

Methods

A literature search was performed for published clinical trials evaluating immunotherapy for GBM from January 1, 2000, to October 1, 2020, in PubMed and Cochrane using PICOS/PRISMA/MOOSE guidelines. Only clinical trials with two arms (combined therapy vs. control therapy) were included. Outcomes were then pooled using weighted random effects model for meta-analysis and compared using the Wald-type test. Primary outcomes included 1-year overall survival (OS) and progression-free survival (PFS), secondary outcomes included severe adverse events (SAE) grade 3 or higher.

Results

Nine randomized phase II and/or III clinical trials were included in the analysis, totaling 1,239 patients. The meta-analysis revealed no statistically significant differences in group’s 1-year OS [80.6% (95% CI: 68.6%–90.2%) vs. 72.6% (95% CI: 65.7%–78.9%), p = 0.15] or in 1-year PFS [37% (95% CI: 26.4%–48.2%) vs. 30.4% (95% CI: 25.4%–35.6%) p = 0.17] when the immunotherapy in combination with the standard of care group (combined therapy) was compared to the standard of care group alone (control). Severe adverse events grade 3 to 5 were more common in the immunotherapy and standard of care group than in the standard of care group (47.3%, 95% CI: 20.8–74.6%, vs 43.8%, 95% CI: 8.7–83.1, p = 0.81), but this effect also failed to reach statistical significance.

Conclusion

Our results suggests that immunotherapy can be safely combined with standard of care chemo-radiotherapy without significant increase in grade 3 to 5 SAE; however, there is no statistically significant increase in overall survival or progression free survival with the combination therapy.

Targeting RTK-PI3K-mTOR Axis in Gliomas: An Update

Gliomas are the most common and challenging malignancies of the central nervous system (CNS), due to their infiltrative nature, tendency to recurrence, and poor response to treatments. Indeed, despite the advances in neurosurgical techniques and in radiation therapy, the modest effects of therapy are still challenging. Moreover, tumor recurrence is associated with the onset of therapy resistance; it is therefore critical to identify effective and well-tolerated pharmacological approaches capable of inducing durable responses in the appropriate patient groups. Molecular alterations of the RTK/PI3K/Akt/mTOR signaling pathway are typical hallmarks of glioma, and several clinical trials targeting one or more players of this axis have been launched, showing disappointing results so far, due to the scarce BBB permeability of certain compounds or to the occurrence of resistance/tolerance mechanisms. However, as RTK/PI3K/mTOR is one of the pivotal pathways regulating cell growth and survival in cancer biology, targeting still remains a strong rationale for developing strategies against gliomas. Future rigorous clinical studies, aimed at addressing the tumor heterogeneity, the interaction with the microenvironment, as well as diverse posology adjustments, are needed-which might unravel the therapeutic efficacy and response prediction of an RTK/PI3K/mTOR-based approach.

A Systematic Review of Glioblastoma-Targeted Therapies in Phases II, III, IV Clinical Trials

Glioblastoma (GBM), the most frequent and aggressive glial tumor, is currently treated as first line by the Stupp protocol, which combines, after surgery, radiotherapy and chemotherapy. For recurrent GBM, in absence of standard treatment or available clinical trials, various protocols including cytotoxic drugs and/or bevacizumab are currently applied. Despite these heavy treatments, the mean overall survival of patients is under 18 months. Many clinical studies are underway. Based on clinicaltrials.org and conducted up to 1 April 2020, this review lists, not only main, but all targeted therapies in phases II-IV of 257 clinical trials on adults with newly diagnosed or recurrent GBMs for the last twenty years. It does not involve targeted immunotherapies and therapies targeting tumor cell metabolism, that are well documented in other reviews. Without surprise, the most frequently reported drugs are those targeting (i) EGFR (40 clinical trials), and more generally tyrosine kinase receptors (85 clinical trials) and (ii) VEGF/VEGFR (75 clinical trials of which 53 involving bevacizumab). But many other targets and drugs are of interest. They are all listed and thoroughly described, on an one-on-one basis, in four sections related to targeting (i) GBM stem cells and stem cell pathways, (ii) the growth autonomy and migration, (iii) the cell cycle and the escape to cell death, (iv) and angiogenesis.

Rapid Progressive Glioblastoma despite Radiation in a Patient with Myelodysplastic Syndrome

The rapidity of glioblastoma progression can be exacerbated by impaired systemic immune surveillance. We describe an elderly woman with advanced 5q– myelodysplastic syndrome (MDS) associated with trilineage dysfunction in hematopoiesis. She also developed multiple solid tumor malignancies including ER/PR-positive and HER2-negative breast cancer, probable lung cancer without histologic confirmation, and primary glioblastoma with a high proliferation index of 80%. Because of low platelet counts of 20,000–30,000/µL that required periodic transfusion and a reduced white cell count of 600–900/µL, she was deemed unsafe to take concomitant daily temozolomide during radiation and her glioblastoma was treated with a shortened course of radiotherapy alone. Her baseline absolute neutrophil count was 110–390/µL, and CD4⁺ and CD8⁺ lymphocyte counts were 235/µL and 113/µL, respectively. During the last week of radiation, the patient developed a nonfluent aphasia, increased fatigue, and aspiration pneumonia. A gadolinium-enhanced head MRI, obtained 2 days after completion of radiation and 39 days after biopsy, demonstrated near tripling of the size of the left frontal tumor with a significant amount of adjacent cerebral edema. This case raises the possibility that advanced MDS is a negative immunomodulatory condition that can accelerate glioblastoma progression.

Rapamycin-Loaded Lipid Nanocapsules Induce Selective Inhibition of the mTORC1-Signaling Pathway in Glioblastoma Cells

Inhibition of the PI3K/Akt/mTOR signaling pathway represents a potential issue for the treatment of cancer, including glioblastoma. As such, rapamycin that inhibits the mechanistic target of rapamycin (mTOR), the downstream effector of this signaling pathway, is of great interest. However, clinical development of rapamycin has floundered due to the lack of a suitable formulation of delivery systems. In the present study, a novel method for the formulation of safe rapamycin nanocarriers is investigated. A phase inversion process was adapted to prepare lipid nanocapsules (LNCs) loaded with the lipophilic and temperature sensitive rapamycin. Rapamycin-loaded LNCs (LNC-rapa) are ~110 nm in diameter with a low polydispersity index (<0.05) and the zeta potential of about −5 mV. The encapsulation efficiency, determined by spectrophotometry conjugated with filtration/exclusion, was found to be about 69%, which represents 0.6 wt% of loading capacity. Western blot analysis showed that LNC-rapa do not act synergistically with X-ray beam radiation in U87MG glioblastoma model in vitro. Nevertheless, it demonstrated the selective inhibition of the phosphorylation of mTORC1 signaling pathway on Ser2448 at a concentration of 1 μM rapamycin in serum-free medium. Interestingly, cells cultivated in normoxia (21% O₂) seem to be more sensitive to mTOR inhibition by rapamycin than those cultivated in hypoxia (0.4% O₂). Finally, we also established that mTOR phosphorylation inhibition by LNC-rapa induced a negative feedback through the activation of Akt phosphorylation. This phenomenon was more noticeable after stabilization of HIF-1α in hypoxia.