Glioblastoma multiforme: an emerging paradigm of anti-VEGF therapy

Wnt Signaling in Brain Tumors: A Challenging Therapeutic Target

The involvement of Wnt signaling in normal tissue homeostasis and disease has been widely demonstrated over the last 20 years. In particular, dysregulation of Wnt pathway components has been suggested as a relevant hallmark of several neoplastic malignancies, playing a role in cancer onset, progression, and response to treatments. In this review, we summarize the current knowledge on the instructions provided by Wnt signaling during organogenesis and, particularly, brain development. Moreover, we recapitulate the most relevant mechanisms through which aberrant Wnt pathway activation may impact on brain tumorigenesis and brain tumor aggressiveness, with a particular focus on the mutual interdependency existing between Wnt signaling components and the brain tumor microenvironment. Finally, the latest anti-cancer therapeutic approaches employing the specific targeting of Wnt signaling are extensively reviewed and discussed. In conclusion, here we provide evidence that Wnt signaling, due to its pleiotropic involvement in several brain tumor features, may represent a relevant target in this context, although additional efforts will be needed to: (i) demonstrate the real clinical impact of Wnt inhibition in these tumors; (ii) overcome some still unsolved concerns about the potential systemic effects of such approaches; (iii) achieve efficient brain penetration.

The Utility of Conventional Amino Acid PET Radiotracers in the Evaluation of Glioma Recurrence also in Comparison with MRI

AIM

In this comprehensive review we present an update on the most relevant studies evaluating the utility of amino acid PET radiotracers for the evaluation of glioma recurrence as compared to magnetic resonance imaging (MRI).

METHODS

A literature search extended until June 2020 on the PubMed/MEDLINE literature database was conducted using the terms "high-grade glioma", "glioblastoma", "brain tumors", "positron emission tomography", "PET", "amino acid PET", "[¹¹C]methyl-l-methionine", "[¹⁸F]fluoroethyl-tyrosine", "[¹⁸F]fluoro-l-dihydroxy-phenylalanine", "MET", "FET", "DOPA", "magnetic resonance imaging", "MRI", "advanced MRI", "magnetic resonance spectroscopy", "perfusion-weighted imaging", "diffusion-weighted imaging", "MRS", "PWI", "DWI", "hybrid PET/MR", "glioma recurrence", "pseudoprogression", "PSP", "treatment-related change", and "radiation necrosis" alone and in combination. Only original articles edited in English and about humans with at least 10 patients were included.

RESULTS

Forty-four articles were finally selected. Conventional amino acid PET tracers were demonstrated to be reliable diagnostic techniques in differentiating tumor recurrence thanks to their high uptake from tumor tissue and low background in normal grey matter, giving additional and early information to standard modalities. Among them, MET-PET seems to present the highest diagnostic value but its use is limited to on-site cyclotron facilities. [¹⁸F]labelled amino acids, such as FDOPA and FET, were developed to provide a more suitable PET tracer for routine clinical applications, and demonstrated similar diagnostic performance. When compared to the gold standard MRI, amino acid PET provides complementary and comparable information to standard modalities and seems to represent an essential tool in the differentiation between tumor recurrence and other entities such as pseudoprogression, radiation necrosis, and pseudoresponse.

CONCLUSIONS

Despite the introduction of new advanced imaging techniques, the diagnosis of glioma recurrence remains challenging. In this scenario, the growing knowledge about imaging techniques and analysis, such as the combined PET/MRI and the application of artificial intelligence (AI) and machine learning (ML), could represent promising tools to face this difficult and debated clinical issue.

Screening the Significant Hub Genes by Comparing Tumor Cells, Normoxic and Hypoxic Glioblastoma Stem-like Cell Lines Using Co-Expression Analysis in Glioblastoma

Glioblastoma multiforme (GBM) is categorized by rapid malignant cellular growth in the central nervous system (CNS) tumors. It is one of the most prevailing primary brain tumors, particularly in human male adults. Even though the combination therapy comprises surgery, chemotherapy, and adjuvant therapies, the survival rate is on average 14.6 months. Glioma stem cells (GSCs) have key roles in tumorigenesis, progression, and counteracting chemotherapy and radiotherapy. In our study, firstly, the gene expression dataset GSE45117 was retrieved and differentially expressed genes (DEGs) were spotted. The co-expression network analysis was employed on DEGs to find the significant modules. The most significant module resulting from co-expression analysis was the turquoise module. The turquoise module related to the tumor cells, hypoxia, normoxic treatments of glioblastoma tumor (GBT), and GSCs were screened. Sixty-one common genes in the turquoise module were selected generated through the co-expression analysis and protein–protein interaction (PPI) network. Moreover, the GO and KEGG pathway enrichment results were studied. Twenty common hub genes were screened by the NetworkAnalyst web instrument constructed on the PPI network through the STRING database. After survival analysis via the Kaplan–Meier (KM) plotter from The Cancer Genome Atlas (TCGA) database, we identified the five most significant hub genes strongly related to the progression of GBM. We further observed these five most significant hub genes also up-regulated in another GBM gene expression dataset. The protein–protein interaction (PPI) network of the turquoise module genes was constructed and a KEGG pathway enrichments study of the turquoise module genes was performed. The VEGF signaling pathway was emphasized because of the strong link with GBM. A gene–disease association network was further constructed to demonstrate the information of the progression of GBM and other related brain neoplasms. All hub genes assessed through this study would be potential markers for the prognosis and diagnosis of GBM.

Present and Future of Anti-Glioblastoma Therapies: A Deep Look into Molecular Dependencies/Features

Glioblastoma (GBM) is aggressive malignant tumor residing within the central nervous system. Although the standard treatment options, consisting of surgical resection followed by combined radiochemotherapy, have long been established for patients with GBM, the prognosis is still poor. Despite recent advances in diagnosis, surgical techniques, and therapeutic approaches, the increased patient survival after such interventions is still sub-optimal. The unique characteristics of GBM, including highly infiltrative nature, hard-to-access location (mainly due to the existence of the blood brain barrier), frequent and rapid recurrence, and multiple drug resistance mechanisms, pose challenges to the development of an effective treatment. To overcome current limitations on GBM therapy and devise ideal therapeutic strategies, efforts should focus on an improved molecular understanding of GBM pathogenesis. In this review, we summarize the molecular basis for the development and progression of GBM as well as some emerging therapeutic approaches.

Small molecule tyrosine kinase inhibitors in glioblastoma

Glioblastoma (GBM) is the most common malignant primary brain tumor, with poor survival despite treatment with surgery, radiotherapy, and chemotherapy with temozolomide. Little progress has been made over the last two decades, and there remain unmet medical needs. Approximately 45% of patients with GBM carry EGFR mutations, and 13% of them possess altered PDGFR genes. Moreover, VEGF/VEGFR mutations are also observed in the patient population. Tyrosine kinase inhibitors (TKIs) are emerging cancer therapy drugs that inhibit signal transduction cascades affecting cell proliferation, migration, and angiogenesis. Indications for small molecule TKIs have been successfully expanded to multiple types of cancer; however, none of the TKIs have been approved for patients with GBM. In this review, we summarize clinical trials of small molecule TKIs in patients with GBM and plausible hypotheses for negative clinical study results. We also discuss the potential TKI candidates that presented significant preclinical outcomes in patients with GBM.

Response Assessment in Neuro-Oncology Criteria for Gliomas: Practical Approach Using Conventional and Advanced Techniques

The Response Assessment in Neuro-Oncology criteria were developed as an objective tool for radiologic assessment of treatment response in high-grade gliomas. Imaging plays a critical role in the management of the patient with glioma, from initial diagnosis to posttreatment follow-up, which can be particularly challenging for radiologists. Interpreting findings after surgery, radiation, and chemotherapy requires profound knowledge about the tumor biology, as well as the peculiar changes expected to ensue as a consequence of each treatment technique. In this article, we discuss the imaging findings associated with tumor progression, tumor response, pseudoprogression, and pseudoresponse according to the Response Assessment in Neuro-Oncology criteria for high-grade and lower-grade gliomas. We describe relevant practical issues when evaluating patients with glioma, such as the need for imaging in the first 48 hours, the radiation therapy planning and isodose curves, the significance of T2/FLAIR hyperintense lesions, the impact of the timing for the evaluation after radiation therapy, and the definition of progressive disease on the histologic specimen. We also illustrate the correlation among the findings on conventional MR imaging with advanced techniques, such as perfusion, diffusion-weighted imaging, spectroscopy, and amino acid PET. Because many of the new lesions represent a mixture of tumor cells and tissue with radiation injury, the radiologist aims to identify the predominant component of the lesion and categorize the findings according to Response Assessment in Neuro-Oncology criteria so that the patient can receive the best treatment.

Imaging signatures of glioblastoma molecular characteristics: A radiogenomics review

Over the past few decades, the advent and development of genomic assessment methods and computational approaches have raised the hopes for identifying therapeutic targets that may aid in the treatment of glioblastoma. However, the targeted therapies have barely been successful in their effort to cure glioblastoma patients, leaving them with a grim prognosis. Glioblastoma exhibits high heterogeneity, both spatially and temporally. The existence of different genetic subpopulations in glioblastoma allows this tumor to adapt itself to environmental forces. Therefore, patients with glioblastoma respond poorly to the prescribed therapies, as treatments are directed towards the whole tumor and not to the specific genetic subregions. Genomic alterations within the tumor develop distinct radiographic phenotypes. In this regard, MRI plays a key role in characterizing molecular signatures of glioblastoma, based on regional variations and phenotypic presentation of the tumor. Radiogenomics has emerged as a (relatively) new field of research to explore the connections between genetic alterations and imaging features. Radiogenomics offers numerous advantages, including noninvasive and global assessment of the tumor and its response to therapies. In this review, we summarize the potential role of radiogenomic techniques to stratify patients according to their specific tumor characteristics with the goal of designing patient-specific therapies. Level of Evidence: 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;52:54-69.

Current Approaches and Challenges in the Molecular Therapeutic Targeting of Glioblastoma

Surgical resection continues to predominate as the primary treatment modality in glioblastoma (GBM). Effective chemotherapeutic/biologic agents capable of targeting GBM have yet to be developed in part because of the exceptionally heterogeneous nature and unique microenvironmental conditions associated with this malignant neoplasm. Temozolomide and bevacizumab represent the only U.S. Food and Drug Administration-approved agents for primary and recurrent GBM, respectively. Given the high therapeutic resistance of GBM to current therapies, as well as the failure of bevacizumab to prolong overall survival, new therapeutic agents are urgently warranted and are now in the preclinical and clinical phases of development. Accordingly, clinical trials evaluating the efficacy of immune checkpoint inhibition, chimeric antigen receptor T cell therapy, virotherapies, and tumor vaccination therapy are all under way in GBM. Herein, we review the application of current/novel therapeutics in GBM and in so doing attempt to highlight the most promising solutions to overcome current failures.

Amentoflavone Effectively Blocked the Tumor Progression of Glioblastoma via Suppression of ERK/NF- κ B Signaling Pathway

Glioblastoma is the most common primary malignant tumor of the central nervous system, with an annual incidence of 5.26 per 100000 people. The clinical outcome of standard therapy and the survival rate remain poor; therefore, there is an unmet need for a new strategy to treat this lethal disease. Although amentoflavone was known to have anticancer potential in various types of cancers, its antiglioblastoma ability and mechanism remain unrecognized. We demonstrated that amentoflavone may suppress glioblastoma invasion and migration by transwell assay. Moreover, we established NF- κ B reporter gene system and used that for verifying NF- κ B inhibition efficacy of amentoflavone on in vitro and in vivo studies. Here, we indicated that amentoflavone not only diminished NF- κ B activation, but also reduced NF- κ B-mediated downstream oncogenes expression, such as MMP-2, MMP-9, XIAP, cyclinD1 and VEGF, which was elucidated by Western blot and immunohistochemistry (IHC). Tumor growth inhibition and NF- κ B reduction was found in the amentoflavone treatment group, which was revealed by the glioblastoma-bearing animal model. In this study, we also used ERK inhibitor and NF- κ B inhibitor (QNZ) to confirm whether the beneficial result of amentoflavone on glioblastoma was mainly regulated by blockage of ERK/NF- κ B signaling. In summary, ERK/NF- κ B signaling pathway has a role in the inhibition of tumor growth by amentoflavone in glioblastoma.

The Role of Wnt Signal in Glioblastoma Development and Progression: A Possible New Pharmacological Target for the Therapy of This Tumor

Wnt is a complex signaling pathway involved in the regulation of crucial biological functions such as development, proliferation, differentiation and migration of cells, mainly stem cells, which are virtually present in all embryonic and adult tissues. Conversely, dysregulation of Wnt signal is implicated in development/progression/invasiveness of different kinds of tumors, wherein a certain number of multipotent cells, namely “cancer stem cells”, are characterized by high self-renewal and aggressiveness. Hence, the pharmacological modulation of Wnt pathway could be of particular interest, especially in tumors for which the current standard therapy results to be unsuccessful. This might be the case of glioblastoma multiforme (GBM), one of the most lethal, aggressive and recurrent brain cancers, probably due to the presence of highly malignant GBM stem cells (GSCs) as well as to a dysregulation of Wnt system. By examining the most recent literature, here we point out several factors in the Wnt pathway that are altered in human GBM and derived GSCs, as well as new molecular strategies or experimental drugs able to modulate/inhibit aberrant Wnt signal. Altogether, these aspects serve to emphasize the existence of alternative pharmacological targets that may be useful to develop novel therapies for GBM.

Targeting WNT Signaling for Multifaceted Glioblastoma Therapy

The WNT signaling pathway has been of great interest to developmental biologists for decades and has more recently become a central topic for study in cancer biology. It is vital for cell growth and regulation of embryogenesis in many organ systems, particularly the CNS and its associated vasculature. We summarize the role of WNT in CNS development and describe how WNT signaling makes key contributions to malignant glioma stemness, invasiveness, therapeutic resistance, and angiogenesis. The role of WNT in these mechanisms, along with creation and maintainance of the blood-brain barrier (BBB), points to the potential of WNT as a multi-faceted target in malignant glioma therapy.

RUNX1 Regulates Migration, Invasion, and Angiogenesis via p38 MAPK Pathway in Human Glioblastoma

Runt-related transcription factor 1 (RUNX1) is essential for the establishment of fetal and adult hematopoiesis and neuronal development. Aberrant expression of RUNX1 led to proliferation and metastasis of several cancers. The aim of the present study was to investigate the role of RUNX1 in migration, invasion, and angiogenesis of human glioblastoma using IL-1β-treated U-87 MG human glioblastoma cells as a model. IL-1β at 10 ng/ml stimulated translocation of RUNX1 into the nucleus with increased expressions of RUNX1, MMP-1, MMP-2, MMP-9, MMP-19, and VEGFA in U-87 MG cells. In addition, silencing of RUNX1 gene significantly suppressed U-87 MG cell migration and invasion abilities. Moreover, knockdown of RUNX1 mRNA in U-87 MG cells reduced the tube formation of human umbilical vein endothelial cells. Further investigation revealed that IL-1β-induced RUNX1 expression might be mediated via the p38 mitogen-activated protein kinase (MAPK) signaling molecule for the expression of these invasion- and angiogenic-related molecules. Together with an inhibitor of p38 MAPK (SB203580) could decrease RUNX1 mRNA expression. Thus, RUNX1 may be one of the putative molecular targeted therapies against glioma metastasis and angiogenesis through the activation of p38 MAPK signaling pathway.

Internalization of Vectored Liposomes in a Culture of Poorly Differentiated Tumor Cells

Internalization of liposomal nanocontainers conjugated with monoclonal antibodies to VEGF, VEGFR2 (KDR), and proteins overproduced in the tumor tissue was studied in vitro on cultures of poorly differentiated tumor cells. Comparative analysis of accumulation of vectored liposomes in the tumor cells was performed by evaluating co-localization of labeled containers and cell organelles by laser scanning confocal microscopy. We observed nearly 2 times more active penetration and accumulation of liposomes vectored with antibodies in the tumor cells in comparison with non-vectored liposomes. Selective clathrin-dependent penetration of vectored liposomes into tumor cells was demonstrated by using pharmacological agents inhibiting endocytosis.

Targeting Bone Marrow to Potentiate the Anti-Tumor Effect of Tyrosine Kinase Inhibitor in Preclinical Rat Model of Human Glioblastoma

Antiangiogenic agents caused paradoxical increase in pro-growth and pro-angiogenic factors and caused tumor growth in glioblastoma (GBM). It is hypothesized that paradoxical increase in pro-angiogenic factors would mobilize Bone Marrow Derived Cells (BMDCs) to the treated tumor and cause refractory tumor growth. The purposes of the studies were to determine whether whole body irradiation (WBIR) or a CXCR4 antagonist (AMD3100) will potentiate the effect of vatalanib (a VEGFR2 tyrosine kinase inhibitor) and prevent the refractory growth of GBM. Human GBM were grown orthotopically in three groups of rats (control, pretreated with WBIR and AMD3100) and randomly selected for vehicle or vatalanib treatments for 2 weeks. Then all animals underwent Magnetic Resonance Imaging (MRI) followed by euthanasia and histochemical analysis. Tumor volume and different vascular parameters (plasma volume (v_p), forward transfer constant (K^trans), back flow constant (k_ep), extravascular extracellular space volume (v_e) were determined from MRI. In control group, vatalanib treatment increased the tumor growth significantly compared to that of vehicle treatment but by preventing the mobilization of BMDCs and interaction of CXCR4-SDF-1 using WBIR and ADM3100, respectively, paradoxical growth of tumor was controlled. Pretreatment with WBIR or AMD3100 also decreased tumor cell migration, despite the fact that ADM3100 increased the accumulation of M1 and M2 macrophages in the tumors. Vatalanib also increased K^trans and v_e in control animals but both of the vascular parameters were decreased when the animals were pretreated with WBIR and AMD3100. In conclusion, depleting bone marrow cells or CXCR4 interaction can potentiate the effect of vatalanib.

Glioblastoma Stem Cells Microenvironment: The Paracrine Roles of the Niche in Drug and Radioresistance

Among all solid tumors, the high-grade glioma appears to be the most vascularized one. In fact, "microvascular hyperplasia" is a hallmark of GBM. An altered vascular network determines irregular blood flow, so that tumor cells spread rapidly beyond the diffusion distance of oxygen in the tissue, with the consequent formation of hypoxic or anoxic areas, where the bulk of glioblastoma stem cells (GSCs) reside. The response to this event is the induction of angiogenesis, a process mediated by hypoxia inducible factors. However, this new capillary network is not efficient in maintaining a proper oxygen supply to the tumor mass, thereby causing an oxygen gradient within the neoplastic zone. This microenvironment helps GSCs to remain in a "quiescent" state preserving their potential to proliferate and differentiate, thus protecting them by the effects of chemo- and radiotherapy. Recent evidences suggest that responses of glioblastoma to standard therapies are determined by the microenvironment of the niche, where the GSCs reside, allowing a variety of mechanisms that contribute to the chemo- and radioresistance, by preserving GSCs. It is, therefore, crucial to investigate the components/factors of the niche in order to formulate new adjuvant therapies rendering more efficiently the gold standard therapies for this neoplasm.

CCR 20th Anniversary Commentary: Bevacizumab in the Treatment of Glioblastoma--The Progress and the Limitations

Vredenburgh and colleagues conducted the first phase II study of bevacizumab plus irinotecan in recurrent malignant glioma, confirming the safety and efficacy of bevacizumab. This study, which was published in the February 15, 2007, issue of Clinical Cancer Research, was a stepping stone for subsequent research, leading to regulatory approval of bevacizumab for recurrent glioblastoma.

Radiologic Features and Expression of Vascular Endothelial Growth Factor Stratify Survival Outcomes in Patients with Glioblastoma

BACKGROUND AND PURPOSE

Vascular endothelial growth factor is a well-known tumor-specific biomarker that mediates angiogenesis in glioblastoma via hypoxia-dependent mechanisms. Our aim was to investigate the correlation of clinical characteristics, radiologic features, and vascular endothelial growth factor expression with survival outcomes in patients with glioblastoma.

MATERIALS AND METHODS

Clinical and radiologic data of 185 patients with glioblastoma were retrospectively reviewed. Vascular endothelial growth factor expression was examined in all cases via immunohistochemical analysis. Univariate and multivariate analyses were performed to identify the prognostic factors of progression-free survival and overall survival.

RESULTS

Vascular endothelial growth factor expression levels were associated with the presence of ringlike tumor contrast enhancement. Age, preoperative Karnofsky Performance Scale score, gross total resection, and adjuvant therapy were identified as prognostic factors. Among patients undergoing gross total resection, high vascular endothelial growth factor expression was associated with longer progression-free survival (P = .011) and overall survival (P = .039). For tumors with high vascular endothelial growth factor expression, both the non-contrast-enhancing tumor component and peritumoral edema could stratify overall survival (P = .039 and .018, respectively), while only the presence of the non-contrast-enhancing tumor component predicted a longer progression-free survival (P = .024).

CONCLUSIONS

Vascular endothelial growth factor expression level was not an independent prognostic factor in glioblastoma. However, high vascular endothelial growth factor expression might predict longer survival in patients in whom gross total resection was achieved. Furthermore, peritumoral edema and the non-contrast-enhancing tumor component could stratify survival outcomes in patients with high vascular endothelial growth factor tumors.

Recent advance in molecular angiogenesis in glioblastoma: the challenge and hope for anti-angiogenic therapy

Glioblastoma (GBM) is the most highly malignant brain tumor in the human central nerve system. In this paper, we review new and significant molecular findings on angiogenesis and possible resistance mechanisms. Expression of a number of genes and regulators has been shown to be upregulated in GBM microvessel cells, such as interleukin-8, signal transducer and activator of transcription 3, Tax-interacting protein-1, hypoxia induced factor-1 and anterior gradient protein 2. The regulator factors that may strongly promote angiogenesis by promoting endothelial cell metastasis, changing the microenvironment, enhancing the ability of resistance to anti-angiogenic therapy, and that inhibit angiogenesis are reviewed. Based on the current knowledge, several potential targets and strategies are proposed for better therapeutic outcomes, such as its mRNA interference of DII4-Notch signaling pathway and depletion of b1 integrin expression. We also discuss possible mechanisms underlying the resistance to anti-angiogenesis and future directions and challenges in developing new targeted therapy for GBM.

The Dynamics of Interactions Among Immune and Glioblastoma Cells

Glioblastoma is the most common intracranial malignancy that constitutes about 50 % of all gliomas. Despite aggressive, multimodal therapy consisting of surgery, radiation, and chemotherapy, the outcome of patients with glioblastoma remains poor with 5-year survival rates of <10 %. Resistance to conventional therapies is most likely caused by several factors. Alterations in the functions of local immune mediators may represent a critical contributor to this resistance. The tumor microenvironment contains innate and adaptive immune cells in addition to the cancer cells and their surrounding stroma. These various cells communicate with each other by means of direct cell-cell contact or by soluble factors including cytokines and chemokines, and act in autocrine and paracrine manners to modulate tumor growth. There are dynamic interactions among the local immune elements and the tumor cells, where primarily the protective immune cells attempt to overcome the malignant cells. However, by developing somatic mutations and epigenetic modifications, the glioblastoma tumor cells acquire the capability of counteracting the local immune responses, and even exploit the immune cells and products for their own growth benefits. In this review, we survey those immune mechanisms that likely contribute to glioblastoma pathogenesis and may serve as a basis for novel treatment strategies.

The Cancer Genome Atlas Analysis Predicts MicroRNA for Targeting Cancer Growth and Vascularization in Glioblastoma

Using in silico analysis of The Cancer Genome Atlas (TCGA), we identified microRNAs associated with glioblastoma (GBM) survival, and predicted their functions in glioma growth and progression. Inhibition of two "risky" miRNAs, miR-148a and miR-31, in orthotopic xenograft GBM mouse models suppressed tumor growth and thereby prolonged animal survival. Intracranial tumors treated with uncomplexed miR-148a and miR-31 antagomirs exhibited reduced proliferation, stem cell depletion, and normalized tumor vasculature. Growth-promoting functions of these two miRNAs were, in part, mediated by the common target, the factor inhibiting hypoxia-inducible factor 1 (FIH1), and the downstream pathways involving hypoxia-inducible factor HIF1α and Notch signaling. Therefore, miR-31 and miR-148a regulate glioma growth by maintaining tumor stem cells and their niche, and providing the tumor a way to activate angiogenesis even in a normoxic environment. This is the first study that demonstrates intratumoral uptake and growth-inhibiting effects of uncomplexed antagomirs in orthotopic glioma.

VEGFR inhibitors upregulate CXCR4 in VEGF receptor-expressing glioblastoma in a TGFβR signaling-dependent manner

The failure of standard treatment for patients diagnosed with glioblastoma (GBM) coupled with the highly vascularized nature of this solid tumor has led to the consideration of agents targeting VEGF or VEGFRs, as alternative therapeutic strategies for this disease. Despite modest achievements in survival obtained with such treatments, failure to maintain an enduring survival benefit and more invasive relapsing tumors are evident. Our study suggests a potential mechanism by which anti-VEGF/VEGFR therapies regulate the enhanced invasive phenotype through a pathway that involves TGFβR and CXCR4. VEGFR signaling inhibitors (Cediranib and Vandetanib) elevated the expression of CXCR4 in VEGFR-expressing GBM cell lines and tumors, and enhanced the in vitro migration of these lines toward CXCL12. The combination of VEGFR inhibitor and CXCR4 antagonist provided a greater survival benefit to tumor-bearing animals. The upregulation of CXCR4 by VEGFR inhibitors was dependent on TGFβ/TGFβR, but not HGF/MET, signaling activity, suggesting a mechanism of crosstalk among VEGF/VEGFR, TGFβ/TGFβR, and CXCL12/CXCR4 pathways in the malignant phenotype of recurrent tumors after anti-VEGF/VEGFR therapies. Thus, the combination of VEGFR, CXCR4, and TGFβR inhibitors could provide an alternative strategy to halt GBM progression.

VEGF₁₂₁-conjugated mesoporous silica nanoparticle: a tumor targeted drug delivery system

The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) signaling cascade plays a critical role in tumor angiogenesis and metastasis and has been correlated with several poorly prognostic cancers such as malignant gliomas. Although a number of anti-VEGFR therapies have been conceived, inefficient drug administration still limits their therapeutic efficacy and raises concerns of potential side effects. In the present work, we propose the use of uniform mesoporous silica nanoparticles (MSNs) for VEGFR targeted positron emission tomography imaging and delivery of the anti-VEGFR drug (i.e., sunitinib) in human glioblastoma (U87MG) bearing murine models. MSNs were synthesized, characterized and modified with polyethylene glycol, anti-VEGFR ligand VEGF121 and radioisotope (64)Cu, followed by extensive in vitro, in vivo and ex vivo studies. Our results demonstrated that a significantly higher amount of sunitinib could be delivered to the U87MG tumor by targeting VEGFR when compared with the non-targeted counterparts. The as-developed VEGF121-conjugated MSN could become another attractive nanoplatform for the design of future theranostic nanomedicine.

Nitroxoline induces apoptosis and slows glioma growth in vivo

BACKGROUND

Nitroxoline is an FDA-approved antibiotic with potential antitumor activity. Here we evaluated whether nitroxoline has antiproliferative properties on glioma cell growth in vitro and in vivo using glioma cell lines and a genetically engineered PTEN/KRAS mouse glioma model.

METHODS

The effect of nitroxoline treatment on U87 and/or U251 glioma cell proliferation, cell-cycle arrest, invasion, and ability to induce an apoptotic cascade was determined in vitro. Magnetic resonance imaging was used to measure glioma volumes in genetically engineered PTEN/KRAS mice prior to and after nitroxoline therapy. Induction of apoptosis by nitroxoline was evaluated at the end of treatment using terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end labeling (TUNEL).

RESULTS

Nitroxoline inhibited the proliferation and invasion of glioblastoma cells in a time- and dose-dependent manner in vitro. Growth inhibition was associated with cell-cycle arrest in G1/G0 phase and induction of apoptosis via caspase 3 and cleaved poly(ADP-ribose) polymerase. In vivo, nitroxoline-treated mice had no increase in tumor volume after 14 days of treatment, whereas tumor volumes doubled in control mice. Histological examination revealed 15%-20% TUNEL-positive cells in nitroxoline-treated mice, compared with ∼5% in the control group.

CONCLUSION

Nitroxoline induces apoptosis and inhibits glioma growth in vivo and in vitro. As an already FDA-approved treatment for urinary tract infections with a known safety profile, nitroxoline could move quickly into clinical trials pending confirmatory studies.

Bevacizumab for glioblastoma-a promising drug or not?

Two double blind, placebo-controlled, and randomized phase III studies were conducted, and the results including OS’s were reported at the ASCO Meeting in June 2013, which was the beginning of confusion surrounding this topic. This is a review article not only summarizing the previous evidence, but also looking beyond.

Evidence-based risk assessment and recommendations for physical activity clearance: cancer

Physical activity is becoming increasingly acknowledged as an integral component of in the multidisciplinary management of cancer patients. Intensive inquiry in this area is likely to increase further over the next decade; however, cancer-specific, evidence-based risk assessment and recommendations for physical activity are not available. A systematic literature review was performed of all studies conducting an exercise training intervention and (or) any form of objective exercise test among adults diagnosed with cancer. Studies were assessed according to evaluation criteria developed by a panel of experts. A total of 118 studies involving 5529 patients were deemed eligible. Overall, the results suggest that exercise training and maximal and submaximal exercise testing are relatively safe procedures with a total nonlife-threatening adverse event rate of <2%. There was only 1 exercise training-related death. However, the quality of exercise testing methodology and data reporting is less than optimal. Thus, whether the low incidence of events reflects the true safety of exercise training and exercise testing in cancer patients or less than optimal methodology and (or) data reporting remains to be determined. Evidence-based absolute and relative contraindications to physical activity and exercise training and testing are provided as well as probing decision-trees to optimize the adoption and safety of physical activity in persons diagnosed with cancer.

ZIP4 is a novel molecular marker for glioma

BACKGROUND

Dysregulated zinc transport has been observed in many cancers. However, the status of zinc homeostasis and the expression profile of zinc transporters in brain and brain tumors have not been reported.

METHODS

The gene profiles of 14 zinc importers (ZIPs) and 10 zinc exporters (ZnTs) in patients with glioma were studied by investigating the association between the zinc transporters and brain tumor characteristics (tumor grade and overall survival time). Three independent cohorts were analyzed to cross-validate the findings: the Chinese Glioma Genome Atlas (CGCA) cohort (n = 186), the US National Cancer Institute Repository for Molecular Brain Neoplasia Data (REMBRANDT) cohort (n = 335), and The University of Texas (UT) cohort (n = 34).

RESULTS

The expression of ZIP3, 4, 8, 14, ZnT5, 6, and 7 were increased, and the expression of ZnT10 was decreased in grade IV gliomas, compared with grade II gliomas. Among all 24 zinc transporters, ZIP4 is most significantly associated with tumor grade and overall survival; this finding is consistent across 2 independent cohorts (CGCA and REMBRANDT) and is partially validated by the third cohort (UT). High ZIP4 expression was significantly associated with higher grade of gliomas and shorter overall survival (hazard ratio = 1.61, 95% confidence interval = 1.02-2.53, P = .040 in CGCA cohort; hazard ratio = 1.32, 95% confidence interval = 1.08-1.61, P = .007 in REMBRANDT cohort).

CONCLUSIONS

Dysregulated expression of zinc transporters is involved in the progression of gliomas. Our results suggest that ZIP4 may serve as a potential diagnostic and prognostic marker for gliomas.

Tumor-targeting and microenvironment-responsive smart nanoparticles for combination therapy of antiangiogenesis and apoptosis

Tumor microenvironment, such as the lowered tumor extracellular pH (pHe) and matrix metalloproteinase 2 (MMP2), has been extensively explored, which promotes the development of the microenvironment-responsive drug delivery system. Utilizing these unique features, an activatable cell-penetrating peptide (designated as dtACPP) that is dual-triggered by the lowered pHe and MMP2 has been constructed, and a smart nanoparticle system decorating with dtACPP has been successfully developed, which could dual-load gene drug and chemotherapeutics simultaneously. After systemic administration, dtACPP-modified nanoparticles possess passive tumor targetability via the enhanced permeability and retention effect. Then dtACPP would be activated to expose cell-penetrating peptide to drive the nanoparticles' internalization into the intratumoral cells. As angiogenesis and tumor cells might be mutually improved in tumor growth, so combining antiangiogenesis and apoptosis is meaningful for oncotherapy. Vascular endothelial growth factor (VEGF) is significant in angiogenesis, and anti-VEGF therapy could decrease blood vessel density and delay tumor growth obviously. Chemotherapy using doxorubicin (DOX) could kill off tumor cells efficiently. Here, utilizing dtACPP-modified nanoparticles to co-deliver plasmid expressing interfering RNA targeting VEGF (shVEGF) and DOX (designated as dtACPPD/shVEGF-DOX) results in effective shutdown of blood vessels and cell apoptosis within the tumor. On the premise of effective drug delivery, dtACPPD/shVEGF-DOX has demonstrated good tumor targetability, little side effects after systemic administration, and ideal antitumor efficacy.

Oncogene interactions are required for glioma development and progression as revealed by a tissue specific transgenic mouse model

The aggressive and invasive nature of brain tumors has hampered progress in the design and implementation of efficacious therapies. The recent success of targeted therapies in other tumor types makes this an attractive area for research yet complicating matters is the ability of brain tumors to circumvent the targeted pathways to develop drug resistance. Effective therapies will likely need to target more than one signaling pathway or target multiple nodes within a given pathway. Key to identifying these targets is the elucidation of the driver and passenger molecules within these pathways. Animal models provide a useful tool with many advantages in the study of these pathways. These models provide a means to dissect the critical components of tumorigenesis, as well as serve as agents for preclinical testing. This review focuses on the use of the RCAS/tv-a mouse model of brain tumors and describes their unique ability to provide insight into the role of Oncogene cooperation in tumor development and progression.

Vascular-targeted photothermal therapy of an orthotopic murine glioma model

AIM

To develop nanoshells for vascular-targeted photothermal therapy of glioma.

MATERIALS & METHODS

The ability of nanoshells conjugated to VEGF and/or poly(ethylene glycol) (PEG) to thermally ablate VEGF receptor-2-positive endothelial cells upon near-infrared laser irradiation was evaluated in vitro. Subsequent in vivo studies evaluated therapy in mice bearing intracerebral glioma tumors by exposing tumors to near-infrared light after systemically delivering saline, PEG-coated nanoshells, or VEGF-coated nanoshells. The treatment effect was monitored with intravital microscopy and histology.

RESULTS

VEGF-coated but not PEG-coated nanoshells bound VEGF receptor-2-positive cells in vitro to enable targeted photothermal ablation. In vivo, VEGF targeting doubled the proportion of nanoshells bound to tumor vessels and vasculature was disrupted following laser exposure. Vessels were not disrupted in mice that received saline. The normal brain was unharmed in all treatment and control mice.

CONCLUSION

Nanoshell therapy can induce vascular disruption in glioma.

Recent developments on immunotherapy for brain cancer

INTRODUCTION

Brain tumors are a unique class of cancers since they are anatomically shielded from normal immunosurveillance by the blood-brain barrier, lack a normal lymphatic drainage system and reside in a potently immunosuppressive environment. Of the primary brain cancers, glioblastoma multiforme (GBM) is the most common and aggressive in adults. Although treatment options include surgery, radiation and chemotherapy, the average lifespan of GBM patients remains at only 14.6 months post-diagnosis.

AREAS COVERED

A review of key cellular and molecular immune system mediators in the context of brain tumors including TGF-β, cytotoxic T cells, Tregs, CTLA-4, PD-1 and IDO is discussed. In addition, prognostic factors, currently utilized immunotherapeutic strategies, ongoing clinical trials and a discussion of new or potential immunotherapies for brain tumor patients are considered.

EXPERT OPINION

Current drugs that improve the quality of life and overall survival in patients with brain tumors, especially for GBM, are poorly effective. This disease requires a reanalysis of currently accepted treatment strategies, as well as newly designed approaches. Here, we review the fundamental aspects of immunosuppression in brain tumors, new and promising immunotherapeutic drugs as well as combinatorial strategies that focus on the simultaneous inhibition of immunosuppressive hubs, both in immune and brain tumor cells, which is critical to consider for achieving future success for the treatment of this devastating disease.

Immunotherapy targeting glioma stem cells--insights and perspectives

INTRODUCTION

Glioblastoma multiforme (GBM) is the most aggressive and lethal primary malignant brain tumor. Although progress has been made in current conventional therapies for GBM patients, the effect of these advances on clinical outcomes has been disappointing. Recent research into the origin of cancers suggest that GBM cancer stem cells (GSC) are the source of initial tumor formation, resistance to current conventional therapeutics and eventual patient relapse. Currently, there are very few studies that apply immunotherapy to target GSC.

AREAS COVERED

CD133, a cell surface protein, is used extensively as a surface marker to identify and isolate GSC in malignant glioma. We discuss biomarkers such as CD133, L1-cell adhesion molecule (L1-CAM), and A20 of GSC. We review developing novel treatment modalities, including immunotherapy strategies, to target GSC.

EXPERT OPINION

There are very few reports of preclinical studies targeting GSC. Identification and validation of unique molecular signatures and elucidation of signaling pathways involved in survival, proliferation and differentiation of GSC will significantly advance this field and provide a framework for the rational design of a new generation of antigen-specific, anti-GSC immunotherapy- and nanotechnology-based targeted therapyies. Combined with other therapeutic avenues, GSC-targeting therapies may represent a new paradigm to treat GBM patients.

Salvage therapy with single agent bendamustine for recurrent glioblastoma

The treatment of recurrent glioblastoma (GBM) remains challenging notwithstanding the recent approval of bevacizumab for this indication. Bendamustine has a bifunctional mechanism of action including alkylation, penetrates the CNS and does not show cross resistance to other alkylator chemotherapies. In a single institution phase 2 trial, patients with recurrent GBM were treated with bendamustine (100 mg/m(2)/day administered intravenously for two consecutive days every 4 weeks). The primary study endpoint was 6-month progression free survival (PFS-6). An interim analysis for futility was conducted according to a Simon two-stage minimax design. Complete blood counts were obtained bimonthly, clinical evaluations and brain imaging every month for the first cycle and bimonthly thereafter. Treatment responses were based upon MacDonald criteria. Sixteen patients were enrolled (nine men; seven women), with a median age of 53 years (range 36-68) and a median Karnofsky performance status of 90 (range 70-100). Nine patients were treated at first relapse and seven at second relapse (five patients were bevacizumab failures). A total of 25 cycles of bendamustine were administered with a median of 1 (range 1-6). Bendamustine-related toxicity was seen in eight patients; lymphopenia in seven (5 grade 3; 2 Grade 4), thrombocytopenia in two (1 Grade 3; 1 Grade 4), and neutropenia in one (1 Grade 3). Fourteen patients have died due to disease progression, two patients are alive and on alternative therapies. Only one patient was progression-free at 6 months, triggering the stopping rule for futility. Bendamustine was reasonably well tolerated but failed to meet the study criteria for activity in adults with recurrent GBM.

Bevacizumab for the treatment of recurrent glioblastoma

Despite advances in upfront therapy, the prognosis in the great majority of patients with glioblastoma (GBM) is poor as almost all recur and result in disease-related death. Glioblastoma are highly vascularized cancers with elevated expression levels of vascular endothelial growth factor (VEGF), the dominant mediator of angiogenesis. A compelling biologic rationale, a need for improved therapy, and positive results from studies of bevacizumab in other cancers led to the evaluation of bevacizumab in the treatment of recurrent GBM. Bevacizumab, a humanized monoclonal antibody that targets VEGF, has been shown to improve patient outcomes in combination with chemotherapy (most commonly irinotecan) in recurrent GBM, and on the basis of positive results in two prospective phase 2 studies, bevacizumab was granted accelerated approval by the US Food and Drug Administration (FDA) as a single agent in recurrent GBM. Bevacizumab therapy is associated with manageable, class-specific toxicity as severe treatment-related adverse events are observed in only a minority of patients. With the goal of addressing questions and controversies regarding the optimal use of bevacizumab, the objective of this review is to provide a summary of the clinical efficacy and safety data of bevacizumab in patients with recurrent GBM, the practical issues surrounding the administration of bevacizumab, and ongoing investigations of bevacizumab in managing GBM.

Hedgehog/GLI1 regulates IGF dependent malignant behaviors in glioma stem cells

A population of tumorigenic, chemoresistant, and radioresistant cancer stem cells is postulated to contribute to the aggressive and fatal clinical course of glioblastomas. Activation of the Hedgehog (HH) pathway and increased expression of its downstream effector GLI1 are driving factors of glioma tumorigenicity and glioma stem cell (GSC) biology. In this study, we describe a dependence of insulin-like growth factor (IGF) signaling on active HH/GLI1 in GSCs. Insulin receptor substrate 1 (IRS1) was identified as a target of the GLI1 transcription factor and inhibition of GLI1 was sufficient to obstruct IRS1 protein expression and IGF-I induced mitogen-activated protein kinase (MAPK) activation. Suppression of GLI1 activity decreased the responsiveness of GSCs to IGF-I stimulation and constrained IGF-I dependent GSC proliferation, clonogenicity, invasion, and angiogenesis. In addition, blockade of the HH/GLI1 and IGF pathways countered the intrinsic and acquired resistance of GSCs to temozolomide. These results provide further insight into the oncogenic mechanisms of the HH pathway in glioblastoma and demonstrate a cooperative signaling axis between the HH/GLI1 and IGF pathways to propagate malignant GSC phenotypes.

Anti-VEGF treatment reduces blood supply and increases tumor cell invasion in glioblastoma

Bevacizumab, an antibody against vascular endothelial growth factor (VEGF), is a promising, yet controversial, drug in human glioblastoma treatment (GBM). Its effects on tumor burden, recurrence, and vascular physiology are unclear. We therefore determined the tumor response to bevacizumab at the phenotypic, physiological, and molecular level in a clinically relevant intracranial GBM xenograft model derived from patient tumor spheroids. Using anatomical and physiological magnetic resonance imaging (MRI), we show that bevacizumab causes a strong decrease in contrast enhancement while having only a marginal effect on tumor growth. Interestingly, dynamic contrast-enhanced MRI revealed a significant reduction of the vascular supply, as evidenced by a decrease in intratumoral blood flow and volume and, at the morphological level, by a strong reduction of large- and medium-sized blood vessels. Electron microscopy revealed fewer mitochondria in the treated tumor cells. Importantly, this was accompanied by a 68% increase in infiltrating tumor cells in the brain parenchyma. At the molecular level we observed an increase in lactate and alanine metabolites, together with an induction of hypoxia-inducible factor 1α and an activation of the phosphatidyl-inositol-3-kinase pathway. These data strongly suggest that vascular remodeling induced by anti-VEGF treatment leads to a more hypoxic tumor microenvironment. This favors a metabolic change in the tumor cells toward glycolysis, which leads to enhanced tumor cell invasion into the normal brain. The present work underlines the need to combine anti-angiogenic treatment in GBMs with drugs targeting specific signaling or metabolic pathways linked to the glycolytic phenotype.

Targeting miR-21 in glioma: a small RNA with big potential

IMPORTANCE OF THE FIELD

Glioma therapies have produced relatively small improvements over the past decade, highlighting an important need to identify novel ways to target this disease. Targeted therapies against single activated protein kinases have proven effective in some cancers including gastrointestinal stromal cancer and colon cancer, but not yet in gliomas where multiple pathways and targets may be involved. MicroRNAs are emerging as key regulators of multiple pathways involved in cancer development and progression and may become the next targeted therapies in glioma.

AREAS COVERED IN THIS REVIEW

This review covers the basics of microRNA biology and specifically focuses on the roles of miR-21 in glioma and its potential as target for glioma therapy.

WHAT THE READER WILL GAIN

This review will provide the reader with an in depth understanding of how miR-21 functions in glioma. We also review the current state of studies designed to specifically target miR-21 as a potential future therapeutic.

TAKE HOME MESSAGE

Identifying novel targets for the treatment of glioma is critical for advancing the current state of the field. MicroRNAs provide a novel target; and in glioma, targeting miR-21 may have broad consequences for the tumor that make it an attractive potential therapeutic.

Characterization of a human tumorsphere glioma orthotopic model using magnetic resonance imaging

Magnetic resonance imaging (MRI) is the imaging modality of choice by which to monitor patient gliomas and treatment effects, and has been applied to murine models of glioma. However, a major obstacle to the development of effective glioma therapeutics has been that widely used animal models of glioma have not accurately recapitulated the morphological heterogeneity and invasive nature of this very lethal human cancer. This deficiency is being alleviated somewhat as more representative models are being developed, but there is still a clear need for relevant yet practical models that are well-characterized in terms of their MRI features. Hence we sought to chronicle the MRI profile of a recently developed, comparatively straightforward human tumor stem cell (hTSC) derived glioma model in mice using conventional MRI methods. This model reproduces the salient features of gliomas in humans, including florid neoangiogenesis and aggressive invasion of normal brain. Accordingly, the variable, invasive morphology of hTSC gliomas visualized on MRI duplicated that seen in patients, and it differed considerably from the widely used U87 glioma model that does not invade normal brain. After several weeks of tumor growth the hTSC model exhibited an MRI contrast enhancing phenotype having variable intensity and an irregular shape, which mimicked the heterogeneous appearance observed with human glioma patients. The MRI findings reported here support the use of the hTSC glioma xenograft model combined with MRI, as a test platform for assessing candidate therapeutics for glioma, and for developing novel MR methods.

Emerging clinical principles on the use of bevacizumab for the treatment of malignant gliomas

Despite advances in adjuvant therapy, the prognosis for most patients with high-grade glioma (HGG) is poor, and almost all HGGs have a likelihood of disease recurrence. HGGs are highly vascularized tumors with elevated expression levels of vascular endothelial growth factor (VEGF), an important mediator of angiogenesis. A compelling biologic rationale, a pressing need for improved therapeutics and positive results from studies of bevacizumab in other tumor types, led to the evaluation of bevacizumab in the treatment of HGG. It was demonstrated previously that bevacizumab, which is a humanized monoclonal antibody that targets VEGF, improved outcomes when combined with chemotherapy (most commonly irinotecan) in patients with recurrent HGG; and, on the basis of an improved objective response rate in 2 prospective phase 2 studies, bevacizumab was granted accelerated approval by the US Food and Drug Administration as a single agent in patients with previously treated glioblastoma (GB). Bevacizumab-containing therapy has been associated with manageable, class-specific toxicity; however, severe treatment-related adverse events are observed in a minority of patients. Preliminary data on bevacizumab-based therapy in recurrent anaplastic gliomas, in the frontline treatment of GB, and in additional patient populations are also encouraging. With the goal of addressing unanswered questions regarding the optimal use of bevacizumab, the objective of the current review was to provide a summary of the clinical efficacy and safety data on bevacizumab in patients with HGG, the practical issues surrounding the administration of bevacizumab, and ongoing investigations of bevacizumab in additional brain tumor treatment settings.

Glioma proteomics: status and perspectives

High grade gliomas are the most common brain tumors in adults and their malignant nature makes them the fourth biggest cause of cancer death. Major efforts in neuro-oncology research are needed to reach similar progress in treatment efficacy as that achieved for other cancers in recent years. In addition to the urgent need to identify novel effective drug targets against malignant gliomas, the search for glioma biomarkers and grade specific protein signatures will provide a much needed contribution to diagnosis, prognosis, treatment decision and assessment of treatment response. Over the past years glioma proteomics has been attempted at different levels, including proteome analysis of patient biopsies and bodily fluids, of glioma cell lines and animal models. Here we provide an extensive review of the outcome of these studies in terms of protein identifications (protein numbers and regulated proteins), with an emphasis on the methods used and the limitations of the studies with regard to biomarker discovery. This is followed by a perspective on novel technologies and on the potential future contribution of proteomics in a broad sense to understanding glioma biology.

Quantitative assessment of cardiorespiratory fitness, skeletal muscle function, and body composition in adults with primary malignant glioma

BACKGROUND

The study was undertaken to evaluate cardiorespiratory fitness, skeletal muscle function, and body composition of patients with newly diagnosed and untreated, postsurgical primary malignant glioma.

METHODS

By using a cross-sectional design, patients with clinically stable (10 +/- 7 days postsurgery) high-grade glioma (HGG; n = 25) or low-grade glioma (LGG; n = 10) were studied. Participants performed a cardiopulmonary exercise test (CPET) with expired gas analysis to assess cardiorespiratory fitness (peak oxygen consumption, VO2peak). Other physiological outcomes included skeletal muscle cross-sectional area (CSA; magnetic resonance imaging), isokinetic muscle strength (isokinetic dynamometer), and body composition (air displacement plethysmography). Quality of life was assessed with the Functional Assessment of Cancer Therapy-Brain scale.

RESULTS

CPET was a feasible and safe procedure to assess VO2peak, with no serious adverse events. VO2peak indexed to total body weight and lean body mass (LBM) for both groups was 13.0 mL x weight x min(-1) and 19 mL x LBM x min(-1), the equivalent to 59% and 38% below age- and sex-predicted normative values, respectively. Skeletal muscle strength and mid-thigh CSA were lower in HGG relative to LGG patients (83 vs 125 Nm, P = .025; 94 vs 119 cm2, P = .171, respectively). Skeletal muscle isokinetic strength, CSA, and body composition outcomes predicted VO2peak (r = -0.59 to 0.68, P < .05).

CONCLUSIONS

Postsurgical glioma patients have markedly reduced cardiorespiratory fitness, isokinetic strength, and CSA. Prospective studies are now required to determine whether such abnormalities influence treatment toxicity and clinical outcome as well as to test the effect of appropriately selected interventions to prevent and/or mitigate dysfunction.

Phase I study of vandetanib with radiotherapy and temozolomide for newly diagnosed glioblastoma

PURPOSE

Increasing evidence has suggested that angiogenesis inhibition might potentiate the effects of radiotherapy and chemotherapy in patients with glioblastoma (GBM). In addition, epidermal growth factor receptor inhibition might be of therapeutic benefit, because the epidermal growth factor receptor is upregulated in GBM and contributes to radiation resistance. We conducted a Phase I study of vandetanib, an inhibitor of vascular endothelial growth factor receptor 2 and epidermal growth factor receptor, in patients with newly diagnosed GBM combined with RT and temozolomide (TMZ).

METHODS AND MATERIALS

A total of 13 GBM patients were treated with vandetanib, radiotherapy, and concurrent and adjuvant TMZ, using a standard "3 + 3" dose escalation. The maximal tolerated dose was defined as the dose with <1 of 6 dose-limiting toxicities during the first 12 weeks of therapy. The eligible patients were adults with newly diagnosed GBM, Karnofsky performance status of >or=60, normal organ function, who were not taking enzyme-inducing antiepileptic drugs.

RESULTS

Of the 13 patients, 6 were treated with vandetanib at a dose of 200mg daily. Of the 6 patients, 3 developed dose-limiting toxicities within the first 12 weeks, including gastrointestinal hemorrhage and thrombocytopenia in 1 patient, neutropenia in 1 patient, and diverticulitis with gastrointestinal perforation in 1 patient. The other 7 patients were treated with 100 mg daily, with no dose-limiting toxicities observed, establishing this dose as the maximal tolerated dose combined with TMZ and RT.

CONCLUSION

Vandetanib can be safely combined with RT and TMZ in GBM patients. A Phase II study in which patients are randomized to vandetanib 100 mg daily with RT and TMZ or RT and TMZ alone is underway.

XL-184, a MET, VEGFR-2 and RET kinase inhibitor for the treatment of thyroid cancer, glioblastoma multiforme and NSCLC

XL-184 (BMS-907351), under development by Exelixis Inc and Bristol-Myers Squibb Co, is a pan-tyrosine kinase inhibitor for the potential oral treatment of medullary thyroid cancer, glioblastoma multiforme and NSCLC. The prinicipal targets of XL-184 are MET, VEGFR-2 and RET, but the drug is also reported to display inhibitory activity against KIT, FLT3 and TEK. Preclinical studies demonstrated that XL-184 potently inhibited multiple receptor tyrosine kinases in various cancer cell lines and animal xenograft models, and that the drug exhibited significant oral bioavailability and blood-brain barrier penetration. A phase I clinical trial in patients with advanced solid malignancies indicated that XL-184 accumulated dose-dependently in the plasma and had a long terminal half-life. A phase II trial in patients with progressive or recurrent glioblastoma revealed modest but promising median progression-free survival. Toxicity and side effects for the drug have generally been of low-to-moderate severity. At the time of publication, three additional trials of XL-184 were recruiting patients, including a phase I trial in combination with standard of care in patients with glioblastoma, a phase I/II trial in combination with erlotinib in patients with NSCLC, and a phase III trial in patients with medullary thyroid cancer.