A phase II study of bevacizumab and erlotinib after radiation and temozolomide in MGMT unmethylated GBM patients

Clinical Predictors of Overall Survival in Very Elderly Patients With Glioblastoma: A National Cancer Database Multivariable Analysis

BACKGROUND AND OBJECTIVES

Surgery for the very elderly is a progressively important paradigm as life expectancy continues to rise. Patients with glioblastoma multiforme often undergo surgery, radiotherapy (RT), and chemotherapy (CT) to prolong overall survival (OS). However, the efficacy of these treatment modalities in patients aged 80 years and older has yet to be fully assessed in the literature.

METHODS

The National Cancer Database was used to retrospectively identify patients aged 65 years and older with glioblastoma multiforme (1989-2016). All available patient demographic characteristics, disease characteristics, and clinical outcomes were collected. To study OS, bivariable survival models were created using Kaplan-Meier estimates. A Cox proportional-hazards model was used for final adjusted analyses.

RESULTS

A total of 578 very elderly patients (aged 80 years and older) and 2836 elderly patients (aged 65-79 years) were identified. Compared with elderly patients, very elderly patients were more likely to have Medicare (odds ratio [OR] 1.899 [95% CI: 1.417-2.544], P < .001) while less likely to have private insurance status (OR 0.544 [95% CI: 0.401-0.739], P < .001). In addition, very elderly patients were more likely to travel the least distance for treatment and have multiple tumors (P < .001). When controlling for demographic and disease characteristics, very elderly patients were less likely to receive gross total resection (GTR) (OR 0.822 [95% CI: 0.681-0.991], P < .041), RT (OR 0.385 [95% CI: 0.319-0.466], P < .001), or postoperative CT (OR 0.298 [95% CI: 0.219-0.359], P < .001) relative to elderly counterparts. Within very elderly patients, GTR, RT, and CT all independently and significantly predicted improved OS (P < .001 for all). These predictive models were deployed in an online calculator (https://spine.shinyapps.io/GBM_elderly).

CONCLUSION

Very elderly patients are less likely to receive GTR, RT, or CT when compared with elderly counterparts despite use of these therapies conferring improved OS. Selected very elderly patients may benefit from more aggressive attempts at surgical and adjuvant treatment.

Emerging Therapies for Glioblastoma

Glioblastoma is most commonly a primary brain tumor and the utmost malignant one, with a survival rate of approximately 12-18 months. Glioblastoma is highly heterogeneous, demonstrating that different types of cells from the same tumor can manifest distinct gene expression patterns and biological behaviors. Conventional therapies such as temozolomide, radiation, and surgery have limitations. As of now, there is no cure for glioblastoma. Alternative treatment methods to eradicate glioblastoma are discussed in this review, including targeted therapies to PI3K, NFKβ, JAK-STAT, CK2, WNT, NOTCH, Hedgehog, and TGFβ pathways. The highly novel application of oncolytic viruses and nanomaterials in combating glioblastoma are also discussed. Despite scores of clinical trials for glioblastoma, the prognosis remains poor. Progress in breaching the blood-brain barrier with nanomaterials and novel avenues for targeted and combination treatments hold promise for the future development of efficacious glioblastoma therapies.

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.

Epidermal Growth Factor Receptor Inhibitors in Glioblastoma: Current Status and Future Possibilities

Glioblastoma, a grade 4 glioma as per the World Health Organization, poses a challenge in adult primary brain tumor management despite advanced surgical techniques and multimodal therapies. This review delves into the potential of targeting epidermal growth factor receptor (EGFR) with small-molecule inhibitors and antibodies as a treatment strategy. EGFR, a mutationally active receptor tyrosine kinase in over 50% of glioblastoma cases, features variants like EGFRvIII, EGFRvII and missense mutations, necessitating a deep understanding of their structures and signaling pathways. Although EGFR inhibitors have demonstrated efficacy in other cancers, their application in glioblastoma is hindered by blood-brain barrier penetration and intrinsic resistance. The evolving realm of nanodrugs and convection-enhanced delivery offers promise in ensuring precise drug delivery to the brain. Critical to success is the identification of glioblastoma patient populations that benefit from EGFR inhibitors. Tools like radiolabeled anti-EGFR antibody 806i facilitate the visualization of EGFR conformations, aiding in tailored treatment selection. Recognizing the synergistic potential of combination therapies with downstream targets like mTOR, PI3k, and HDACs is pivotal for enhancing EGFR inhibitor efficacy. In conclusion, the era of precision oncology holds promise for targeting EGFR in glioblastoma, contingent on tailored treatments, effective blood-brain barrier navigation, and the exploration of synergistic therapies.

Efficacy and safety of chlorpromazine as an adjuvant therapy for glioblastoma in patients with unmethylated MGMT gene promoter: RACTAC, a phase II multicenter trial

Introduction

Drug repurposing is a promising strategy to develop new treatments for glioblastoma. In this phase II clinical trial, we evaluated the addition of chlorpromazine to temozolomide in the adjuvant phase of the standard first-line therapeutic protocol in patients with unmethylated MGMT gene promoter.

Methods

This was a multicenter phase II single-arm clinical trial. The experimental procedure involved the combination of CPZ with standard treatment with TMZ in the adjuvant phase of the Stupp protocol in newly-diagnosed GBM patients carrying an unmethylated MGMT gene promoter. Progression-free survival was the primary endpoint. Secondary endpoints were overall survival and toxicity.

Results

Forty-one patients were evaluated. Twenty patients (48.7%) completed 6 cycles of treatment with TMZ+CPZ. At 6 months, 27 patients (65.8%) were without progression, achieving the primary endpoint. Median PFS was 8.0 months (95% CI: 7.0-9.0). Median OS was 15.0 months (95% CI: 13.1-16.9). Adverse events led to reduction or interruption of CPZ dosage in 4 patients (9.7%).

Discussion

The addition of CPZ to standard TMZ in the first-line treatment of GBM patients with unmethylated MGMT gene promoter was safe and led to a longer PFS than expected in this population of patients. These findings provide proof-of-concept for the potential of adding CPZ to standard TMZ treatment in GBM patients with unmethylated MGMT gene promoter.

Clinical trial registration

https://clinicaltrials.gov/study/NCT04224441, identifier NCT04224441.

CHCHD2 mediates glioblastoma cell proliferation, mitochondrial metabolism, hypoxia‑induced invasion and therapeutic resistance

Glioblastoma (GBM) is the most common and malignant primary brain tumor affecting adults and remains incurable. The mitochondrial coiled‑coil‑helix‑coiled‑coil‑helix domain‑containing protein 2 (CHCHD2) has been demonstrated to mediate mitochondrial respiration, nuclear gene expression and cell migration; however, evidence of this in GBM is lacking. In the present study, it was hypothesized that CHCHD2 may play a functional role in U87 GBM cells expressing the constitutively active epidermal growth factor receptor variant III (EGFRvIII). The amplification of the CHCHD2 gene was found to be associated with a decreased patient overall and progression‑free survival. The CHCHD2 mRNA levels were increased in high‑vs. low‑grade glioma, IDH‑wt GBMs, and in tumor vs. non‑tumor tissue. Additionally, CHCHD2 protein expression was greatest in invasive, EGFRvIII‑expressing patient‑derived samples. The CRISPR‑Cas9‑mediated knockout of CHCHD2 in EGFRvIII‑expressing U87 cells resulted in an altered mitochondrial respiration and glutathione status, in decreased cell growth and invasion under both normoxic and hypoxic conditions, and in an enhanced sensitivity to cytotoxic agents. CHCHD2 was distributed in both the mitochondria and nuclei of U87 and U87vIII cells, and the U87vIII cells exhibited a greater nuclear expression of CHCHD2 compared to isogenic U87 cells. Incubation under hypoxic conditions, serum starvation and the reductive unfolding of CHCHD2 induced the nuclear accumulation of CHCHD2 in both cell lines. Collectively, the findings of the present study indicate that CHCHD2 mediates a variety of GBM characteristics, and highlights mitonuclear retrograde signaling as a pathway of interest in GBM cell biology.

Improving the efficacy of anti-EGFR drugs in GBM: Where we are going?

The therapies targeting mutations of driver genes in cancer have advanced into clinical trials for a variety of tumors. In glioblastoma (GBM), epidermal growth factor receptor (EGFR) is the most commonly mutated oncogene, and targeting EGFR has been widely investigated as a promising direction. However, the results of EGFR pathway inhibitors have not been satisfactory. Limited blood-brain barrier (BBB) permeability, drug resistance, and pathway compensation mechanisms contribute to the failure of anti-EGFR therapies. This review summarizes recent research advances in EGFR-targeted therapy for GBM and provides insight into the reasons for the unsatisfactory results of EGFR-targeted therapy. By combining the results of preclinical studies with those of clinical trials, we discuss that improved drug penetration across the BBB, the use of multi-target combinations, and the development of peptidomimetic drugs under the premise of precision medicine may be promising strategies to overcome drug resistance in GBM.

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.

Telomerase inhibition is an effective therapeutic strategy in TERT promoter-mutant glioblastoma models with low tumor volume

BACKGROUND

Glioblastoma is one of the most lethal forms of cancer, with 5-year survival rates of only 6%. Glioblastoma-targeted therapeutics have been challenging to develop due to significant inter- and intra-tumoral heterogeneity. Telomerase reverse transcriptase gene (TERT) promoter mutations are the most common known clonal oncogenic mutations in glioblastoma. Telomerase is therefore considered to be a promising therapeutic target against this tumor. However, an important limitation of this strategy is that cell death does not occur immediately after telomerase ablation, but rather after several cell divisions required to reach critically short telomeres. We, therefore, hypothesize that telomerase inhibition would only be effective in glioblastomas with low tumor burden.

METHODS

We used CRISPR interference to knock down TERT expression in TERT promoter-mutant glioblastoma cell lines and patient-derived models. We then measured viability using serial proliferation assays. We also assessed for features of telomere crisis by measuring telomere length and chromatin bridge formation. Finally, we used a doxycycline-inducible CRISPR interference system to knock down TERT expression in vivo early and late in tumor development.

RESULTS

Upon TERT inactivation, glioblastoma cells lose their proliferative ability over time and exhibit telomere shortening and chromatin bridge formation. In vivo, survival is only prolonged when TERT knockdown is induced shortly after tumor implantation, but not when the tumor burden is high.

CONCLUSIONS

Our results support the idea that telomerase inhibition would be most effective at treating glioblastomas with low tumor burden, for example in the adjuvant setting after surgical debulking and chemoradiation.

Antiangiogenic Therapy for Malignant Brain Tumors: Does It Still Matter?

PURPOSE OF REVIEW

To summarize the mechanisms of tumor angiogenesis and resistance to antiangiogenic therapy, and the influence on tumor microenvironment.

RECENT FINDINGS

Several clinical trials have investigated the activity of anti-VEGF monoclonal antibodies and tyrosine kinase inhibitors in glioblastoma, shedding the light on their limitations in terms of disease control and survival. We have outlined the mechanisms of resistance to antiangiogenic therapy, including vessel co-option, hypoxic signaling in response to vessel destruction, modulation of glioma stem cells, and trafficking of tumor-associated macrophages in tumor microenvironment. Moreover, novel generation of antiangiogenic compounds for glioblastoma, including small interfering RNAs and nanoparticles, as a delivery vehicle, could enhance selectivity and reduce side effects of treatments. There is still a rationale for the use of antiangiogenic therapy, but a better understanding of vascular co-option, vascular mimicry, and dynamic relationships between immunosuppressive microenvironment and blood vessel destruction is crucial to develop next-generation antiangiogenic compounds.

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.

Luteolin enhances erlotinib’s cell proliferation inhibitory and apoptotic effects in glioblastoma cell lines

The epidermal growth factor (EGFR) receptor is frequently overexpressed in glioblastoma multiforme IV (GBM). Increased expression of EGFR leads to increased proliferation, decreased apoptosis, and increased resistance to chemotherapeutic agents. A small molecule called erlotinib inhibits EGFR receptors by binding to their adenosine triphosphate (ATP) binding sites. It is FDA approved to treat a variety of EGFR-mediated cancers. Several clinical trials have explored a combination of erlotinib with other agents to treat glioblastoma since it is believed that erlotinib would benefit patients with GBM with EGFR mutations or expression. Luteolin, a natural flavonoid, inhibits cell growth and induces apoptosis in cancer cells. We investigated the combined effects of erlotinib and luteolin on proliferation and apoptosis on glioblastoma cell lines overexpressing EGFR or glioma cells expressing truncated EGFR (ΔEGFR). In a concentration-dependent fashion, the combination of luteolin and erlotinib reduced cell proliferation (p < 0.05) and induced apoptosis by cleaving PARP and increasing caspase expression. In addition, the combination of luteolin and erlotinib reduced the phosphorylation of downstream EGFR cell signaling molecules such as Akt, NF kappa B, and STAT3 in a concentration-dependent manner. These findings suggest that combining luteolin with erlotinib offers a potential treatment strategy for glioblastoma multiforme IV.

Current and promising treatment strategies in glioma

Gliomas are the most common primary central nervous system tumors; despite recent advances in diagnosis and treatment, glioma patients generally have a poor prognosis. Hence there is a clear need for improved therapeutic options. In recent years, significant effort has been made to investigate immunotherapy and precision oncology approaches. The review covers well-established strategies such as surgery, temozolomide, PCV, and mTOR inhibitors. Furthermore, it summarizes promising therapies: tumor treating fields, immune therapies, tyrosine kinases inhibitors, IDH(Isocitrate dehydrogenase)-targeted approaches, and others. While there are many promising treatment strategies, none fundamentally changed the management of glioma patients. However, we are still awaiting the outcome of ongoing trials, which have the potential to revolutionize the treatment of glioma.

Phase I/II trial of local interstitial chemotherapy with arsenic trioxide in patients with newly diagnosed glioma

Background

Glioma is the most common primary brain tumor in adults with poor prognosis. The glioma patients benefit from STUPP strategy, including maximum and safe resection and adjuvant radiotherapy and chemotherapy. Arsenic trioxide could inhibit various tumors. However, it is a challenge to evaluate the efficiency and safety of srsenic trioxide in glioma patients.

Objective

The arsenic trioxide has the potent therapeutic effect on glioma. However, the safety and efficacy of local interstitial chemotherapy with arsenic trioxide in newly diagnosed glioma patients is unclear.

Methods

All patients received partial or complete tumor resection and intraoperative implantation of Ommaya reservoirs followed by standard radiotherapy. Arsenic trioxide with the starting dose 0.3 mg was administered via an Ommaya reservoir catheter inserted into the tumor cavity for 5 consecutive days every 3 months for a total of eight cycles unless tumor progression or excessive toxicity was observed.

Results

No hematological or grade 4 non-hematological toxicity was observed in any patient during arsenic trioxide treatment. The maximum tolerated dose of 1.5 mg of arsenic trioxide was safe and well tolerated. The median overall survival for WHO grade 3 glioma was 33.6 months, and for glioblastoma was 13.9 months. The median progression-free survival for WHO grade 2 glioma was 40.3 months, for grade 3 glioma was 21.5 months, and for glioblastoma was 9.5 months.

Conclusion

These results suggest that arsenic trioxide is safe and well tolerated with local delivery into the tumor cavity of the brain, and the dose recommended for a phase II trial is 1.5 mg.

Multifunctional Magnetic Nanoparticles for MRI-guided Co-delivery of Erlotinib and L-Asparaginase to Ovarian Cancer

AIM(S)

The use of magnetic nanoparticles (MNPs) in biomedical applications has been wildly opted due to their unique properties. The objective of this study was to evaluate the effects of aptamer-armed MNPs in ovarian cancer treatment and as T2 weighted MRI contrast agent.

METHODS

Here, we designed MNPs loaded with erlotinib (ERL/SPION-Val-PEG) and conjugated them with anti-mucin16 (MUC16) aptamer to introduce new image-guided nanoparticles (NPs) for targeted drug delivery as well as non-invasive magnetic resonance imaging (MRI) contrast agents. Also, the combination of our nanosystem (NS) along with L-Asparaginase (L-ASPN) led to synergistic effects in terms of reducing cell viability in ovarian cancer cells, which could suggest a novel combination therapy.

RESULTS

The mean size of our NS was about 63.4 ± 3.4 nm evaluated by DLS analysis and its morphology was confirmed using TEM. Moreover, the functional groups, as well as magnetic properties of our NS, were examined by FT-IR and VSM tests, respectively. The loading efficacy of erlotinib on MNPs was about 80% and its release reached 70.85% over 7 days in the pH value of 5.4. The MR images and flow cytometry results revealed that the cellular uptake of ERL/SPION-Val-PEG-MUC16 NPs in cells with MUC16 overexpression was considerably higher than unarmed NPs. In addition, T2-weight MR images of ovarian cancer-bearing mice indicated significant signal intensity changes at the tumor site 4 h after intravenous injection compared to the non-target MNPs.

CONCLUSIONS

Our data suggest ERL/SPION-Val-PEG NPs as an image-guided co-drug delivery system for ovarian cancer.

Targeting Glioblastoma Stem Cells to Overcome Chemoresistance: An Overview of Current Therapeutic Strategies

Glioblastoma (GBM) is the most malignant primary brain tumor. The current standard approach in GBM is surgery, followed by treatment with radiation and temozolomide (TMZ); however, GBM is highly resistant to current therapies, and the standard of care has not been revised over the last two decades, indicating an unmet need for new therapies. GBM stem cells (GSCs) are a major cause of chemoresistance due to their ability to confer heterogeneity and tumorigenic capacity. To improve patient outcomes and survival, it is necessary to understand the properties and mechanisms underlying GSC chemoresistance. In this review, we describe the current knowledge on various resistance mechanisms of GBM to therapeutic agents, with a special focus on TMZ, and summarize the recent findings on the intrinsic and extrinsic mechanisms of chemoresistance in GSCs. We also discuss novel therapeutic strategies, including molecular targeting, autophagy inhibition, oncolytic viral therapy, drug repositioning, and targeting of GSC niches, to eliminate GSCs, from basic research findings to ongoing clinical trials. Although the development of effective therapies for GBM is still challenging, this review provides a better understanding of GSCs and offers future directions for successful GBM therapy.

Tumor-associated alterations in white matter connectivity have prognostic significance in MGMT-unmethylated glioblastoma

PURPOSE

We investigated the prognostic significance of tumor-associated white matter (TA-WM) tracts in glioblastoma (GBM) using magnetic resonance-diffusion tensor imaging (MR-DTI). We hypothesized that (1) TA-WM tracts harbor microscopic disease not targeted through surgery or radiotherapy (RT), and (2) the greater the extent of TA-WM involvement, the worse the survival outcomes.

METHODS

We studied a retrospective cohort of 76 GBM patients. TA-WM tracts were identified by MR-DTI fractional anisotropy (FA) maps. For each patient, 22 TA-WM tracts were analyzed and each tract was graded 1-3 based on FA. A TA-WM score (TA-WMS) was computed based on number of involved tracts and corresponding FA grade of involvement. Kaplan-Meier statistics were utilized to determine survival outcomes, log-rank test was used to compare survival between groups, and Cox regression was utilized to determine prognostic variables.

RESULTS

For the MGMT-unmethylated cohort, there was a decrease in OS for increasing TA-WMS (median OS 16.5 months for TA-WMS 0-4; 13.6 months for TA-WMS 5-8; 7.3 months for TA-WMS > 9; p = 0.0002). This trend was not observed in the MGMT-methylated cohort. For MGMT-unmethylated patients with TA-WMS > 6 and involvement of tracts passing through brainstem or contralateral hemisphere, median OS was 8.3 months versus median OS 14.1 months with TA-WMS > 6 but not involving aforementioned critical tracts (p = 0.003 log-rank test). For MGMT-unmethylated patients, TA-WMS was predictive of overall survival in multivariate analysis (HR = 1.14, 95% CI 1.03-1.27, p = 0.012) while age, gender, and largest tumor dimension were non-significant.

CONCLUSION

Increased TA-WMS and involvement of critical tracts are associated with decreased overall survival in MGMT-unmethylated GBM.

High myosin binding protein H expression predicts poor prognosis in glioma patients

Glioma is the most common and fatal primary brain tumor in humans. Myosin binding protein H (MYBPH), which was first identified as an important myofibrillar constituent of vertebrate skeletal and cardiac muscles, reduces cell motility and metastasis. However, its role in gliomas remains unclear. We evaluated the expression of MYBPH in glioma using Gene Expression Profiling Interactive Analysis ( http://gepia.cancer-pku.cn/ ) and Chinese Glioma Genome Atlas ( https://www.cgga.org.cn/ ). The results showed that MYBPH was highly expressed in glioma tissues. Moreover, MYBPH expression was significantly associated with high tumor aggressiveness and poor outcomes in glioma patients. Mechanistically, the results suggested that MYBPH might promote tumor progression by improving tumor invasion and migration. Our results establish MYBPH as an important prognostic biomarker that could be considered a potential epigenetic and immunotherapeutic target for treatment. We showed that MYBPH is a novel biomarker that is variably expressed in glioblastoma (GBM). The association of high MYBPH expression with poor prognosis in newly diagnosed GBM patients and increased expression in recurrent GBM is indicative of its role in tumor aggressiveness.

Clinical strategies to manage adult glioblastoma patients without MGMT hypermethylation

Glioblastoma (GBM) is a highly malignant brain tumor with a dismal prognosis. Standard therapy for GBM comprises surgical resection, followed by radiotherapy plus concomitant and adjuvant temozolomide (TMZ) therapy. The methylation status of the O6-methylguanine DNA methyltransferase (MGMT) promoter is one of the most essential predictive biomarkers for patients with GBM treated with TMZ. Patients with an unmethylated MGMT promoter (umMGMT), who comprise 60% of patients with GBM, present an even worse prognosis because of TMZ resistance. Radiotherapy with various fractionation, chemotherapy compensating for TMZ, targeted therapy against diverse oncogenic pathways, immunotherapy of vaccine or immune checkpoint inhibitor, and tumor treating fields have been studied in umMGMT GBM patients. However, most efforts have yielded negative results or merely minimal improvements. Therefore, effective patient subgroup selection concerning precision medicine has become the focus. By assigning different treatments to the corresponding patient subgroups, a better curative effect and subsequently prolonged survival can be achieved. In this review, we re-evaluate the value of standard TMZ therapy and summarize the new clinical strategies and attempts to treat patients with umMGMT, which yielded positive and negative results, to provide alternative treatment options and discuss future directions of umMGMT GBM treatment.

Glioblastoma pharmacotherapy: A multifaceted perspective of conventional and emerging treatments (Review)

Due to its localisation, rapid onset, high relapse rate and resistance to most currently available treatment methods, glioblastoma multiforme (GBM) is considered to be the deadliest type of all gliomas. Although surgical resection, chemotherapy and radiotherapy are among the therapeutic strategies used for the treatment of GBM, the survival rates achieved are not satisfactory, and there is an urgent need for novel effective therapeutic options. In addition to single-target therapy, multi-target therapies are currently under development. Furthermore, drugs are being optimised to improve their ability to cross the blood-brain barrier. In the present review, the main strategies applied for GBM treatment in terms of the most recent therapeutic agents and approaches that are currently under pre-clinical and clinical testing were discussed. In addition, the most recently reported experimental data following the testing of novel therapies, including stem cell therapy, immunotherapy, gene therapy, genomic correction and precision medicine, were reviewed, and their advantages and drawbacks were also summarised.

The immune landscape of common CNS malignancies: implications for immunotherapy

Immunotherapy has enabled remarkable therapeutic responses across cancers of various lineages, albeit with some notable exceptions such as glioblastoma. Several previous misconceptions, which have impaired progress in the past, including the presence and role of the blood-brain barrier and a lack of lymphatic drainage, have been refuted. Nonetheless, a subset of patients with brain metastases but, paradoxically, not the vast majority of those with gliomas are able to respond to immune-checkpoint inhibitors. Immune profiling of samples obtained from patients with central nervous system malignancies using techniques such as mass cytometry and single-cell sequencing along with experimental data from genetically engineered mouse models have revealed fundamental differences in immune composition and immunobiology that not only explain the differences in responsiveness to these agents but also lay the foundations for immunotherapeutic strategies that are applicable to gliomas. Herein, we review the emerging data on the differences in immune cell composition, function and interactions within central nervous system tumours and provide guidance on the development of novel immunotherapies for these historically difficult-to-treat cancers.

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.

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.

The Normal and Brain Tumor Vasculature: Morphological and Functional Characteristics and Therapeutic Targeting

Glioblastoma is among the most common tumor of the central nervous system in adults. Overall survival has not significantly improved over the last decade, even with optimizing standard therapeutic care including extent of resection and radio- and chemotherapy. In this article, we review features of the brain vasculature found in healthy cerebral tissue and in glioblastoma. Brain vessels are of various sizes and composed of several vascular cell types. Non-vascular cells such as astrocytes or microglia also interact with the vasculature and play important roles. We also discuss in vitro engineered artificial blood vessels which may represent useful models for better understanding the tumor-vessel interaction. Finally, we summarize results from clinical trials with anti-angiogenic therapy alone or in combination, and discuss the value of these approaches for targeting glioblastoma.

NVP-BEZ235 or JAKi Treatment leads to decreased survival of examined GBM and BBC cells

Cancer cells almost universally harbor constitutively active Phosphatidylinositol-3 Kinase (PI3K) Pathway activity via mutation of key signaling components and/or epigenetic mechanisms. Scores of PI3K Pathway inhibitors are currently under investigation as putative chemotherapeutics. However, feedback and stem cell mechanisms induced by PI3K Pathway inhibition can lead to reduced treatment efficacy. To address therapeutic barriers, we examined whether JAKi would reduce stem gene expression in a setting of PI3K Pathway inhibition in order to improve treatment efficacy. We targeted the PI3K Pathway with NVP-BEZ235 (dual PI3K and mTOR inhibitor) in combination with the Janus Kinase inhibitor JAKi in glioblastoma (GBM) and basal-like breast cancer (BBC) cell lines. We examined growth, gene expression, and apoptosis in cells treated with NVP-BEZ235 and/or JAKi. Growth and recovery assays showed no significant impact of dual treatment with NVP-BEZ235/JAKi compared to NVP-BEZ235 treatment alone. Gene expression and flow cytometry revealed that single and dual treatments induced apoptosis. Stem gene expression was retained in dual NVP-BEZ235/JAKi treatment samples. Future in vivo studies may give further insight into the impact of combined NVP-BEZ235/JAKi treatment in GBM and BBC.

Impact of depatuxizumab mafodotin on health-related quality of life and neurological functioning in the phase II EORTC 1410/INTELLANCE 2 trial for EGFR-amplified recurrent glioblastoma

BACKGROUND

In the EORTC 1410/INTELLANCE 2 randomised, phase II study (NCT02343406), with the antibody-drug conjugate depatuxizumab mafodotin (Depatux-M, ABT-414) in patients with recurrent EGFR-amplified glioblastoma, the primary end-point (overall survival) was not met, and the drug had ocular dose-limiting toxicity. This study reports results from the prespecified health-related quality of life (HRQoL) and neurological deterioration-free survival (NDFS) exploratory analysis.

PATIENTS AND METHODS

Patients (n = 260) were randomised 1:1:1 to receive either Depatux-M 1.25 mg/kg or 1.0 mg/kg intravenously every 2 weeks with oral temozolomide (TMZ) 150 mg/m², Depatux-M alone, or TMZ or oral lomustine (CCNU) 110 mg/m² (TMZ/CCNU). HRQoL outcomes were recorded using the EORTC core Quality of Life QLQ-C30, and brain cancer-specific QLQ-BN20 questionnaires. Questionnaires were completed at baseline, weeks 8 and 16, and month 6, and changes from baseline to each time point were calculated. NDFS was defined as time to first deterioration in World Health Organisation performance status.

RESULTS

Compliance with HRQoL was 88.1% at baseline and decreased to 37.9% at month 6. Differences from baseline between Depatux-M arms and TMZ/CCNU in global health/QoL status throughout treatment did not reach clinical relevance (≥10 points). Self-reported visual disorders deteriorated to a clinically relevant extent with Depatux-M arms versus TMZ/CCNU at all timepoints (mean differences range: 24.6-35.1 points). Changes from baseline for other HRQoL scales and NDFS were generally similar between treatment arms.

CONCLUSIONS

Depatux-M had no impact on HRQoL and NDFS in patients with EGFR-amplified recurrent glioblastoma, except for more visual disorders, an expected side-effect of the study drug.

CLINICAL TRIAL REGISTRATION

NCT02343406.

Outcomes and Patterns of Care in Elderly Patients with Glioblastoma Multiforme

BACKGROUND

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults, with an increased incidence among the elderly. However, the optimal treatment strategy in elderly patients remains unclear. This study seeks to investigate the effect of patient selection and treatment strategies on survival trends in these patients.

METHODS

Patients with diagnosis codes specific for GBM were queried from the National Cancer Database during 2004-2016. Univariate and multivariate Cox regression analysis was performed to investigate outcomes. Survival curves and 5-year survival were also generated based on patient-specific factors.

RESULTS

Among 104,456 patients with GBM identified, elderly patients were less likely to receive radiotherapy (61.3% vs. 77.8%; P < 0.001) or chemotherapy (47.2% vs. 62.9%; P < 0.001) or to undergo surgical resection (68.3% vs. 81.8; P < 0.001). Mean overall survival was 9.1 months (standard deviation, 10.0) and 5-year survival was 5.3%. Multivariate analysis showed age 75-84 years (hazard ratio [HR], 1.39; 95% confidence interval [CI], 1.12-1.73; P = 0.003) and lower Karnofsky Performance Status (50-70: HR, 1.68, 95% CI, 1.35-2.08, P < 0.001; ≤40: HR, 1.79, 95% CI 1.18-2.72, P = 0.006) were associated with decreased overall survival, whereas surgical resection (subtotal resection: HR, 0.52, 95% CI, 0.38-0.71, P < 0.001; gross total resection: HR, 0.29, 95% CI, 0.21-0.41, P < 0.001), radiotherapy (HR, 0.65; 95% CI, 0.47-0.91; P = 0.012), and chemotherapy (HR, 0.65; 95% CI, 0.48-0.88; P = 0.006) were associated with increased overall survival in elderly patients.

CONCLUSIONS

In an analysis of 104,456 patients with GBM, all treatment modalities were found to be used less frequently in elderly patients. Increasing age and poor performance status were associated with worsened survival. Gross total resection was associated with the greatest survival benefit, and chemotherapy and radiotherapy also improved survival outcomes. These treatment options improved outcomes regardless of performance status. Although maximal treatment strategies may improve survival in elderly patients with GBM, these treatment strategies must be balanced against patient-specific factors and quality-of-life concerns.

Updated Insights on EGFR Signaling Pathways in Glioma

Nowadays, due to recent advances in molecular biology, the pathogenesis of glioblastoma is better understood. For the newly diagnosed, the current standard of care is represented by resection followed by radiotherapy and temozolomide administration, but because median overall survival remains poor, new diagnosis and treatment strategies are needed. Due to the quick progression, even with aggressive multimodal treatment, glioblastoma remains almost incurable. It is known that epidermal growth factor receptor (EGFR) amplification is a characteristic of the classical subtype of glioma. However, targeted therapies against this type of receptor have not yet shown a clear clinical benefit. Many factors contribute to resistance, such as ineffective blood-brain barrier penetration, heterogeneity, mutations, as well as compensatory signaling pathways. A better understanding of the EGFR signaling network, and its interrelations with other pathways, are essential to clarify the mechanisms of resistance and create better therapeutic agents.

The medical necessity of advanced molecular testing in the diagnosis and treatment of brain tumor patients

Accurate pathologic diagnoses and molecularly informed treatment decisions for a wide variety of cancers depend on robust clinical molecular testing that uses genomic, epigenomic, and transcriptomic-based tools. Nowhere is this more essential than in the workup of brain tumors, as emphasized by the incorporation of molecular criteria into the 2016 World Health Organization classification of central nervous system tumors and the updated official guidelines of the National Comprehensive Cancer Network. Despite the medical necessity of molecular testing in brain tumors, access to and utilization of molecular diagnostics is still highly variable across institutions, and a lack of reimbursement for such testing remains a significant obstacle. The objectives of this review are (i) to identify barriers to adoption of molecular testing in brain tumors, (ii) to describe the current molecular tools recommended for the clinical evaluation of brain tumors, and (iii) to summarize how molecular data are interpreted to guide clinical care, so as to improve understanding and justification for their coverage in the routine workup of adult and pediatric brain tumor cases.

Autophagy as a Potential Therapy for Malignant Glioma

Glioma is the most frequent and aggressive type of brain neoplasm, being anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM), its most malignant forms. The survival rate in patients with these neoplasms is 15 months after diagnosis, despite a diversity of treatments, including surgery, radiation, chemotherapy, and immunotherapy. The resistance of GBM to various therapies is due to a highly mutated genome; these genetic changes induce a de-regulation of several signaling pathways and result in higher cell proliferation rates, angiogenesis, invasion, and a marked resistance to apoptosis; this latter trait is a hallmark of highly invasive tumor cells, such as glioma cells. Due to a defective apoptosis in gliomas, induced autophagic death can be an alternative to remove tumor cells. Paradoxically, however, autophagy in cancer can promote either a cell death or survival. Modulating the autophagic pathway as a death mechanism for cancer cells has prompted the use of both inhibitors and autophagy inducers. The autophagic process, either as a cancer suppressing or inducing mechanism in high-grade gliomas is discussed in this review, along with therapeutic approaches to inhibit or induce autophagy in pre-clinical and clinical studies, aiming to increase the efficiency of conventional treatments to remove glioma neoplastic cells.

DNA repair genes in astrocytoma tumorigenesis, progression and therapy resistance

Glioblastoma (GBM) is the most common and malignant type of primary brain tumor, showing rapid development and resistance to therapies. On average, patients survive 14.6 months after diagnosis and less than 5% survive five years or more. Several pieces of evidence have suggested that the DNA damage signaling and repair activities are directly correlated with GBM phenotype and exhibit opposite functions in cancer establishment and progression. The functions of these pathways appear to present a dual role in tumorigenesis and cancer progression. Activation and/or overexpression of ATRX, ATM and RAD51 genes were extensively characterized as barriers for GBM initiation, but paradoxically the exacerbated activity of these genes was further associated with cancer progression to more aggressive stages. Excessive amounts of other DNA repair proteins, namely HJURP, EXO1, NEIL3, BRCA2, and BRIP, have also been connected to proliferative competence, resistance and poor prognosis. This scenario suggests that these networks help tumor cells to manage replicative stress and treatment-induced damage, diminishing genome instability and conferring therapy resistance. Finally, in this review we address promising new drugs and therapeutic approaches with potential to improve patient survival. However, despite all technological advances, the prognosis is still dismal and further research is needed to dissect such complex mechanisms.

Myosin IIA suppresses glioblastoma development in a mechanically sensitive manner

The ability of glioblastoma to disperse through the brain contributes to its lethality, and blocking this behavior has been an appealing therapeutic approach. Although a number of proinvasive signaling pathways are active in glioblastoma, many are redundant, so targeting one can be overcome by activating another. However, these pathways converge on nonredundant components of the cytoskeleton, and we have shown that inhibiting one of these-the myosin II family of cytoskeletal motors-blocks glioblastoma invasion even with simultaneous activation of multiple upstream promigratory pathways. Myosin IIA and IIB are the most prevalent isoforms of myosin II in glioblastoma, and we now show that codeleting these myosins markedly impairs tumorigenesis and significantly prolongs survival in a rodent model of this disease. However, while targeting just myosin IIA also impairs tumor invasion, it surprisingly increases tumor proliferation in a manner that depends on environmental mechanics. On soft surfaces myosin IIA deletion enhances ERK1/2 activity, while on stiff surfaces it enhances the activity of NFκB, not only in glioblastoma but in triple-negative breast carcinoma and normal keratinocytes as well. We conclude myosin IIA suppresses tumorigenesis in at least two ways that are modulated by the mechanics of the tumor and its stroma. Our results also suggest that inhibiting tumor invasion can enhance tumor proliferation and that effective therapy requires targeting cellular components that drive both proliferation and invasion simultaneously.

Safety and efficacy of depatuxizumab mafodotin + temozolomide in patients with EGFR-amplified, recurrent glioblastoma: results from an international phase I multicenter trial

Background

Patients with glioblastoma (GBM) have a dismal prognosis. Nearly all will relapse with no clear standard of care for recurrent disease (rGBM). Approximately 50% of patients have tumors harboring epidermal growth factor receptor (EGFR) amplification. The antibody-drug conjugate depatuxizumab mafodotin (depatux-m) binds cells with EGFR amplification, is internalized, and releases a microtubule toxin, killing the cell. Here we report efficacy, safety and pharmacokinetics (PK) of depatux-m + temozolomide (TMZ) in patients with EGFR-amplified rGBM.

Methods

M12-356 (NCT01800695) was an open-label study encompassing patients with newly diagnosed or rGBM across 3 treatment arms. Results are reported for adults with EGFR-amplified, measurable rGBM who received depatux-m (0.5-1.5 mg/kg) on days 1 and 15, and TMZ (150-200 mg/m2) on days 1-5 in a 28-day cycle. Patients were bevacizumab and nitrosourea naïve.

Results

There were 60 patients, median age 56 years (range, 20-79). Fifty-nine patients previously received TMZ. Common adverse events (AEs) were blurred vision (63%), fatigue (38%), and photophobia (35%). Grades 3/4 AEs were split between ocular and non-ocular AEs, occurring in 22% of patients each. Systemic PK exposure of depatux-m was dose proportional. The objective response rate was 14.3%, the 6-month progression-free survival rate was 25.2%, and the 6-month overall survival rate was 69.1%.

Conclusions

Depatux-m + TMZ displayed an AE profile similar to what was described previously. Antitumor activity in this TMZ-refractory population was encouraging. Continued study of depatux-m in patients with EGFR-amplified, newly diagnosed, or recurrent GBM is ongoing in 2 global, randomized trials (NCT02573324, NCT02343406).

EGF/EGFR upregulates and cooperates with Netrin-4 to protect glioblastoma cells from DNA damage-induced senescence

BACKGROUND

Glioblastoma multiforme (GBM) is the most malignant central nervous system tumor. Alkylating agent, temozolomide (TMZ), is currently the first-line chemotherapeutic agent for GBM. However, the sensitivity of GBM cells to TMZ is affected by many factors. And, several clinic trials, including co-administration of TMZ with other drugs, have failed in successful treatment of GBM. We have previously reported that Netrin-4 (NTN4), a laminin-like axon guidance protein, plays a protective role in GBM cell senescence upon TMZ-triggered DNA damage. However, the master regulator of NTN4 needs further elucidation. Epidermal growth factor/Epidermal growth factor receptor (EGF/EGFR) can modulate the expression of various extracellular matrix related molecules, and prevent DNA damage in GBM cells. In this study, we investigated the relationship between EGF/EGFR signaling and NTN4, and explored their effect on therapeutic efficacy in GBM cells upon TMZ treatment.

METHODS

Co-expression analysis were performed by using the RNA sequencing data from NIH 934 cell lines and from single cell RNA sequencing data of GBM tumor. The co-expressing genes were used for GO enrichment and signaling pathway enrichment. mRNA expression of the target genes were quantified by qPCR, and cell senescence were investigated by Senescence-Associated Beta-Galactosidase Staining. Protein phosphorylation were observed and analyzed by immunoblotting. The RNA sequencing data and clinical information of TMZ treated patients were extracted from TCGA-glioblastoma project, and then used for Kaplan-Meier survival analysis.

RESULTS

Analysis of RNA sequencing data revealed a potential co-expression relationship between NTN4 and EGFR. GO enrichment of EGFR-correlated genes indicated that EGFR regulates GBM cells in a manner similar to that in central nervous system development and neural cell differentiation. Pathway analysis suggested that EGFR and its related genes contribute to cell adhesion, extracellular matrix (ECM) organization and caspase related signaling. We also show that EGF stimulates NTN4 expression in GBM cells and cooperates with NTN4 to attenuate GBM cell senescence induced by DNA damage, possibly via AKT and ERK. Clinical analysis showed that co-expression of EGFR and NTN4 significantly predicts poor survival in TMZ-treated GBM patients.

CONCLUSIONS

This study indicates that EGF/EGFR regulates and cooperates with NTN4 in DNA damage resistance in GBM. Therefore, our findings provide a potential therapeutic target for GBM.

Autophagic and Apoptotic Pathways as Targets for Chemotherapy in Glioblastoma

Glioblastoma multiforme is the most malignant and aggressive type of brain tumor, with a mean life expectancy of less than 15 months. This is due in part to the high resistance to apoptosis and moderate resistant to autophagic cell death in glioblastoma cells, and to the poor therapeutic response to conventional therapies. Autophagic cell death represents an alternative mechanism to overcome the resistance of glioblastoma to pro-apoptosis-related therapies. Nevertheless, apoptosis induction plays a major conceptual role in several experimental studies to develop novel therapies against brain tumors. In this review, we outline the different components of the apoptotic and autophagic pathways and explore the mechanisms of resistance to these cell death pathways in glioblastoma cells. Finally, we discuss drugs with clinical and preclinical use that interfere with the mechanisms of survival, proliferation, angiogenesis, migration, invasion, and cell death of malignant cells, favoring the induction of apoptosis and autophagy, or the inhibition of the latter leading to cell death, as well as their therapeutic potential in glioma, and examine new perspectives in this promising research field.

Integrated mapping of pharmacokinetics and pharmacodynamics in a patient-derived xenograft model of glioblastoma

Therapeutic options for the treatment of glioblastoma remain inadequate despite concerted research efforts in drug development. Therapeutic failure can result from poor permeability of the blood-brain barrier, heterogeneous drug distribution, and development of resistance. Elucidation of relationships among such parameters could enable the development of predictive models of drug response in patients and inform drug development. Complementary analyses were applied to a glioblastoma patient-derived xenograft model in order to quantitatively map distribution and resulting cellular response to the EGFR inhibitor erlotinib. Mass spectrometry images of erlotinib were registered to histology and magnetic resonance images in order to correlate drug distribution with tumor characteristics. Phosphoproteomics and immunohistochemistry were used to assess protein signaling in response to drug, and integrated with transcriptional response using mRNA sequencing. This comprehensive dataset provides simultaneous insight into pharmacokinetics and pharmacodynamics and indicates that erlotinib delivery to intracranial tumors is insufficient to inhibit EGFR tyrosine kinase signaling.

Human Glioma Migration and Infiltration Properties as a Target for Personalized Radiation Medicine

Gliomas are primary brain tumors that present the majority of malignant adult brain tumors. Gliomas are subdivided into low- and high-grade tumors. Despite extensive research in recent years, the prognosis of malignant glioma patients remains poor. This is caused by naturally highly infiltrative capacities as well as high levels of radio- and chemoresistance. Additionally, it was shown that low linear energy transfer (LET) irradiation enhances migration and invasion of several glioma entities which might counteract today’s treatment concepts. However, this finding is discussed controversially. In the era of personalized medicine, this controversial data might be attributed to the patient-specific heterogeneity that ultimately could be used for treatment. Thus, current developments in glioma therapy should be seen in the context of intrinsic and radiation-enhanced migration and invasion. Due to the natural heterogeneity of glioma cells and different radiation responses, a personalized radiation treatment concept is suggested and alternative radiation concepts are discussed.

A biobank of patient-derived pediatric brain tumor models

Brain tumors are the leading cause of cancer-related death in children. Genomic studies have provided insights into molecular subgroups and oncogenic drivers of pediatric brain tumors that may lead to novel therapeutic strategies. To evaluate new treatments, better preclinical models adequately reflecting the biological heterogeneity are needed. Through the Children's Oncology Group ACNS02B3 study, we have generated and comprehensively characterized 30 patient-derived orthotopic xenograft models and seven cell lines representing 14 molecular subgroups of pediatric brain tumors. Patient-derived orthotopic xenograft models were found to be representative of the human tumors they were derived from in terms of histology, immunohistochemistry, gene expression, DNA methylation, copy number, and mutational profiles. In vivo drug sensitivity of targeted therapeutics was associated with distinct molecular tumor subgroups and specific genetic alterations. These models and their molecular characterization provide an unprecedented resource for the cancer community to study key oncogenic drivers and to evaluate novel treatment strategies.

Overview on current treatment standards in high-grade gliomas

High-grade gliomas (HGGs) are the most common primary tumors of the central nervous system, which include anaplastic gliomas (grade III) and glioblastomas (GBM, grade IV). Surgery is the mainstay of treatment in HGGs in order to achieve a histological and molecular characterization, as well as relieve neurological symptoms and improve seizure control. Combinations of some molecular factors, such as IDH 1-2 mutations, 1p/19q codeletion and MGMT methylation status, allow to classify different subtypes of gliomas and identify patients with different outcome. The SOC in HGGs consists in a combination of radiotherapy and chemotherapy with alkylating agents. Despite this therapeutic approach, tumor recurrence occurs in HGGs, and new surgical debulking, reirradiation or second-line chemotherapy are needed. Considering the poor results in terms of survival, several clinical trials have explored the efficacy and tolerability of antiangiogenic agents, targeted therapies against epidermal growth factor receptor (EGFR) and different immunotherapeutic approaches in recurrent and newly-diagnosed GBM, including immune checkpoint inhibitors (ICIs), and cell- or peptide-based vaccination with unsatisfactory results in term of disease control. In this review we describe the major updates in molecular biology of HGGs according to 2016 WHO Classification, the current management in newly-diagnosed and recurrent GBM and grade III gliomas, and the results of the most relevant clinical trials on targeted agents and immunotherapy.

Evolutionary basis of a new gene- and immune-therapeutic approach for the treatment of malignant brain tumors: from mice to clinical trials for glioma patients

Glioma cells are one of the most aggressive and malignant tumors. Following initial surgery, and radio-chemotherapy they progress rapidly, so that patients' median survival remains under two years. They invade throughout the brain, which makes them difficult to treat, and are universally lethal. Though total resection is always attempted it is not curative. Standard of care in 2016 comprises surgical resection, radiotherapy and chemotherapy (temozolomide). Median survival is currently ~14-20months post-diagnosis though it can be higher in high complexity medical university centers, or during clinical trials. Why the immune system fails to recognize the growing brain tumor is not completely understood. We believe that one reason for this failure is that the brain lacks cells that perform the role that dendritic cells serve in other organs. The lack of functional dendritic cells from the brain causes the brain to be deficient in priming systemic immune responses to glioma antigens. To overcome this drawback we reconstituted the brain immune system for it to initiate and prime anti-glioma immune responses from within the brain. To achieve brain immune reconstitution adenoviral vectors are injected into the resection cavity or remaining tumor. One adenoviral vector expresses the HSV-1 derived thymidine kinase which converts ganciclovir into phospho-ganciclovir which becomes cytotoxic to dividing cells. The second adenovirus expresses the cytokine fms-like tyrosine kinase 3 ligand (Flt3L). Flt3L differentiates precursors into dendritic cells and acts as a chemokine for dendritic cells. This results in HSV-1/ganciclovir killing of tumor cells, and the release of tumor antigens, which are then taken up by dendritic cells recruited to the brain tumor microenvironment by Flt3L. Concomitant release of HMGB1, a TLR2 agonist that activates dendritic cells, stimulates dendritic cells loaded with glioma antigens to migrate to the cervical lymph nodes to prime a systemic CD8+ T cytotoxic killing of brain tumor cells. This induced immune response causes glioma-specific cytotoxicity, induces immunological memory, and does not cause brain toxicity or autoimmunity. A Phase I Clinical Trial, to test our hypothesis in human patients, was opened in December 2013 (see: NCT01811992, Combined Cytotoxic and Immune-Stimulatory Therapy for Glioma, at ClinicalTrials.gov). This trial is a first in human trial to test whether the re-engineering of the brain immune system can serve to treat malignant brain tumors. The long and winding road from the laboratory to the clinical trial follows below.

Efficacy of depatuxizumab mafodotin (ABT-414) monotherapy in patients with EGFR-amplified, recurrent glioblastoma: results from a multi-center, international study

PURPOSE

Patients with recurrent glioblastoma (rGBM) have a poor prognosis. Epidermal growth factor receptor (EGFR) gene amplification is present in ~ 50% of glioblastomas (GBMs). Depatuxizumab mafodotin (depatux-m), formerly ABT-414, is an antibody-drug conjugate that preferentially binds cells with EGFR amplification, is internalized and releases a potent antimicrotubule agent, monomethyl auristatin F (MMAF). Here we report the safety, pharmacokinetics, and efficacy of depatux-m monotherapy at the recommended Phase 2 dose (RPTD) in patients with EGFR-amplified, rGBM.

METHODS

M12-356 (NCT01800695) is an open-label study with three escalation and expansion cohorts. Sixty-six patients with EGFR-amplified, rGBM were treated with depatux-m monotherapy at 1.25 mg/kg intravenously every 2 weeks. Adults with measurable rGBM, who were bevacizumab-naïve, with EGFR amplification were eligible.

RESULTS

Among 66 patients, median age was 58 years (range 35-80). All patients were previously treated with radiotherapy/temozolomide. The most common adverse events (AEs) were eye related (91%), including blurred vision (65%), dry eye (29%), keratitis, and photophobia (27% each). Grade 3/4 AEs occurred in 42% of all patients, and ocular Grade 3/4 AEs occurred in 33% of patients overall. One patient (2%) had a Grade 4 ocular AE. Ocular AEs were manageable and usually resolved once treatment with depatux-m ceased. The objective response rate was 6.8%, the 6-month progression-free survival rate was 28.8%, and the 6-month overall survival rate was 72.5%.

CONCLUSION

Depatux-m monotherapy displayed frequent but mostly Grade 1/2 ocular toxicities. A PFS6 of 28.8% was observed in this rGBM population, warranting further study.

Genomic alterations of ERBB receptors in cancer: clinical implications

The ERBB family of receptor tyrosine kinases has been implicated in carcinogenesis for over three decades with rigorous attention to EGFR and HER2. ERBB receptors, consisting of EGFR, HER2, HER3, and HER4 are part of a complicated signaling network that activates downstream signaling pathways including PI3K/AKT, Ras/Raf/MAPK, JAK/STAT and PKC. It is well established that EGFR is amplified and/or mutated in gliomas and non-small-cell lung carcinoma while HER2 is amplified and/or over-expressed in breast, gastric, ovarian, non-small cell lung carcinoma, and several other tumor types. With the advent of next generation sequencing and large scale efforts to explore the entire spectrum of genomic alterations involved in human cancer progression, it is now appreciated that somatic ERBB receptor mutations occur at relatively low frequencies across multiple tumor types. Some of these mutations may represent oncogenic driver events; clinical studies are underway to determine whether tumors harboring these alterations respond to small molecule EGFR/HER2 inhibitors. Recent evidence suggests that some somatic ERBB receptor mutations render resistance to FDA-approved EGFR and HER2 inhibitors. In this review, we focus on the landscape of genomic alterations of EGFR, HER2, HER3 and HER4 in cancer and the clinical implications for patients harboring these alterations.

Human fibulin-3 protein variant expresses anti-cancer effects in the malignant glioma extracellular compartment in intracranial xenograft models

Background

Decades of cytotoxic and more recently immunotherapy treatments for malignant glioma have had limited success due to dynamic intra-tumoral heterogeneity. The dynamic interplay of cancer cell subpopulations has been found to be under the control of proteins in the cancer microenvironment. EGF-containing fibulin-like extracellular matrix protein (EFEMP1) (also fibulin-3) has the multiple functions of suppressing cancer growth and angiogenesis, while promoting cancer cell invasion. EFEMP1-derived tumor suppressor protein (ETSP) retains EFEMP1’s anti-growth and anti-angiogenic functions while actually inhibiting cancer cell invasion.

Methods

In this study, we examined the therapeutic effect on glioblastoma multiforme (GBM) of an in vitro synthesized protein, ZR30, which is based on the sequence of ETSP, excluding the signaling peptide.

Results

ZR30 showed the same effects as ETSP in blocking EGFR/NOTCH/AKT signaling pathways, when applied to cultures of multiple GBM cell lines and primary cultures. ZR30’s inhibition of MMP2 activation was shown not only for GBM cells, but also for other types of cancer cells having overexpression of MMP2. A significant improvement in survival of mice with orthotopic human GBM xenografts was observed after a single, intra-tumoral injection of ZR30. Using a model mimicking the intra-tumoral heterogeneity of GBM with cell subpopulations carrying different invasive and proliferative phenotypes, we demonstrated an equal and simultaneous tumor suppressive effect of ZR30 on both tumor cell subpopulations, with suppression of FOXM1 and activation of SEMA3B expressions in the xenografts.

Conclusion

Overall, the data support a complementary pleiotrophic therapeutic effect of ZR30 acting in the extracellular compartment of GBM.

Resolving the phylogenetic origin of glioblastoma via multifocal genomic analysis of pre-treatment and treatment-resistant autopsy specimens

Glioblastomas are malignant neoplasms composed of diverse cell populations. This intratumoral diversity has an underlying architecture, with a hierarchical relationship through clonal evolution from a common ancestor. Therapies are limited by emergence of resistant subclones from this phylogenetic reservoir. To characterize this clonal ancestral origin of recurrent tumors, we determined phylogenetic relationships using whole exome sequencing of pre-treatment IDH1/2 wild-type glioblastoma specimens, matched to post-treatment autopsy samples (n = 9) and metastatic extracranial post-treatment autopsy samples (n = 3). We identified “truncal” genetic events common to the evolutionary ancestry of the initial specimen and later recurrences, thereby inferring the identity of the precursor cell population. Mutations were identified in a subset of cases in known glioblastoma genes such as NF1(n = 3), TP53(n = 4) and EGFR(n = 5). However, by phylogenetic analysis, there were no protein-coding mutations as recurrent truncal events across the majority of cases. In contrast, whole copy-loss of chromosome 10 (12 of 12 cases), copy-loss of chromosome 9p21 (11 of 12 cases) and copy-gain in chromosome 7 (10 of 12 cases) were identified as shared events in the majority of cases. Strikingly, mutations in the TERT promoter were also identified as shared events in all evaluated pairs (9 of 9). Thus, we define four truncal non-coding genomic alterations that represent early genomic events in gliomagenesis, that identify the persistent cellular reservoir from which glioblastoma recurrences emerge. Therapies to target these key early genomic events are needed. These findings offer an evolutionary explanation for why precision therapies that target protein-coding mutations lack efficacy in GBM.

Non-coding and structural alterations may be early drivers of brain cancer development. A team led by Priscilla Brastianos and Tracy Batchelor from Massachusetts General Hospital, Boston, USA, analyzed the genetic landscape of glioblastoma by comparing pre-treatment and autopsy tumor specimens from 12 patients who died of the aggressive brain cancer. They identified a common set of four genetic events that occurred early in the evolution of nearly every patient’s cancer: three losses or gains of chromosome regions or entire chromosomes, and mutations in the gene-activating promoter of TERT, which encodes an enzyme implicated in the cancer’s growth. The findings help explain why therapies that target protein-coding mutations don’t work in brain cancer when they do in other tumor types. They also point to new drug targets.

Emerging strategies for delivering antiangiogenic therapies to primary and metastatic brain tumors

Five-year survival rates have not increased appreciably for patients with primary and metastatic brain tumors. Nearly 17,000 patients die from primary brain tumors, whereas approximately 200,000 cases are diagnosed with brain metastasis every year in the US alone. At the same time, with improved control of systemic disease, the incidence of brain metastasis is increasing. Thus, novel approaches for improving the treatment outcome for these uniformly fatal diseases are needed urgently. In the review, we summarize the challenges in the treatment of these diseases using antiangiogenic therapies alone or in combination with radio-, chemo- and immuno-therapies. We also discuss the emerging strategies to improve the treatment outcome using both pharmacological approaches to normalize the tumor microenvironment and physical approaches (e.g., focused ultrasound) to modulate the blood-tumor-barrier, along with limitations of each approach. Finally, we offer some new avenues of future research.

EGFR and EGFRvIII Promote Angiogenesis and Cell Invasion in Glioblastoma: Combination Therapies for an Effective Treatment

Epidermal growth factor receptor (EGFR) and the mutant EGFRvIII are major focal points in current concepts of targeted cancer therapy for glioblastoma multiforme (GBM), the most malignant primary brain tumor. The receptors participate in the key processes of tumor cell invasion and tumor-related angiogenesis and their upregulation correlates with the poor prognosis of glioma patients. Glioma cell invasion and increased angiogenesis share mechanisms of the degradation of the extracellular matrix (ECM) through upregulation of ECM-degrading proteases as well as the activation of aberrant signaling pathways. This review describes the role of EGFR and EGFRvIII in those mechanisms which might offer new combined therapeutic approaches targeting EGFR or EGFRvIII together with drug treatments against proteases of the ECM or downstream signaling to increase the inhibitory effects of mono-therapies.

New Directions in Anti-Angiogenic Therapy for Glioblastoma

Anti-angiogenic therapy has become an important component in the treatment of many solid tumors given the importance of adequate blood supply for tumor growth and metastasis. Despite promising preclinical data and early clinical trials, anti-angiogenic agents have failed to show a survival benefit in randomized controlled trials of patients with glioblastoma. In particular, agents targeting vascular endothelial growth factor (VEGF) appear to prolong progression free survival, possibly improve quality of life, and decrease steroid usage, yet the trials to date have demonstrated no extension of overall survival. In order to improve duration of response and convey a survival benefit, additional research is still needed to explore alternative pro-angiogenic pathways, mechanisms of resistance, combination strategies, and biomarkers to predict therapeutic response.

EGFR as a Target for Glioblastoma Treatment: An Unfulfilled Promise

The receptor for epidermal growth factor (EGFR) is a prime target for cancer therapy across a broad variety of tumor types. As it is a tyrosine kinase, small molecule tyrosine kinase inhibitors (TKIs) targeting signal transduction, as well as monoclonal antibodies against the EGFR, have been investigated as anti-tumor agents. However, despite the long-known enigmatic EGFR gene amplification and protein overexpression in glioblastoma, the most aggressive intrinsic human brain tumor, the potential of EGFR as a target for this tumor type has been unfulfilled. This review analyses the attempts to use TKIs and monoclonal antibodies against glioblastoma, with special consideration given to immunological approaches, the use of EGFR as a docking molecule for conjugates with toxins, T-cells, oncolytic viruses, exosomes and nanoparticles. Drug delivery issues associated with therapies for intracerebral diseases, with specific emphasis on convection enhanced delivery, are also discussed.