Recurrence pattern in glioblastoma multiforme patients treated with anti-angiogenic chemotherapy

Development of Novel VEGFR2 Inhibitors Originating from Natural Product Analogues with Antiangiogenic Impact

A novel natural small molecule, voacangine (Voa), has been discovered as a potent antiangiogenic compound. Notably, Voa directly binds the kinase domain of the vascular endothelial growth factor receptor 2 (VEGFR2) and thereby inhibits downstream signaling. Herein, we developed synthetic small molecules based on the unique chemical structure of Voa that directly and specifically target and modulate the kinase activity of VEGFR2. Among these Voa structure analogues, Voa analogue 19 (V19) exhibited increased antiangiogenic potency against VEGF-induced VEGFR2 phosphorylation without cytotoxic effects. Moreover, treatment with V19 resulted in significant tumor cell death in a mouse xenograft model. In conclusion, this new VEGFR2 modulator, inspired from the rigid scaffold of a natural compound, Voa, is presented as a potent candidate in the development of new antiangiogenic agents.

Evaluation of Thymidine Phosphorylase Inhibitors in Glioblastoma and Their Capacity for Temozolomide Potentiation

A number of studies have shown high levels of thymidine phosphorylase (TP) expression in glioblastoma (GBM), with trace or undetectable TP levels in normal developed brain tissue. TP catalyzes the reversible phosphorolysis of thymidine to thymine and 2-deoxyribose-1-phosphate, maintaining nucleoside homeostasis for efficient DNA replication and cell division. The TP-mediated catabolism of thymidine is responsible for multiple protumor processes and can support angiogenesis, glycation of proteins, and alternative metabolism. In this study, we examined the effect of TP inhibition in GBM using the known nanomolar TP inhibitors 5-chloro-6-[1-(2'-iminopyrrolidin-1'-yl)methyl]uracil (TPI) and the analogous 6-[(2'-aminoimidazol-1'-yl)methyl]uracils. Although these TP inhibitors did not demonstrate any appreciable cytotoxicity in GBM cell lines as single agents, they did enhance the cytotoxicity of temozolomide (TMZ). This pontetiated action of TMZ by TP inhibition may be due to limiting the availability of thymine for DNA repair and replication. These studies support that TP inhibitors could be used as chemosensitizing agents in GBM to improve the efficacy of TMZ.

Radiological Recurrence Patterns after Bevacizumab Treatment of Recurrent High-Grade Glioma: A Systematic Review and Meta-Analysis

Objective

To categorize the radiological patterns of recurrence after bevacizumab treatment and to derive the pooled proportions of patients with recurrent malignant glioma showing the different radiological patterns.

Materials and Methods

A systematic literature search in the Ovid-MEDLINE and EMBASE databases was performed to identify studies reporting radiological recurrence patterns in patients with recurrent malignant glioma after bevacizumab treatment failure until April 10, 2019. The pooled proportions according to radiological recurrence patterns (geographically local versus non-local recurrence) and predominant tumor portions (enhancing tumor versus non-enhancing tumor) after bevacizumab treatment were calculated. Subgroup and meta-regression analyses were also performed.

Results

The systematic review and meta-analysis included 17 articles. The pooled proportions were 38.3% (95% confidence interval [CI], 30.6–46.1%) for a geographical radiologic pattern of non-local recurrence and 34.2% (95% CI, 27.3–41.5%) for a non-enhancing tumor-predominant recurrence pattern. In the subgroup analysis, the pooled proportion of non-local recurrence in the patients treated with bevacizumab only was slightly higher than that in patients treated with the combination with cytotoxic chemotherapy (34.9% [95% CI, 22.8–49.4%] versus 22.5% [95% CI, 9.5–44.6%]).

Conclusion

A substantial proportion of high-grade glioma patients show non-local or non-enhancing radiologic patterns of recurrence after bevacizumab treatment, which may provide insight into surrogate endpoints for treatment failure in clinical trials of recurrent high-grade glioma.

A 3D bioprinted hydrogel mesh loaded with all-trans retinoic acid for treatment of glioblastoma

Treatment of glioblastoma (GBM), as the most lethal type of brain tumor, still remains a major challenge despite the various therapeutic approaches developed over the recent decades. GBM is considered as one of the most therapy-resistant human tumors. Treatment with temozolomide (TMZ) chemotherapy and radiotherapy in GBM patients has led to 30% of two-year survival rate (American Brain Tumor Association), representing a demanding field to develop more effective therapeutic strategies. This study presents a novel method for local delivery of all-trans retinoic acid (ATRA) for targeting GBM cells as a possible adjuvant therapeutic strategy for this disease. We have used 3D bioprinting to fabricate hydrogel meshes laden with ATRA-loaded polymeric particles. The ATRA-loaded meshes have been shown to facilitate a sustained release of ATRA with tunable release rate. Cell viability assay was used to demonstrate the ability of fabricated meshes in reducing cell growth in U-87 MG cell line. We later showed that the developed meshes induced apoptotic cell death in U-87 MG. Furthermore, the use of hydrogel for embedding the ATRA-loaded particles can facilitate the immobilization of the drug next to the tumor site. Our current innovative approach has shown the potential to open up new avenues for treatment of GBM, benefiting patients who suffer from this debilitating disease.

Neuroimaging classification of progression patterns in glioblastoma: a systematic review

BACKGROUND

Our primary objective was to report the current neuroimaging classification systems of spatial patterns of progression in glioblastoma. In addition, we aimed to report the terminology used to describe 'progression' and to assess the compliance with the Response Assessment in Neuro-Oncology (RANO) Criteria.

METHODS

We conducted a systematic review to identify all neuroimaging studies of glioblastoma that have employed a categorical classification system of spatial progression patterns. Our review was registered with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) registry.

RESULTS

From the included 157 results, we identified 129 studies that used labels of spatial progression patterns that were not based on radiation volumes (Group 1) and 50 studies that used labels that were based on radiation volumes (Group 2). In Group 1, we found 113 individual labels and the most frequent were: local/localised (58%), distant/distal (51%), diffuse (20%), multifocal (15%) and subependymal/subventricular zone (15%). We identified 13 different labels used to refer to 'progression', of which the most frequent were 'recurrence' (99%) and 'progression' (92%). We identified that 37% (n = 33/90) of the studies published following the release of the RANO classification were adherent compliant with the RANO criteria.

CONCLUSIONS

Our review reports significant heterogeneity in the published systems used to classify glioblastoma spatial progression patterns. Standardization of terminology and classification systems used in studying progression would increase the efficiency of our research in our attempts to more successfully treat glioblastoma.

Quantitative Immunohistochemistry of the Cellular Microenvironment in Patient Glioblastoma Resections

With the growing interest in the tumor microenvironment, we set out to develop a method to specifically determine the microenvironment components within patient samples of glioblastoma, the deadliest and most invasive brain cancer. Not only are quantitative methods beneficial for accurately describing diseased tissues, they can also potentially contribute to more accurate prognosis, diagnosis, and the development of tissue-engineered systems and replacements. In glioblastoma, glial cells, such as microglia and astrocytes, have been independently correlated with poor prognosis based on pathologist grading. However, the state of these cells and other glial cell components has not been well-described quantitatively. This can be difficult due to the large processes that mark these glial cells. Furthermore, most histological analyses focus on the overall tissue sample or only within the bulk of the tumor, as opposed to delineating quantifications based on regions within the highly heterogeneous tissue. Here, we describe a method for identifying and quantitatively analyzing the populations of glial cells within the tumor bulk and adjacent regions of tumor resections from glioblastoma patients. We used chromogenic immunohistochemistry to identify the glial cell populations in patient tumor resections and ImageJ to analyze percent coverage of staining for each glial population. With these techniques we are able to better describe the glial cells throughout regions of the glioma tumor microenvironment.

Do Increased Doses to Stem-Cell Niches during Radiation Therapy Improve Glioblastoma Survival?

Background and Purpose. The reasons for the inevitable glioblastoma recurrence are yet understood. However, recent data suggest that tumor cancer stem cells (CSCs) in the stem-cell niches, with self-renewing capacities, might be responsible for tumor initiation, propagation, and recurrence. We aimed to analyze the effect of higher radiation doses to the stem-cell niches on progression-free survival (PFS) and overall survival (OS) in glioblastoma patients. Materials and Methods. Sixty-five patients with primary glioblastoma treated with radiation therapy were included in this retrospective analysis. The SVZ and DG were segmented on treatment planning magnetic resonance imaging, and the dose distributions to the structures were calculated. The relationship of dosimetry data and survival was evaluated using the Cox regression analysis. Results. Conventionally fractionated patients (n = 54) who received higher doses (D_mean ≥ 40 Gy) to the IL SVZ showed improved PFS (8.5 versus 5.2 months; p = 0.013). Furthermore, higher doses (D_mean ≥ 30 Gy) to the CL SVZ were associated with increased PFS (10.1 versus 6.9 months; p = 0.025). Conclusion. Moderate higher IL SVZ doses (≥40 Gy) and CL SVZ doses (≥30 Gy) are associated with improved PFS. Higher doses to the DG, the second stem-cell niche, did not influence the survival. Targeting the potential cancer stem cells in the SVZ might be a promising treatment approach for glioblastoma and should be addressed in a prospective randomized trial.

Diffusion-weighted MRI as a biomarker for treatment response in glioma

Diffusion-weighted imaging (DWI) is a powerful MRI method, which probes abnormalities of tissue structure by detecting microscopic changes in water mobility at a cellular level beyond what is available with other imaging techniques. Accordingly, DWI has the potential to identify pathology before gross anatomic changes are evident on standard anatomical brain images. These features of tissue characterization and earlier detection are what make DWI particularly appealing for the evaluation of gliomas and the newer therapies where standard anatomical imaging is proving insufficient. This article focuses on the basic principles and applications of DWI, and its derived parameter, the apparent diffusion coefficient, for the purposes of diagnosis and evaluation of glioma, especially in the context of monitoring response to therapy.

Guiding intracortical brain tumour cells to an extracortical cytotoxic hydrogel using aligned polymeric nanofibres

Glioblastoma multiforme is an aggressive, invasive brain tumour with a poor survival rate. Available treatments are ineffective and some tumours remain inoperable because of their size or location. The tumours are known to invade and migrate along white matter tracts and blood vessels. Here, we exploit this characteristic of glioblastoma multiforme by engineering aligned polycaprolactone (PCL)-based nanofibres for tumour cells to invade and, hence, guide cells away from the primary tumour site to an extracortical location. This extracortial sink is a cyclopamine drug-conjugated, collagen-based hydrogel. When aligned PCL-nanofibre films in a PCL/polyurethane carrier conduit were inserted in the vicinity of an intracortical human U87MG glioblastoma xenograft, a significant number of human glioblastoma cells migrated along the aligned nanofibre films and underwent apoptosis in the extracortical hydrogel. Tumour volume in the brain was significantly lower following insertion of aligned nanofibre implants compared with the application of smooth fibres or no implants.

Paediatric spinal glioblastoma: case report and review of therapeutic strategies

INTRODUCTION

Although uncommon, there is significant morbidity and mortality associated with paediatric spinal glioblastoma. The paucity of cases makes treatment options difficult. The current recommended standard of care is biopsy followed by adjuvant chemo-radiotherapy, with emerging data supporting the role of safe gross total resection.

OBJECTIVE

The purpose of this paper is to provide a single-institution case study and to discuss current and future therapeutic treatment strategies.

CASE PRESENTATION

A 14-year-old boy presented with a 2-year history of intermittent back pain with recent progressively worsening motor and sensory deficits of the right side. Pre-operative MRI revealed an enhancing intra-medullary tumour extending from C2 to C7. During the operative case, no tumour-cord margin could be identified, and the patient underwent a subtotal excision. Histopathology confirmed glioblastoma. In the subsequent weeks, the patient's clinical condition deteriorated. Adjuvant therapy was declined by the family, and the patient died 9 weeks after initial presentation.

CONCLUSION

Despite major advances in surgical techniques, peri-operative neuro-imaging as well as chemo-radiotherapy, the prognosis of a paediatric intra-medullary high-grade spinal tumour remains poor. Detailed analysis of our understanding of tumour dynamics in this patient group is important in establishing future therapeutic strategies.

Canadian recommendations for the treatment of recurrent or progressive glioblastoma multiforme

Recommendation 1: Multidisciplinary ApproachTo optimize treatment outcomes, the management of patients with recurrent glioblastoma should be individualized and should involve a multidisciplinary team approach, including neurosurgery, neuropathology, radiation oncology, neuro-oncology, and allied health professions.Recommendation 2: ImagingThe standard imaging modality for assessment of recurrent glioblastoma is Gd-enhanced magnetic resonance imaging (mri). Tumour recurrence should be assessed according to the criteria set out by the Response Assessment in Neuro-Oncology Working Group. The optimal timing and frequency of mri after chemoradiation and adjunctive therapy have not been established.Recommendation 3: Pseudo-progressionProgression observed by mri after chemoradiation can be pseudo-progression. Accordingly, treated patients should not be classified as having progressive disease by Gd-enhancing mri within the first 12 weeks after the end of radiotherapy unless new enhancement is observed outside the radiotherapy field or viable tumour is confirmed by pathology at the time of a required re-operation. Adjuvant temozolomide should be continued and follow-up imaging obtained.Recommendation 4: Repeat SurgerySurgery can play a role in providing symptom relief and confirming tumour recurrence, pseudo-progression, or radiation necrosis. However, before surgical intervention, it is essential to clearly define treatment goals and the expected impact on prognosis and the patient's quality of life. In the absence of level 1 evidence, the decision to re-operate should be made according to individual circumstances, in consultation with the multidisciplinary team and the patient.Recommendation 5: Re-irradiationRe-irradiation is seldom recommended, but can be considered in carefully selected cases of recurrent glioblastoma.Recommendation 6: Systemic TherapyClinical trials, when available, should be offered to all eligible patients. In the absence of a trial, systemic therapy, including temozolomide rechallenge or anti-angiogenic therapy, may be considered. Combination therapy is still experimental; optimal drug combinations and sequencing have not been established.

Stem cells in brain tumour development and therapy- two-sides of the same coin

Primary brain tumours are difficult to manage clinically due to their abilities to invade adjacent tissue and infiltrate distant neuropil. These contribute to challenges in surgical management and also limit the effectiveness of radiotherapy. Despite initial responses to chemotherapy, most tumours become chemo-resistant, leading to relapse. Recent identification and isolation of brain cancer stem cells (BCSCs) have broadened our understanding of the molecular pathogenesis and potential Achilles' heel of brain tumours. BCSCs are thought to drive and propagate the tumour and therefore present an important target for further investigations. This review explores the history of the discovery of BCSCs and the evolving concept of "cancer stem cells" in neuro-oncology. We attempt to present a balanced view on the subject and also to update the readers on the molecular biology of BCSCs. Lastly, we outline the potential strategies to target BCSCs which will translate into specific and effective therapies for brain tumours.

Propentofylline targets TROY, a novel microglial signaling pathway

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain cancer, with a median survival of less than 2 years after diagnosis with current available therapies. The tumor microenvironment serves a critical role in tumor invasion and progression, with microglia as a critical player. Our laboratory has previously demonstrated that propentofylline, an atypical methylxanthine with central nervous system glial modulating and anti-inflammatory actions, significantly decreases tumor growth in a GBM rodent model by preferentially targeting microglia. In the present study, we used the CNS-1 rat glioma model to elucidate the mechanisms of propentofylline. Here we demonstrate that propentofylline targets TROY, a novel signaling molecule up-regulated in infiltrating microglia, and not macrophages, in response to CNS-1 cells. We identify Pyk2, Rac1 and pJNK as the downstream signaling molecules of TROY through western blot analysis and siRNA transfection. We demonstrate that inhibition of TROY expression in microglia by siRNA transfection significantly inhibits microglial migration towards CNS-1 cells similar to 10 µM propentofylline treatment. These results identify TROY as a novel molecule expressed in microglia, involved in their migration and targeted by propentofylline. Furthermore, these results describe a signaling molecule that is differentially expressed between microglia and macrophages in the tumor microenvironment.

The use of fluorescent proteins for intravital imaging of cancer cell invasion

The analysis of cancer cell behavior in the primary tumor in living animals provides an opportunity to explore the process of invasion and intravasation in the complex microenvironment that is present in vivo. In this chapter, we describe the methods that we have developed for performing intravital imaging of mammary tumors. We provide procedures for generating tumors through injection of tumor cell lines, and multiphoton imaging using a skin-flap tumor dissection and a mammary imaging window.

Propentofylline decreases tumor growth in a rodent model of glioblastoma multiforme by a direct mechanism on microglia

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain cancer, with a median survival of less than 2 years after diagnosis. The tumor microenvironment plays a critical role in tumor invasion and progression. Microglia and infiltrating macrophages are the most abundant immune cells in the tumor. In the present study, we demonstrate that systemic propentofylline (PPF), an atypical methylxanthine with central nervous system (CNS) glial modulating and anti-inflammatory actions, significantly decreased tumor growth in a CNS-1 rat model of GBM by targeting microglia and not tumor cells. Rats received tumor injections of 1 × 10(5) CNS-1 cells in the right striatum with daily intraperitonial injections of PPF (50 mg/kg) or saline beginning the day of tumor injection. PPF did not cause apoptosis or decrease proliferation of CNS-1 tumor cells. Furthermore, we demonstrate, using in vitro methods, that PPF decreased microglial migration toward CNS-1 tumor cells and decreased MMP-9 expression. The effects of PPF were shown to be specific to microglia and not peripheral macrophages. These results support a differential functional role of resident microglia and infiltrating macrophages in the brain tumor environment. Our data highlight microglia as a crucial target for future therapeutic development and present PPF as a possible drug for treatment of human GBM.

Irradiation of the potential cancer stem cell niches in the adult brain improves progression-free survival of patients with malignant glioma

BACKGROUND

Glioblastoma is the most common brain tumor in adults. The mechanisms leading to glioblastoma are not well understood but animal studies support that inactivation of tumor suppressor genes in neural stem cells (NSC) is required and sufficient to induce glial cancers. This suggests that the NSC niches in the brain may harbor cancer stem cells (CSCs), Thus providing novel therapy targets. We hypothesize that higher radiation doses to these NSC niches improve patient survival by eradicating CSCs.

METHODS

55 adult patients with Grade 3 or Grade 4 glial cancer treated with radiotherapy at UCLA between February of 2003 and May of 2009 were included in this retrospective study. Using radiation planning software and patient radiological records, the SVZ and SGL were reconstructed for each of these patients and dosimetry data for these structures was calculated.

RESULTS

Using Kaplan-Meier analysis we show that patients whose bilateral subventricular zone (SVZ) received greater than the median SVZ dose (= 43 Gy) had a significant improvement in progression-free survival if compared to patients who received less than the median dose (15.0 vs 7.2 months PFS; P = 0.028). Furthermore, a mean dose >43 Gy to the bilateral SVZ yielded a hazard ratio of 0.73 (P = 0.019). Importantly, similarly analyzing total prescription dose failed to illustrate a statistically significant impact.

CONCLUSIONS

Our study leads us to hypothesize that in glioma targeted radiotherapy of the stem cell niches in the adult brain could yield significant benefits over radiotherapy of the primary tumor mass alone and that damage caused by smaller fractions of radiation maybe less efficiently detected by the DNA repair mechanisms in CSCs.

Update and developments in the treatment of glioblastoma multiforme - focus on bevacizumab

Glioblastoma is the most common primary brain tumor with a relatively poor prognosis. This article reviews the current standard therapy and discusses new developments in treatment of this disease. Surgical resection followed by radiation and chemotherapy has proven to be the most effective initial therapy. Recent advancement in molecular targeted therapies has led to the Food and Drug Administration (FDA) approval of bevacizumab in the setting of recurrent glioblastoma. The molecular pathways of glioblastoma growth are highlighted in this review. While numerous molecular targets are currently being intensely investigated, vascular endothelial growth factor (VEGF) receptor targeted therapy has been the only one to have shown clinical effect. The role of bevacizumab in this context provides a dynamic breakthrough in cancer therapy. Clinical trials have demonstrated significantly increased overall survival and six month progression free survival (PFS) in recurrent glioblastoma treated with bevacizumab alone or in combination with irinotecan. The use of this agent has also dramatically changed the imaging characteristics of glioblastoma. The anti-angiogenesis effects of bevacizumab have complicated the criterion for determining tumor growth. This may lead to redefinition of progressive disease based on non-invasive monitoring.

Exciting new advances in neuro-oncology: the avenue to a cure for malignant glioma

Malignant gliomas are the most common and deadly brain tumors. Nevertheless, survival for patients with glioblastoma, the most aggressive glioma, although individually variable, has improved from an average of 10 months to 14 months after diagnosis in the last 5 years due to improvements in the standard of care. Radiotherapy has been of key importance to the treatment of these lesions for decades, and the ability to focus the beam and tailor it to the irregular contours of brain tumors and minimize the dose to nearby critical structures with intensity-modulated or image-guided techniques has improved greatly. Temozolomide, an alkylating agent with simple oral administration and a favorable toxicity profile, is used in conjunction with and after radiotherapy. Newer surgical techniques, such as fluorescence-guided resection and neuroendoscopic approaches, have become important in the management of malignant gliomas. Furthermore, new discoveries are being made in basic and translational research, which are likely to improve this situation further in the next 10 years. These include agents that block 1 or more of the disordered tumor proliferation signaling pathways, and that overcome resistance to already existing treatments. Targeted therapies such as antiangiogenic therapy with antivascular endothelial growth factor antibodies (bevacizumab) are finding their way into clinical practice. Large-scale research efforts are ongoing to provide a comprehensive understanding of all the genetic alterations and gene expression changes underlying glioma formation. These have already refined the classification of glioblastoma into 4 distinct molecular entities that may lead to different treatment regimens. The role of cancer stem-like cells is another area of active investigation. There is definite hope that by 2020, new cocktails of drugs will be available to target the key molecular pathways involved in gliomas and reduce their mortality and morbidity, a positive development for patients, their families, and medical professionals alike.

Far-distant metastases along the CSF pathway of glioblastoma multiforme during continuous low-dose chemotherapy with temozolomide and celecoxib

Glioblastoma multiforme is the most common and most malignant primary brain tumour. Prognosis after diagnosis remains poor despite recent advances in adjuvant therapy. Treatment of choice is gross surgical resection and combined radio-chemotherapy with temozolomide as chemotherapeutic agent. Experimental continuous low-dose chemotherapy with temozolomide in combination with a cyclooxygenase-2 inhibitor has shown encouraging effects on progression-free survival and overall survival in patients, but leads to a high proportion of distant recurrences. Here, we describe extreme far-distant metastases along the neural axis of glioblastoma multiforme in four patients receiving metronomic antiangiogenic chemotherapy and review the literature to discuss possible mechanisms.