Accelerated radiotherapy, carbogen, and nicotinamide in glioblastoma multiforme: report of European Organization for Research and Treatment of Cancer trial 22933

Functional impact of oxygen-saturated zeolite nanoparticles on macrophages in the context of glioblastoma: an in vitro and in vivo study

In the context of glioblastoma (GBM), hypoxia and inflammation are two main players of the tumor microenvironment. Hypoxia stimulates various features involves in tumor growth and also maintains a specific environment that favors protumor macrophages. Therefore, targeting hypoxia could potentially restore an anti-tumor M1 phenotype in macrophages. Besides, iron demonstrated its capacity to stimulate the polarization of macrophages towards an M1-like phenotype. In this paper we took advantages of microporous nanoparticles to co-deliver both oxygen and iron to bone marrow derived macrophages (BMDM) enabling the investigation of changes in polarization status and proteomic profiles. The nanoparticles were used in two in vivo models of glioblastoma, specifically, in both immunodeficient and immunocompetent settings. Our in vitro findings revealed that iron doped nanoparticles, saturated with oxygen were deemed safe for macrophages but did not demonstrate the capacity to change the M1 or M2 phenotypes. However, these nanoparticles induced some changes in proteomics pathways. The present study reports on in vivo experimentation that revealed the effects of nanoparticles on the hypoxic fraction, tumor volume, and macrophage phenotype in a GBM model. The findings indicated that the presence of nanoparticles led to a reduction in the hypoxic fraction in one of the GBM models, while no significant changes were observed in the tumor volume or macrophage phenotype. The present data showed that nanoparticles possess the capability of delivering both oxygen and iron to macrophages; though, they do not possess the ability to effectively repolarize M2 macrophages. Such strategies could be used in conjunction with other potent molecules to avoid M1 macrophages to inevitably differentiate to M2 macrophages.

The use of radiosensitizing agents in the therapy of glioblastoma multiforme-a comprehensive review

BACKGROUND

Glioblastoma is the most common malignant brain tumor in human adults. Despite several improvements in resective as well as adjuvant therapy over the last decades, its overall prognosis remains poor. As a means of improving patient outcome, the possibility of enhancing radiation response by using radiosensitizing agents has been tested in an array of studies.

METHODS

A comprehensive review of clinical trials involving radiation therapy in combination with radiosensitizing agents on patients diagnosed with glioblastoma was performed in the National Center for Biotechnology Information's PubMed database.

RESULTS

A total of 96 papers addressing this matter were published between 1976 and 2021, of which 63 matched the subject of this paper. All papers were reviewed, and their findings discussed in the context of their underlining mechanisms of radiosensitization.

CONCLUSION

In the history of glioblastoma treatment, several approaches of optimizing radiation-effectiveness using radiosensitizers have been made. Even though several different strategies and agents have been explored, clear evidence of improved patient outcome is still missing. Tissue-selectiveness and penetration of the blood-brain barrier seem to be major roadblocks; nevertheless, modern strategies try to circumvent these obstacles, using novel sensitizers based on preclinical data or alternative ways of delivery.

Current Landscape and Future Prospects of Radiation Sensitizers for Malignant Brain Tumors: A Systematic Review

BACKGROUND

Radiation therapy (RT) is the cornerstone of management of malignant brain tumors, but its efficacy is limited in hypoxic tumors. Although numerous radiosensitizer compounds have been developed to enhance the effect of RT, progress has been stagnant. Through this systematic review, we provide an overview of radiosensitizers developed for malignant brain tumors, summarize their safety and efficacy, and evaluate areas for possible improvement.

METHODS

Following PRISMA guidelines, PubMed, EMBASE, Cochrane, and Web of Science were searched using terminology pertaining to radiosensitizers for brain tumor RT. Articles reporting clinical evidence of nonantineoplastic radiosensitizers with RT for malignant central nervous system tumors were included. Data of interest were presumed mechanism of action, median overall survival (OS), progression-free survival (PFS), and adverse events.

RESULTS

Twenty-two unique radiosensitizers were identified. Only 2/22 agents (fluosol with oxygen, and efaproxiral) showed improvement in OS in patients with glioblastoma and brain metastasis, respectively. A larger study was not able to confirm the latter. Improved PFS was reported with use of metronidazole, sodium glycididazole, and chloroquine. There was a wide range of toxicities, which prompted change of schedule or complete discontinuation of 9 agents.

CONCLUSIONS

Progress in radiosensitizers for malignant CNS tumors has been limited. Only 2 radiosensitizers have shown limited improvement in survival. Alternative strategies such as synthetic drug design, based on a mechanism of action that is independent of crossing the blood-brain barrier, may be necessary. Use of drug development strategies using new technologies to overcome past challenges is necessary.

Complementary and Alternative Medicine for the Treatment of Gliomas: Scoping Review of Clinical Studies, Patient Outcomes, and Toxicity Profiles

INTRODUCTION

Complementary and alternative medicine (CAM) are highly used among those diagnosed with glioma. Further research is warranted, however, as it remains important to clearly delineate CAM practices that are unproven, disproven, or promising for future research and implementation.

METHODS

A systematic review was conducted to identify all articles that investigated the effect of any CAM therapy on survival of patients with newly diagnosed or recurrent glioma.

RESULTS

Eighteen papers and 4 abstracts pertaining to the effects of ketogenic diet (4), antioxidants (3), hyperbaric oxygen (4), cannabinoids (2), carbogen and nicotinamide (3), mistletoe extract (2), hypocupremia and penicillamine (1), and overall CAM use (3) on overall and progression-free survival in patients with low- and high-grade glioma were identified (Levels of Evidence I-IV). Ketogenic diets, hyperbaric oxygen therapy, and cannabinoids appear to be safe and well tolerated by patients; preliminary studies demonstrate tumor response and increased progression-free survival and overall survival when combined with standard of care therapies. Antioxidant usage exhibit mixed results perhaps associated with glioma grade with greater effect on low-grade gliomas; vitamin D intake was associated with prolonged survival. Conversely, carbogen breathing and hypocupremia were found to have no effect on the survival of patients with glioma, with associated significant toxicity. Most modalities under the CAM umbrella have not been appropriately studied and require further investigation.

CONCLUSIONS

Despite widespread use, Level I or II evidence for CAM for the treatment of glioma is lacking, representing future research directions to optimally counsel and treat glioma patients.

The Role of 2-Oxoglutarate Dependent Dioxygenases in Gliomas and Glioblastomas: A Review of Epigenetic Reprogramming and Hypoxic Response

Gliomas are a heterogeneous group of cancers that predominantly arise from glial cells in the brain, but may also arise from neural stem cells, encompassing low-grade glioma and high-grade glioblastoma. Whereas better diagnosis and new treatments have improved patient survival for many cancers, glioblastomas remain challenging with a highly unfavorable prognosis. This review discusses a super-family of enzymes, the 2-oxoglutarate dependent dioxygenase enzymes (2-OGDD) that control numerous processes including epigenetic modifications and oxygen sensing, and considers their many roles in the pathology of gliomas. We specifically describe in more detail the DNA and histone demethylases, and the hypoxia-inducible factor hydroxylases in the context of glioma, and discuss the substrate and cofactor requirements of the 2-OGDD enzymes. Better understanding of how these enzymes contribute to gliomas could lead to the development of new treatment strategies.

One-Year Outcome of Multiple Blood-Brain Barrier Disruptions With Temozolomide for the Treatment of Glioblastoma

Introduction: To overcome the blood-brain barrier (BBB) which interferes with the effect of chemotherapeutic agents, we performed multiple disruptions of BBB (BBBD) with magnetic resonance-guided focused ultrasound on patients with glioblastoma (GBM) during standard adjuvant temozolomide (TMZ) chemotherapy [clinical trial registration no.NCT03712293 (clinicaltrials.gov)]. We report a 1-year follow-up result of BBBD with TMZ for GBM. Methods: From September 2018 to January 2019, six patients were enrolled (four men and two women, median age: 53 years, range: 50-67 years). Of the six patients, five underwent a total of six cycles of BBBD during standard TMZ adjuvant therapy. One patient underwent three cycles of BBBD but continued with TMZ chemotherapy. The 1-year follow-up results of these six patients were reviewed. Results: The mean follow-up duration was 15.17 ± 1.72 months. Two patients showed a recurrence of tumor at 11 and 16 months, respectively. One underwent surgery, and the other patient was restarted with TMZ chemotherapy due to the tumor location with a highly possibility of surgical complications. The survival rate up to 1 year was 100%, and the other four patients are on observation without recurrence. None of the six patients had immediate or delayed BBBD-related complications. Conclusion: Multiple BBBDs can be regarded as a safe procedure without long-term complications, and it seems to have some survival benefits. However, since TMZ partially crosses the BBB, a further extended study with large numbers would be needed to evaluate the benefits of BBBD resulting in an increase of TMZ concentration. This study opened a new therapeutic strategy for GBM by combining BBBD with a larger molecular agent.

The Role of Nicotinamide in Cancer Chemoprevention and Therapy

Nicotinamide (NAM) is a water-soluble form of Vitamin B3 (niacin) and a precursor of nicotinamide-adenine dinucleotide (NAD⁺) which regulates cellular energy metabolism. Except for its role in the production of adenosine triphosphate (ATP), NAD⁺ acts as a substrate for several enzymes including sirtuin 1 (SIRT1) and poly ADP-ribose polymerase 1 (PARP1). Notably, NAM is an inhibitor of both SIRT1 and PARP1. Accumulating evidence suggests that NAM plays a role in cancer prevention and therapy. Phase III clinical trials have confirmed its clinical efficacy for non-melanoma skin cancer chemoprevention or as an adjunct to radiotherapy against head and neck, laryngeal, and urinary bladder cancers. Evidence for other cancers has mostly been collected through preclinical research and, in its majority, is not yet evidence-based. NAM has potential as a safe, well-tolerated, and cost-effective agent to be used in cancer chemoprevention and therapy. However, more preclinical studies and clinical trials are needed to fully unravel its value.

Clinical trials targeting hypoxia

The concept of tumour hypoxia as a cause of radiation resistance has been prevalent for over 100 years. During this time, our understanding of tumour hypoxia has matured with the recognition that oxygen tension within a tumour is influenced by both diffusion and perfusion mechanisms. In parallel, clinical strategies to modify tumour hypoxia with the expectation that this will improve response to radiation have been developed and tested in clinical trials. Despite many disappointments, meta-analysis of the data on hypoxia modification confirms a significant impact on both tumour control and survival. Early trials evaluated hyperbaric oxygen followed by a generation of studies testing oxygen mimetics such as misonidazole, pimonidazole and etanidazole. One highly significant result stands out from the use of nimorazole in advanced laryngeal cancer with a significant advantage seen for locoregional control using this radiosensitiser. More recent studies have evaluated carbogen and nicotinamide targeting both diffusion related and perfusion related hypoxia. A significant survival advantage is seen in muscle invasive bladder cancer and also for locoregional control in hypopharygeal cancer associated with a low haemoglobin. New developments include the recognition that mitochondrial complex inhibitors reducing tumour oxygen consumption are potential radiosensitising agents and atovaquone is currently in clinical trials. One shortcoming of past hypoxia modifying trials is the failure to identify oxygenation status and select those patient with significant hypoxia. A range of biomarkers are now available including histological necrosis, immunohistochemical intrinsic markers such as CAIX and Glut 1 and hypoxia gene signatures which have been shown to predict outcome and will inform the next generation of hypoxia modifying clinical trials.

Radiation combined with temozolomide contraindicated for young adults diagnosed with anaplastic glioma

Purpose

Age is a major prognostic factor for malignant gliomas. However, few studies have investigated the management of gliomas in young adults. We determined the role of survival and treatment in young adults with advanced gliomas in a large population from the Chinese Glioma Genome Atlas (CGGA).

Methods

This study included 726 adults (age ≥ 18) with histologically proven anaplastic glioma or glioblastoma multiforme (GBM). The overall and progression-free survival was determined in young (age < 50) and older groups (age ≥ 50).

Results

The study included an older group (OP) of 264 patients and a younger group (YP) of 462patients. In the OP group with GBM and anaplastic glioma, patients treated with RT combined with temozolomide (TMZ) manifested significantly longer OS and PFS compared with patients assigned to RT alone (P < 0.05). In contrast, the YP group diagnosed with anaplastic glioma failed to show any survival advantage with RT plus TMZ compared with RT alone.

Conclusions

We observed no survival benefit in young adults (age < 50) with anaplastic glioma when treated with TMZ combined with RT. Our findings warrant further investigation of younger patients diagnosed with anaplastic glioma treated with radiotherapy plus TMZ chemotherapy.

Evaluation of tumour vascular distribution and function using immunohistochemistry and BOLD fMRI with carbogen inhalation

AIM

To evaluate oxygenation changes in rat subcutaneous C6 gliomas using blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) combined with non-haemodynamic response function (non-HRF) analysis.

MATERIALS AND METHODS

BOLD fMRI were performed during carbogen inhalation in 20 Wistar rats bearing gliomas. Statistical maps of spatial oxygenation changes were computed by a dedicated non-HRF analysis algorithm. Three types of regions of interest (ROIs) were defined: (1) maximum re-oxygenation zone (ROI_max), (2) re-oxygenation zones that were less than the maximum re-oxygenation (ROI_non-max), and (3) zones without significant re-oxygenation (ROI_none). The values of percent BOLD signal change (PSC), percent enhancement (ΔSI), and significant re-oxygenation (T) were extracted from each ROI. Tumours were sectioned for histology using the fMRI scan orientation and were stained with haematoxylin and eosin and CD105. The number of microvessels (MVN) in each ROI was counted. Differences and correlations among the values for T, PSC, ΔSI, and MVN were determined.

RESULTS

After carbogen inhalation, the PSC significantly increased in the ROI_max areas (p<0.01) located in the tumour parenchyma. No changes occurred in any of the ROI_none areas (20/20). Some changes occurred in a minority of the ROI_non-max areas (3/60) corresponding to tumour necrosis. MVN and PSC (R=0.59, p=0.01) were significantly correlated in the ROI_max areas. In the ROI_non-max areas, MVN was significantly correlated with PSC (R=0.55, p=0.00) and ΔSI (R=0.37, p=0.00).

CONCLUSIONS

Statistical maps obtained via BOLD fMRI with non-HRF analysis can assess the re-oxygenation of gliomas.

Concurrent therapy to enhance radiotherapeutic outcomes in glioblastoma

Glioblastoma is one of the most fatal and incurable human cancers characterized by nuclear atypia, mitotic activity, intense microvascular proliferation and necrosis. The current standard of care includes maximal safe surgical resection followed by radiation therapy (RT) with concurrent and adjuvant temozolomide (TMZ). The prognosis remains poor with median survival of 14.6 months with RT plus TMZ. Majority will have a recurrence within 2 years from diagnosis despite adequate treatment. Radiosensitizers, radiotherapy dose escalation and altered fractionation have failed to improve outcome. The molecular biology of glioblastoma is complex and poses treatment challenges. High rate of mutation, genotypic and phenotypic heterogeneity, rapid development of resistance, existence of blood-brain barrier (BBB), multiple intracellular and intercellular signalling pathways, over-expression of growth factor receptors, angiogenesis and antigenic diversity renders the tumor cells differentially susceptible to various treatment modalities. Thus, the treatment strategies require personalised or individualized approach based on the characteristics of tumor. Several targeted agents have been evaluated in clinical trials but the results have been modest despite these advancements. This review summarizes the current standard of care, results of concurrent chemoradiation trials, evolving innovative treatments that use targeted therapy with standard chemoradiation or RT alone, outcome of various recent trials and future outlook.

Early treatment of HER2-amplified brain tumors with targeted NK-92 cells and focused ultrasound improves survival

BACKGROUND

Malignant brain tumors have a dismal prognosis, with residual tumor remaining after surgery necessitating adjuvant chemoradiotherapy. The blood-brain barrier hinders many chemotherapeutic agents, resulting in modest treatment efficacy. We previously demonstrated that targeted natural killer (NK)-92 cells could be delivered to desired regions of the brain using MRI-guided focused ultrasound and Definity microbubbles. Targeted NK-92 cells have advantages over many systemic therapies including their specific cytotoxicity to malignant cells (particularly those expressing the target antigen), ability to spare healthy cells, and being unaffected by efflux channels.

METHODS

We investigated whether longitudinal treatments with targeted NK-92 cells, focused ultrasound, and microbubbles could slow tumor growth and improve survival in an orthotopic HER2-amplified rodent brain tumor model using a human breast cancer line as a prototype. The HER2 receptor, involved in cell growth and differentiation, is expressed by both primary and metastatic brain tumors. Breast cancers with HER2 amplification have a higher risk of CNS metastasis and poorer prognosis.

RESULTS

Early intensive treatment with targeted NK-92 cells and ultrasound improved survival compared with biweekly treatments or either treatment alone. The intensive treatment paradigm resulted in long-term survival in 50% of subjects.

CONCLUSIONS

Many tumor proteins could be exploited for targeted therapy with the NK-92 cell line; combined with the mounting safety evidence for transcranial ultrasound, these results may soon be translatable to a highly targeted treatment option for patients with brain tumors.

A Phase 2 Study of Concurrent Radiation Therapy, Temozolomide, and the Histone Deacetylase Inhibitor Valproic Acid for Patients With Glioblastoma

PURPOSE

Valproic acid (VPA) is an antiepileptic agent with histone deacetylase inhibitor (HDACi) activity shown to sensitize glioblastoma (GBM) cells to radiation in preclinical models. We evaluated the addition of VPA to standard radiation therapy (RT) plus temozolomide (TMZ) in patients with newly diagnosed GBM.

METHODS AND MATERIALS

Thirty-seven patients with newly diagnosed GBM were enrolled between July 2006 and April 2013. Patients received VPA, 25 mg/kg orally, divided into 2 daily doses concurrent with RT and TMZ. The first dose of VPA was given 1 week before the first day of RT at 10 to 15 mg/kg/day and subsequently increased up to 25 mg/kg/day over the week prior to radiation. VPA- and TMZ-related acute toxicities were evaluated using Common Toxicity Criteria version 3.0 (National Cancer Institute Cancer Therapy Evaluation Program) and Cancer Radiation Morbidity Scoring Scheme for toxicity and adverse event reporting (Radiation Therapy Oncology Group/European Organization for Research and Treatment).

RESULTS

A total of 81% of patients took VPA according to protocol. Median overall survival (OS) was 29.6 months (range: 21-63.8 months), and median progression-free survival (PFS) was 10.5 months (range: 6.8-51.2 months). OS at 6, 12, and 24 months was 97%, 86%, and 56%, respectively. PFS at 6, 12, and 24 months was 70%, 43%, and 38% respectively. The most common grade 3/4 toxicities of VPA in conjunction with RT/TMZ therapy were blood and bone marrow toxicity (32%), neurological toxicity (11%), and metabolic and laboratory toxicity (8%). Younger age and class V recursive partitioning analysis (RPA) results were significant for both OS and PFS. VPA levels were not correlated with grade 3 or 4 toxicity levels.

CONCLUSIONS

Addition of VPA to concurrent RT/TMZ in patients with newly diagnosed GBM was well tolerated. Additionally, VPA may result in improved outcomes compared to historical data and merits further study.

KML001, a telomere-targeting drug, sensitizes glioblastoma cells to temozolomide chemotherapy and radiotherapy through DNA damage and apoptosis

Standard treatment for glioblastoma comprises surgical resection, chemotherapy with temozolomide, and radiotherapy. Nevertheless, majority of glioblastoma patients have recurrence from resistance to the cytotoxic conventional therapies. We examined combinational effects of KML001, an arsenic compound targeting telomeres of chromosomes with temozolomide or irradiation, in glioblastoma cell lines and xenograft models, to overcome the therapeutic limitation of chemoradiation therapy for glioblastoma. Although KML001 alone showed little effects on in vitro survival of glioblastoma cells, cell death by in vitro temozolomide treatment or irradiation was synergistically potentiated by combination with KML001. Since phosphorylated γ-H2AX, cleaved casepase-3, and cleaved PARP were dramatically increased by KML001, the synergistic effects would be mediated by increased DNA damage and subsequent tumor cell apoptosis. Combinatorial effects of KML001 were observed not only in chemo- and radiosensitive glioblastoma cell line, U87MG, but also in the resistant cell line, U251MG. In the U87MG glioblastoma xenograft models, KML001 did not have systemic toxicity but showed synergistic therapeutic effects in combination with temozolomide or irradiation to reduce tumor volumes significantly. These data indicated that KML001 could be a candidate sensitizer to potentiate therapeutic effects of conventional cytotoxic treatment for glioblastoma.

Survival in Patients with Newly Diagnosed Conventional Glioblastoma: A Modified Prognostic Score Based on a Single-Institution Series

Aims and background

Recursive partioning analysis (RPA) is commonly used to define the stratification of patients with glioblastoma. Epigenetic silencing of the O6-methylguanine methyltransferase (MGMT) gene by promoter methylation plays an important role in regulating MGMT expression in gliomas and this is an established independent prognostic factor. We tested a prognostic scoring system including all clinical variables used by RPA classification (age, ECOG performance status and type of surgery) and MGMT gene promoter methylation status.

Methods

Seventy-eight consecutive patients with newly diagnosed, histopathologically confirmed conventional glioblastoma were included. Information about MGMT promoter methylation status was available for all of them. Based on the patients' age (<50 vs ≥50 years), ECOG performance status (0 vs ≥1), type of surgery (gross tumor resection versus partial resection/biopsy) and MGMT promoter methylation status (methylated versus unmethylated), three classes of risk were generated where the prognostic score was defined assigning 1 point to every favorable parameter (Class I: ≥3; Class II: 2; Class III: 0–1). All classes were correlated with overall survival.

Results

The median survival times were 32.4, 8.6 and 8.8 months for Class I, II and III, respectively, corresponding to 2-year survival rates of 69%, 13.5% and <1%. The same analysis was performed on 54 patients treated with postoperative concomitant chemoradiotherapy. The median survival times were 32.5, 13.4 and 8.9 months for Class I, II and III, respectively, corresponding to 2-year survival rates of 68.6%, 26.9% and <1%. In both groups of 78 and 54 patients the differences in survival between Class I and III were statistically significant (P <0.0001).

Conclusions

The proposed prognostic scoring system including clinical variables and MGMT promoter methylation status proved valuable in patients with primary conventional glioblastoma, especially those treated with postoperative chemoradiotherapy.

Modification of loco-regional microenvironment in brain tumors by spinal cord stimulation. Implications for radio-chemotherapy

The effectiveness of radiotherapy and chemotherapy in high grade gliomas (HGG) depends on tumor micro-environment. We summarize our experience of the influence of spinal cord stimulation (SCS) on this micro-environment. Patients with HGG (n = 26) were assessed pre- and post-SCS, using: (1) Doppler in middle cerebral arteries (MCA) and (2) in common carotid arteries (CCA); (3) tumor blood-flow using single photon emission computed tomography (SPECT); (4) tumor-pO(2) (mmHg) using polarographic probes (eight tumor areas from five patients); and (5) tumor glucose metabolism using (18)F-fluoro-2-deoxyglucose ((18)FDG) positron emission tomography ((18)FDG-PET). Pre-SCS: tumor blood-flow was lower (P < 0.001) than peri-tumor areas and healthy contra-lateral areas. Tumor-pO(2) was lower (P < 0.042) than healthy tissue. Tumor glucose metabolism was higher than peri-tumor areas (P = 0.017) and healthy contra-lateral areas (P = 0.048). Post-SCS: there were increases in: MCA blood-flow (P ≤ 0.002), CCA blood-flow (P ≤ 0.013), tumor blood-flow (P = 0.033), tumor glucose metabolism (P = 0.027) and tumor-pO(2) (P = 0.022). The percentage of hypoxic values decreased (P = 0.007). SCS can modify tumor micro-environment. The potential usefulness of SCS in improving the effectiveness of radio-chemotherapy in HGG needs to be evaluated.

Quantitative MRI assessment of VX2 tumour oxygenation changes in response to hyperoxia and hypercapnia

Magnetic resonance imaging (MRI) relaxation times provide indirect estimates of tissue O(2) for monitoring tumour oxygenation. This study provides insight into mechanisms underlying longitudinal (R(1) = 1/T(1)) and transverse effective (R(2)* = 1/T(2)*) relaxation rate changes during inhalation of 100% O(2) and 3%, 6% and 9% CO(2) (balanced O(2)) in a rabbit tumour model. Quantitative R(1), R(2)*, and dynamic contrast-enhanced (DCE) imaging was performed in six rabbits 12-23 days following implantation of VX2 carcinoma cells in the quadricep muscle. Invasive measurements of tissue partial pressure of O(2) (pO(2)) and perfusion were also performed, which revealed elevated pO(2) levels in all tumour regions for all hyperoxic gases compared to baseline (air) and reduced perfusion for carbogen. During 100% O(2) breathing, an R(1) increase and R(2)* decrease consistent with elevated pO(2) were observed within tumours. DCE-derived blood flow was weakly correlated with R(1) changes from air to 100% O(2). Further addition of CO(2) (carbogen) did not introduce considerable changes in MR relaxation rates, but a trend towards higher R(1) relative to breathing 100% O(2) was observed, while R(2)* changes were inconsistent. This observation supports the predominance of dissolved O(2) on R(1) sensitivity and demonstrates the value of R(1) over R(2)* for tissue oxygenation measures.

Radiotherapy and temozolomide for newly diagnosed glioblastoma and anaplastic astrocytoma: validation of Radiation Therapy Oncology Group-Recursive Partitioning Analysis in the IMRT and temozolomide era

Since the development of the Radiation Therapy Oncology Group-Recursive Partitioning Analysis (RTOG-RPA) risk classes for high-grade glioma, radiation therapy in combination with temozolomide (TMZ) has become standard care. While this combination has improved survival, the prognosis remains poor in the majority of patients. Therefore, strong interest in high-grade gliomas from basic research to clinical trials persists. We sought to evaluate whether the current RTOG-RPA retains prognostic significance in the TMZ era or alternatively, if modifications better prognosticate the optimal selection of patients with similar baseline prognosis for future clinical protocols. The records of 159 patients with newly-diagnosed glioblastoma (GBM, WHO grade IV) or anaplastic astrocytoma (AA, WHO grade III) were reviewed. Patients were treated with intensity-modulated radiation therapy (IMRT) and concurrent followed by adjuvant TMZ (n = 154) or adjuvant TMZ only (n = 5). The primary endpoint was overall survival. Three separate analyses were performed: (1) application of RTOG-RPA to the study cohort and calculation of subsequent survival curves, (2) fit a new tree model with the same predictors in RTOG-RPA, and (3) fit a new tree model with an expanded predictor set. All analyses used a regression tree analysis with a survival outcome fit to formulate new risk classes. Overall median survival was 14.9 months. Using the RTOG-RPA, the six classes retained their relative prognostic significance and overall ordering, with the corresponding survival distributions significantly different from each other (P < 0.01, χ² statistic = 70). New recursive partitioning limited to the predictors in RTOG-RPA defined four risk groups based on Karnofsky Performance Status (KPS), histology, age, length of neurologic symptoms, and mental status. Analysis across the expanded predictors defined six risk classes, including the same five variables plus tumor location, tobacco use, and hospitalization during radiation therapy. Patients with excellent functional status, AA, and frontal lobe tumors had the best prognosis. For patients with newly-diagnosed high-grade gliomas, RTOG-RPA classes retained prognostic significance in patients treated with TMZ and IMRT. In contrast to RTOG-RPA, in our modified RPA model, KPS rather than age represented the initial split. New recursive partitioning identified potential modifications to RTOG-RPA that should be further explored with a larger data set.

Improving the radiosensitivity of radioresistant and hypoxic glioblastoma

In spite of increasing attention on targeted therapeutics in the treatment of glioblastoma multiforme, radiation therapy remains the most clinically effective treatment modality. However, radiotherapy only offers palliation, with hypoxia representing a major mechanism of tumor resistance. Traditional strategies to overcome the therapeutic barrier to irradiation imposed by tumor tissue hypoxia consist of improving tumor oxygenation and administering agents that increase the tumor cell sensitivity to irradiation (radiosensitizers). There is also increasing evidence that tumor tissue is composed of diverse populations of cells with heterogeneous sensitivities to irradiation. The radioresistant tumor-initiating CD133-positive glioblastoma cancer stem cells are preferentially expanded in hypoxic conditions. Therefore, identifying therapies that can specifically target the glioblastoma cancer stem cells will lead to more durable responses to radiation therapy.

Validation and simplification of the Radiation Therapy Oncology Group recursive partitioning analysis classification for glioblastoma

PURPOSE

Previous recursive partitioning analysis (RPA) of patients with malignant glioma (glioblastoma multiforme [GBM] and anaplastic astrocytoma [AA]) produced six prognostic groups (I-VI) classified by six factors. We sought here to determine whether the classification for GBM could be improved by using an updated Radiation Therapy Oncology Group (RTOG) GBM database excluding AA and by considering additional baseline variables.

METHODS AND MATERIALS

The new analysis considered 42 baseline variables and 1,672 GBM patients from the expanded RTOG glioma database. Patients receiving radiation only were excluded such that all patients received radiation+carmustine. "Radiation dose received" was replaced with "radiation dose assigned." The new RPA models were compared with the original model by applying them to a test dataset comprising 488 patients from six other RTOG trials. Fitness of the original and new models was evaluated using explained variation.

RESULTS

The original RPA model explained more variations in survival in the test dataset than did the new models (20% vs. 15%) and was therefore chosen for further analysis. It was reduced by combining Classes V and VI to produce three prognostic classes (Classes III, IV, and V+VI), as Classes V and VI had indistinguishable survival in the test dataset. The simplified model did not further improve performance (explained variation 18% vs. 20%) but is easier to apply because it involves only four variables: age, performance status, extent of resection, and neurologic function. Applying this simplified model to the updated GBM database resulted in three distinct classes with median survival times of 17.1, 11.2, and 7.5 months for Classes III, IV, and V+VI, respectively.

CONCLUSIONS

The final model, the simplified original RPA model combining Classes V and VI, resulted in three distinct prognostic groups defined by age, performance status, extent of resection, and neurologic function. This classification will be used in future RTOG GBM trials.

Effect of a topical vasodilator on tumor hypoxia and tumor oxygen guided radiotherapy using EPR oximetry

We sought to reduce tumor hypoxia by topical application of a vasodilator, benzyl nicotinate (BN), and investigated its effect on the growth of tumors irradiated at times when tumor pO(2) increased. EPR oximetry was used to follow the changes in the tissue pO(2) of subcutaneous radiation-induced fibrosarcoma (RIF-1) tumors during topical applications of 1.25-8% BN formulations for 5 consecutive days. The RIF-1 tumors were hypoxic with a tissue pO(2) of 4.6-7.0 mmHg. A significant increase in tumor pO(2) occurred 10-30 min after BN application. The formulation with the minimal BN concentration that produced a significant increase in tumor pO(2) was used for the radiation study. The tumors were irradiated (4 Gy x 5) at the time of the maximum increase in pO(2) observed with the 2.5% BN formulation. The tumors with an increase in pO(2) of greater than 2 mmHg from the baseline after application of BN on day 1 had a significant growth inhibition compared to the tumors with an increase in pO(2) of less than 2 mmHg. The results indicate that the irradiation of tumors at the time of an increase in pO(2) after the topical application of the 2.5% BN formulation led to a significant growth inhibition. EPR oximetry provided dynamic information on the changes in tumor pO(2), which could be used to identify responders and non-responders and schedule therapy during the experiments.

Safety considerations and potential interactions of vitamins: should vitamins be considered drugs?

OBJECTIVE

To examine adverse effects, adverse events, and potential interactions of vitamins in light of their current prevalence of use, and to discuss whether vitamins should be considered over-the-counter drugs or natural health products/dietary supplements.

DATA SOURCES

We performed a MEDLINE/PubMed search, explored 4 online databases (Medline Plus, Drug Digest, Natural Medicine Comprehensive Database, and the database of the University of Maryland), and examined reference lists of included studies published from 1966 through October 2009.

STUDY SELECTION AND DATA EXTRACTION

The studies were reviewed, with an emphasis on randomized controlled clinical trials. We included articles with the most clinically important information with regard to adverse events and interactions.

DATA SYNTHESIS

Vitamins are used by over one third of the North American population. Vitamins have documented adverse effects and toxicities, and most have documented interactions with drugs. While some vitamins (biotin, pantothenic acid, riboflavin, thiamine, vitamin B(12), vitamin K) have minor and reversible adverse effects, others, such as fat-soluble vitamins (A, E, D), can cause serious adverse events. Two water-soluble vitamins, folic acid and niacin, can also have significant toxicities and adverse events.

CONCLUSIONS

Our recommendation is that vitamins A, E, D, folic acid, and niacin should be categorized as over-the-counter medications. Labeling of vitamins, especially those intended for children and other vulnerable groups, should include information on possible toxicities, dosing, recommended upper intake limits, and concurrent use with other products. Vitamin A should be excluded from multivitamin supplements and food fortificants.

Effects of radiotherapy with concomitant and adjuvant temozolomide versus radiotherapy alone on survival in glioblastoma in a randomised phase III study: 5-year analysis of the EORTC-NCIC trial

BACKGROUND

In 2004, a randomised phase III trial by the European Organisation for Research and Treatment of Cancer (EORTC) and National Cancer Institute of Canada Clinical Trials Group (NCIC) reported improved median and 2-year survival for patients with glioblastoma treated with concomitant and adjuvant temozolomide and radiotherapy. We report the final results with a median follow-up of more than 5 years.

METHODS

Adult patients with newly diagnosed glioblastoma were randomly assigned to receive either standard radiotherapy or identical radiotherapy with concomitant temozolomide followed by up to six cycles of adjuvant temozolomide. The methylation status of the methyl-guanine methyl transferase gene, MGMT, was determined retrospectively from the tumour tissue of 206 patients. The primary endpoint was overall survival. Analyses were by intention to treat. This trial is registered with Clinicaltrials.gov, number NCT00006353.

FINDINGS

Between Aug 17, 2000, and March 22, 2002, 573 patients were assigned to treatment. 278 (97%) of 286 patients in the radiotherapy alone group and 254 (89%) of 287 in the combined-treatment group died during 5 years of follow-up. Overall survival was 27.2% (95% CI 22.2-32.5) at 2 years, 16.0% (12.0-20.6) at 3 years, 12.1% (8.5-16.4) at 4 years, and 9.8% (6.4-14.0) at 5 years with temozolomide, versus 10.9% (7.6-14.8), 4.4% (2.4-7.2), 3.0% (1.4-5.7), and 1.9% (0.6-4.4) with radiotherapy alone (hazard ratio 0.6, 95% CI 0.5-0.7; p<0.0001). A benefit of combined therapy was recorded in all clinical prognostic subgroups, including patients aged 60-70 years. Methylation of the MGMT promoter was the strongest predictor for outcome and benefit from temozolomide chemotherapy.

INTERPRETATION

Benefits of adjuvant temozolomide with radiotherapy lasted throughout 5 years of follow-up. A few patients in favourable prognostic categories survive longer than 5 years. MGMT methylation status identifies patients most likely to benefit from the addition of temozolomide.

FUNDING

EORTC, NCIC, Nélia and Amadeo Barletta Foundation, Schering-Plough.

Resection and survival in glioblastoma multiforme: an RTOG recursive partitioning analysis of ALA study patients

The benefit of cytoreductive surgery for glioblastoma multiforme (GBM) is unclear, and selection bias in past series has been observed. The 5-aminolevulinic acid (ALA) study investigated the influence of fluorescence-guided resections on outcome and generated an extensive database of GBM patients with optimized resections. We evaluated whether the Radiation Therapy Oncology Group recursive partitioning analysis (RTOG-RPA) would predict survival of these patients and whether there was any benefit from extensive resections depending on RPA class. A total of 243 per-protocol patients with newly diagnosed GBM were operated on with or without ALA and treated by radiotherapy. Postoperative MRI was obtained in all patients. Patients were allocated into RTOG-RPA classes III-V based on age, KPS, neurological condition, and mental status (as derived from the NIH Stroke Scale). Median overall survival among RPA classes III, IV, and V was 17.8, 14.7, and 10.7 months, respectively, with 2-year survival rates of 26%, 12%, and 7% (p = 0.0007). Stratified for degree of resection, survival of patients with complete resections was clearly longer in RPA classes IV and V (17.7 months vs. 12.9 months, p = 0.0015, and 13.7 months vs. 10.4 months, p = 0.0398; 2-year rates: 21.0% vs. 4.4% and 11.1% vs. 2.6%, respectively), but was not in the small subgroup of RPA class III patients (19.3 vs. 16.3 months, p = 0.14). Survival of patients from the ALA study is correctly predicted by the RTOG-RPA classes. Differences in survival depending on resection status, especially in RPA classes IV and V, support a causal influence of resection on survival.

Use of trans sodium crocetinate for sensitizing glioblastoma multiforme to radiation

Object

Adjuvant treatment with radiation (radiation therapy or radiosurgery) is a mainstay of treatment for patients harboring glioblastomas multiforme (GBM). Hypoxic regions within the tumor make cells less sensitive to radiation therapy. Trans sodium crocetinate (TSC) has been shown to increase oxygen diffusion in the brain and elevate the partial brain oxygen level. The goal of this study was to evaluate the radiosensitizing effects of TSC on GBM tumors.

Methods

A rat C6 glioma model was used, in which C6 glioma cells were stereotactically injected into the rat brain to create a tumor. Following creation of a right frontal tumor, animals were randomized into 1 of 4 groups: 1) TSC alone (animal treated with moderate-dose TSC only); 2) radiation (animals receiving 8 Gy of cranial radiation); 3) radiation and low-dose TSC (animals receiving 8 Gy of radiation and 50 μg/kg of TSC); or 4) radiation and moderate-dose TSC (animals receiving 8 Gy of radiation and 100 μg/kg of TSC). Animals were observed clinically for 60 days or until death. Magnetic resonance (MR) imaging was performed at 2-week intervals on each animal and quantitatively evaluated for tumor response. Immunohistochemical analysis was performed on all brain tumors. Survival differences were also evaluated using the Kaplan–Meier method.

Results

On MR imaging, a statistically significant reduction in tumor size was seen in the group receiving moderate-dose TSC and radiation treatment compared with the group receiving radiation treatment alone. The rate of tumor growth was significantly less for the combination of TSC and radiation treatment compared with either modality alone. Median survival times for the TSC-only and the radiation therapy–only groups were 15 and 30 days, respectively. The 60-day median survival times for the groups receiving a combination of either low- or moderate-dose TSC with radiation therapy were statistically improved compared with those for the other treatment groups.

Conclusions

Use of TSC improves the extent of GBM tumor regression following radiation therapy and enhances survival. Radiosensitization of hypoxic tumors through increased oxygen diffusion may have clinical utility in patients with GBM tumors but must be explored in a clinical trial.

Biocomputing: numerical simulation of glioblastoma growth using diffusion tensor imaging

Glioblastoma multiforma (GBM) is one of the most aggressive tumors of the central nervous system. It can be represented by two components: a proliferative component with a mass effect on brain structures and an invasive component. GBM has a distinct pattern of spread showing a preferential growth in the white fiber direction for the invasive component. By using the architecture of white matter fibers, we propose a new model to simulate the growth of GBM. This architecture is estimated by diffusion tensor imaging in order to determine the preferred direction for the diffusion component. It is then coupled with a mechanical component. To set up our growth model, we make a brain atlas including brain structures with a distinct response to tumor aggressiveness, white fiber diffusion tensor information and elasticity. In this atlas, we introduce a virtual GBM with a mechanical component coupled with a diffusion component. These two components are complementary, and can be tuned independently. Then, we tune the parameter set of our model with an MRI patient. We have compared simulated growth (initialized with the MRI patient) with observed growth six months later. The average and the odd ratio of image difference between observed and simulated images are computed. Displacements of reference points are compared to those simulated by the model. The results of our simulation have shown a good correlation with tumor growth, as observed on an MRI patient. Different tumor aggressiveness can also be simulated by tuning additional parameters. This work has demonstrated that modeling the complex behavior of brain tumors is feasible and will account for further validation of this new conceptual approach.

Modified oxygen mask to induce target levels of hyperoxia and hypercarbia during radiotherapy: a more effective alternative to carbogen

PURPOSE

Carbogen has long been under investigation as an adjuvant to radiotherapy of tumors. A major factor confounding its evaluation is its inconsistency in raising blood partial pressure of CO(2) (pCO(2)). We investigated whether a new partial rebreathing method would provide better control of pCO(2) than carbogen.

METHODS AND MATERIALS

We compared the efficacy of each method in 10 healthy volunteers. Volunteers breathed 1.5, 3 and 5% carbogen in 5-min stages via the usual non-rebreathing circuit. All the volunteers then breathed 100% O(2) through a commercial sequential gas delivery (SGD) circuit modified by attaching a reservoir to its exhalation port. Hypercarbia was induced by step reductions in oxygen flow to the SGD circuit. We monitored minute ventilation and end-tidal pCO(2) (ETpCO(2)) as a surrogate for its arterial value.

RESULTS

Inhalation of 1.5 and 3% carbogen did not increase ETpCO(2) from baseline (40 +/- 1.5 mmHg); 5% carbogen increased ETpCO(2) to 45 +/- 1.6 mmHg (p < 0.001). With the SGD circuit, reducing O(2) flow to 4.3 +/- 0.7 l/min increased ETpCO(2) in all subjects from 41 +/- 2.0 mmHg (baseline) to 46 +/- 2.1 mmHg (p < 0.001). Voluntary hyperventilation reduced ETpCO(2) with 5% carbogen but not with SGD (p = 0.379).

CONCLUSIONS

We confirm previous observations that carbogen inhalation does not result in a predictable rise in ETpCO(2) and suggest that a precise and stable target ETpCO(2) can instead be induced by simply controlling O(2) flow into a modified SGD circuit. We hoped that the reliable control of pCO(2) will enable studies that address first, the efficacy of raising ETpCO(2) on specific tumor blood flow, and eventually, its benefit as an adjuvant to radiotherapy.

Expression patterns of the hypoxia-related genes osteopontin, CA9, erythropoietin, VEGF and HIF-1alpha in human glioma in vitro and in vivo

BACKGROUND AND PURPOSE

To identify molecular markers of tumor hypoxia and potential therapeutic targets in glioblastoma (GBM), we investigated the hypoxia-related expression of osteopontin (OPN), carbonic anhydrase 9 (CA9), erythropoietin (EPO), vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1alpha (HIF-1alpha) in vitro in human GBM cell lines and in vivo in human tumor samples of GBM, compared to low-grade astrocytoma (LGA).

MATERIALS AND METHODS

Expression of the hypoxia-induced genes OPN, CA9, EPO, VEGF and HIF-1alpha was analyzed in three GBM cell lines, GaMG, U373 and U251, under in vitro hypoxia (1, 6 or 24h at 5%, 1% or 0.1% O(2)) and in tumor samples from two patient groups with LGA and GBM (n=15 each), at the mRNA level (semiquantitative RT-PCR). Selected conditions and representative tumor samples were also evaluated at the protein level by Western blot.

RESULTS

OPN and CA9 mRNA was most consistently upregulated in relation to severity and duration of in vitro hypoxia. In tumor samples, mean expression levels (LGA vs. GBM, normalized to mean expression in normal brain) were 1.71 vs. 4.57 (p<0.001) for OPN, 1.11 vs. 3.35 (p<0.001) for CA9, 2.79 vs. 5.28 (not significant, n.s.) for Epo, 1.13 vs. 2.0 (p=0.007) for VEGF and 0.97 vs. 0.97 (n.s.) for HIF-1alpha. In tumor samples, GBM showed a particularly strong protein expression of OPN.

CONCLUSIONS

Among a panel of known hypoxia-inducible genes, OPN and CA9 emerge as most consistently induced by in vitro hypoxia in human GBM cell lines and most specifically expressed in patient GBM tumor tissue, rendering these two genes attractive targets for hypoxia-directed treatment approaches.

The hypoxic tumour microenvironment, patient selection and hypoxia-modifying treatments

Tumour hypoxia has been found to be a characteristic feature in many solid tumours. It has been shown to decrease the therapeutic efficacy of radiation treatment, surgery and some forms of chemotherapy. Successful approaches have been developed to counteract this resistance mechanism, although usually at the cost of increased short- and long-term side-effects. New methods for qualitative and quantitative assessment of tumour oxygenation have made it possible to establish the prognostic significance of tumour hypoxia. The ability to determine the degree and extent of hypoxia in solid tumours is not only important prognostically, but also in the selection of patients for hypoxia-modifying treatments. To provide the best attainable quality of life for individual patients it is of increasing importance that tools be developed that allow a better selection of patients for these intensified treatment strategies. Several genes and proteins involved in the response to hypoxia have been identified as potential candidates for future use in predictive assays. Although some markers and combinations have shown potential benefit and are associated with treatment outcome, their clinical usefulness needs to be validated in prospective trials. A review of published studies was carried out, focusing on the assessment of tumour hypoxia, patient selection and the possibilities to overcome hypoxia during treatment.

Cerebral blood flow increase in cancer patients by applying cervical spinal cord stimulation

INTRODUCTION

Generally, high-grade gliomas and head and neck tumors have decreased loco-regional blood flow resulting in reduced delivery of chemotherapy and oxygen, as well as an increases in radiation resistance to radiotherapy. The aim of this study was to analyze the effect of cervical spinal cord electrical stimulation (cSCS) on cerebral blood flow in patients with those tumors.

PATIENTS AND METHODS

We have evaluated 27 cancer patients with 12 with high grade gliomas and 15 with advanced head and neck tumors, who had cSCS devices placed after tumor diagnoses and before the commencement initiating of radio-chemotherapy. They were 12 high grade gliomas and 15 advanced head and neck tumors. Before and after cSCS, cerebral blood flow was assessed bilaterally by transcranial Doppler.

RESULTS

During cSCS there was a significant (p<0.001) increase in systolic (mean > 22%) and diastolic (> 29%) blood-flow velocities in both, healthy and tumor middle cerebral arteries. The analyses by subgroup of tumors showed similarly significant outcomes findings.

CONCLUSIONS

The results suggest that neuro-stimulation spinal cord electrical stimulation can increase cerebral blood flow in cancer patients. The implication is that this technique could be useful in modifying locoregional ischemia in brain tumors thus improving the outcomes of after radio-chemotherapy. Further research is in progress to confirm the advantages of the technique.

The role of spinal cord stimulation in the management of patients with brain tumors

High grade gliomas (HGG) have decreased blood flow resulting in hypoxia, limited access by chemotherapeutic agents, and reduced radiation-sensitivity. Spinal cord stimulation (SCS) has been used successfully in the treatment of pain and ischemic syndromes. The present article summarizes our investigations into the effects of SCS in patients with HGG. Before their scheduled radio-chemotherapy, 23 patients with HGG were assessed pre- and post-SCS using several evaluation techniques: (1) transcranial Doppler (TCD) for middle cerebral artery blood flow; (2) color Doppler for common carotid artery blood flow; (3) single photon emission computed tomography (SPECT) for tumor blood flow; (4) polarographic probe technique for tumor pO2 measurement; (5) positron emission tomography (PET) for tumor glucose metabolism. Pre-SCS, the tumors were more ischemic and more hypoxic than healthy tissues. Post-SCS, there was significant: (1) increase in blood flow measured by TCD (> or =18%), color Doppler (> or =61%) and SPECT (15%), (2) increase in oxygenation and decrease (> or =45%) in percentage of hypoxic values <10 mmHg and <5 mmHg, and (3) increase (43%) in glucose metabolism. Our studies show that SCS can modify loco-regional blood flow and oxygen supply, as well as glucose-metabolism in HGG. This suggests that SCS could prove useful as an adjuvant treatment to radio-chemotherapy. These data merit further confirmatory studies.

The evolution of chemoradiation for glioblastoma: a modern success story

The dismal prognosis of glioblastoma had remained unchanged for the past 30 years until the association of temozolomide and radiotherapy in the breakthrough European Organization for Cancer/National Cancer Institute of Canada (EORTC/NCIC) trial brought new hope for patients. This trial will serve as a platform for new and exciting clinical and translational research areas. We review here the role of standard radiotherapy and chemotherapy in glioblastoma and the potential causes of their failure, and we focus on some of the aspects that led to the successful EORTC/NCIC trial and some of the related studies.

Radiotherapy and Temozolomide for Newly Diagnosed Glioblastoma: Recursive Partitioning Analysis of the EORTC 26981/22981-NCIC CE3 Phase III Randomized Trial

Purpose

The European Organisation for Research and Treatment of Cancer and National Cancer Institute of Canada trial on temozolomide (TMZ) and radiotherapy (RT) in glioblastoma (GBM) has demonstrated that the combination of TMZ and RT conferred a significant and meaningful survival advantage compared with RT alone. We evaluated in this trial whether the recursive partitioning analysis (RPA) retains its overall prognostic value and what the benefit of the combined modality is in each RPA class.

Patients and Methods

Five hundred seventy-three patients with newly diagnosed GBM were randomly assigned to standard postoperative RT or to the same RT with concomitant TMZ followed by adjuvant TMZ. The primary end point was overall survival. The European Organisation for Research and Treatment of Cancer RPA used accounts for age, WHO performance status, extent of surgery, and the Mini-Mental Status Examination.

Results

Overall survival was statistically different among RPA classes III, IV, and V, with median survival times of 17, 15, and 10 months, respectively, and 2-year survival rates of 32%, 19%, and 11%, respectively (P < .0001). Survival with combined TMZ/RT was higher in RPA class III, with 21 months median survival time and a 43% 2-year survival rate, versus 15 months and 20% for RT alone (P = .006). In RPA class IV, the survival advantage remained significant, with median survival times of 16 v 13 months, respectively, and 2-year survival rates of 28% v 11%, respectively (P = .0001). In RPA class V, however, the survival advantage of RT/TMZ was of borderline significance (P = .054).

Conclusion

RPA retains its prognostic significance overall as well as in patients receiving RT with or without TMZ for newly diagnosed GBM, particularly in classes III and IV.

High-dose conformal radiotherapy for supratentorial malignant glioma: a historical comparison

BACKGROUND

Although radiotherapy remains the main postoperative treatment for patients with malignant glioma, modifications to regimens have not improved the poor outlook of patients with this disease. We aimed to investigate whether high-dose conformal radiotherapy improves the survival of patients with supratentorial malignant glioma compared with conventional radiotherapy.

METHODS

29 patients with anaplastic astrocytoma and 61 patients with glioblastoma who received high-dose conformal radiotherapy during 1990-2002 were compared with 34 patients with anaplastic astrocytoma and 60 patients with glioblastoma who received conventional 60 Gy radiotherapy during 1979-89. 77 of the 90 patients receiving high-dose radiotherapy were given 80 Gy; the remaining 13 patients, all with glioblastoma, received 90 Gy. Radiotherapy was planned on the basis of images taken before surgery, and doses were delivered in 2 Gy per fraction per day for 5 days a week. Hazard ratios for death were calculated with a Cox model, and were adjusted for age, Karnofsky performance scale, tumour size, and extent of resection.

FINDINGS

Patients who received high-dose radiotherapy had significantly longer overall survival compared with those who received conventional radiotherapy (adjusted hazard ratio 0.30 [95% CI 0.12-0.76], p=0.011 for anaplastic astrocytoma and 0.49 [0.28-0.87], p=0.014 for glioblastoma). Patients with anaplastic astrocytoma in the high-dose group have not yet reached median survival; median survival in the conventional radiotherapy group was 22.3 months (95% CI 20.6-24.0). 5-year survival was 51.3% (29.2-73.4) for the high-dose group and 14.7% (0.0-30.0) for the conventional group. Median survival in patients with glioblastoma was 16.2 months (12.8-19.6) for the high-dose group and 12.4 months (10.0-14.8) for the conventional group. 2-year survival was 38.4% (23.5-53.3) for the high-dose group and 11.4% (0.0-25.3) for the conventional group. Survival did not differ between those that received 80 Gy radiotherapy and those that received 90 Gy (hazard ratio 0.94 [95% CI 0.42-2.12]). The higher frequency of radiation-induced white matter abnormality in the high-dose group compared with the conventional radiotherapy group did not lead to increased disability.

INTERPRETATION

High-dose, standard-fractionated radiotherapy shows potential as the main postoperative treatment for patients with supratentorial malignant glioma.

Radiothérapie des glioblastomes : de la radiobiologie à la chimiothérapie concomitante

The prognosis of glioblastoma remains extremely poor. Clinical research has been very active for thirty years, and has explored all the concepts developed in the laboratories of radiobiology. Radiosensitisation of hypoxic tumours, hyperfractioned radiotherapy, external beam radiotherapy plus stereotactic radiosurgery or brachytherapy boost, and intensity modulated radiation therapy failed to improve the results of the treatment of these patients. Concomitant chemoradiotherapy has just obtained a new success in the treatment of glioblastoma. The addition of temozolomide to radiotherapy resulted in a statistically significant survival benefit with minimal acute additional toxicity. The challenge remains to improve clinical outcomes further, and some new research pathways are open.

Hypoxia inducible factor pathways as targets for functional foods

The etiology of most chronic angiogenic diseases such as rheumatoid arthritis, atherosclerosis, diabetes complications, and cancer includes the presence of pockets of hypoxic cells growing behind aerobic cells and away from blood vessels. Hypoxic cells are the result of uncontrolled growth and insufficient vascularization and have undergone a shift from aerobic to anaerobic metabolism. Cells respond to hypoxia by stimulating the expression of hypoxia inducible factor (HIF), which is critical for survival under hypoxic conditions and in embryogenesis. HIF is a heterodimer consisting of the O2-regulated subunit, HIF-1alpha, and the constitutively expressed aryl hydrocarbon receptor nuclear translocator, HIF-1beta. Under hypoxic conditions, HIF-1alpha is stable, accumulates, and migrates to the nucleus where it binds to HIF-1beta to form the complex (HIF-1alpha + HIF-1beta). Transcription is initiated by the binding of the complex (HIF-1alpha + HIF-1beta) to hypoxia responsive elements (HREs). The complex [(HIF-1alpha + HIF-1beta) + HREs] stimulates the expression of genes involved in angiogenesis, anaerobic metabolism, vascular permeability, and inflammation. Experimental and clinical evidence show that these hypoxic cells are the most aggressive and difficult angiogenic disease cells to treat and are a major reason for antiangiogenic and conventional treatment failure. Hypoxia occurs in early stages of disease development (before metastasis), activates angiogenesis, and stimulates vascular remodeling. HIF-1alpha has also been identified under aerobic conditions in certain types of cancer. This review summarizes the role of hypoxia in some chronic degenerative angiogenic diseases and discusses potential functional foods to target the HIF-1alpha pathways under hypoxic and normoxic conditions. It is reported that dietary quinones, semiquinones, phenolics, vitamins, amino acids, isoprenoids, and vasoactive compounds can down-regulate the HIF-1 pathways and therefore the expression of several proangiogenic factors. Considering the lack of efficiency or the side effects of synthetic antiangiogenic drugs at clinical trials, down-regulation of hypoxia-induced angiogenesis by use of naturally occurring functional foods may provide an effective means of prevention.

Hypoxia augments gelatinase activity in a variety of adenocarcinomas in vitro

BACKGROUND

Hypoxia within solid adenocarcinomas and protease up-regulation has been independently implicated as poor prognostic indicators in a variety of tumor types. The authors hypothesize that Matrix Metalloproteases (MMP) are up-regulated in direct response to a hypoxic environment.

MATERIALS AND METHODS

Colonic (SW1222), breast (MDA-MB231), and pancreatic (PSN-1) tumor cell lines were exposed to hypoxia (1% oxygen/94% nitrogen/5% carbon dioxide) for periods of up to 24 h. Reaction to a hypoxic environment was determined via invasion across a Matrigel-coated 8-microm Transwell filter. Activity of MMP 2 and 9 was assessed using gelatin zymography. Expression of tissue inhibitor of metalloproteases 1 (TIMP-1) was quantified using ELISA (Biotrak). Correlation between protease expression and invasive capacity was determined using a specific gelatinase inhibitor (MMPI; Calbiochem).

RESULTS

All tumor lines demonstrated augmented invasion over 72 h (P < 0.01 all groups). Concomitant significant increase in MMP 2 and 9 activity was observed in the SW1222 and PSN-1 lines. MDA-MB231s showed increase in MMP 9 expression and in a unidentified 103-kDa gelatinase (P < 0.001). The hypoxia-augmented invasion was attenuated by the addition of a specific gelatinase inhibitor confirming interdependence.

CONCLUSIONS

Hypoxia induces an increased invasive capacity via gelatinase up-regulation without loss of cell viability. This suggests a mechanism explaining the poorer prognosis seen in patients with protease-secreting solid adenocarcinomas.

Atlas-based automatic segmentation of MR images: validation study on the brainstem in radiotherapy context

PURPOSE

Brain tumor radiotherapy requires the volume measurements and the localization of several individual brain structures. Any tool that can assist the physician to perform the delineation would then be of great help. Among segmentation methods, those that are atlas-based are appealing because they are able to segment several structures simultaneously, while preserving the anatomy topology. This study aims to evaluate such a method in a clinical context.

METHODS AND MATERIALS

The brain atlas is made of two three-dimensional (3D) volumes: the first is an artificial 3D magnetic resonance imaging (MRI); the second consists of the segmented structures in this artificial MRI. The elastic registration of the artificial 3D MRI against a patient 3D MRI dataset yields an elastic transformation that can be applied to the labeled image. The elastic transformation is obtained by minimizing the sum of the square differences of the image intensities and derived from the optical flow principle. This automatic delineation (AD) enables the mapping of the segmented structures onto the patient MRI. Parameters of the AD have been optimized on a set of 20 patients. Results are obtained on a series of 6 patients' MRI. A comprehensive validation of the AD has been conducted on performance of atlas-based segmentation in a clinical context with volume, position, sensitivity, and specificity that are compared by a panel of seven experimented physicians for the brain tumor treatments.

RESULTS

Expert interobserver volume variability ranged from 16.70 cm(3) to 41.26 cm(3). For patients, the ratio of minimal to maximal volume ranged from 48% to 70%. Median volume varied from 19.47 cm(3) to 27.66 cm(3) and volume of the brainstem calculated by AD varied from 17.75 cm(3) to 24.54 cm(3). Medians of experts ranged, respectively, for sensitivity and specificity, from 0.75 to 0.98 and from 0.85 to 0.99. Median of AD were, respectively, 0.77 and 0.97. Mean of experts ranged, respectively, from 0.78 to 0.97 and from 0.86 to 0.99. Mean of AD were, respectively, 0.76 and 0.97.

CONCLUSIONS

Results demonstrate that the method is repeatable, provides a good trade-off between accuracy and robustness, and leads to reproducible segmentation and labeling. These results can be improved by enriching the atlas with the rough information of tumor or by using different laws of deformation for the different structures. Qualitative results also suggest that this method can be used for automatic segmentation of other organs such as neck, thorax, abdomen, pelvis, and limbs.

Effects of nicotinamide and carbogen in different murine colon carcinomas: Immunohistochemical analysis of vascular architecture and microenvironmental parameters

PURPOSE

To investigate oxygenation, perfusion, and cell proliferation in two murine colon carcinoma lines with known differences in chemotherapy sensitivity and analyze the effect of nicotinamide and carbogen on these tumor characteristics.

METHODS AND MATERIALS

Mice with s.c. transplanted C38 and C26a murine colon tumors were treated with nicotinamide and carbogen and compared with control tumors. Two markers of hypoxia, CCI-103F and pimonidazole, were injected before and after treatment with nicotinamide/carbogen, respectively, allowing each tumor to serve as its own control. Hoechst33342 was used as a perfusion marker and bromodeoxyuridine (BrdUrd) as a proliferation marker. Frozen tumors were cut for multistep immunostaining and computer-controlled microscope scanning for hypoxic fractions (HF), perfused fractions (PF), vascular density, and BrdUrd-labeling index (LI).

RESULTS

Microscopic observation of C38 and C26a tumors showed extensive differences in vascular architecture, distribution patterns of hypoxia, and BrdUrd-labeling. Quantitative analysis of C38 and C26a tumors showed a decrease in HF in response to all treatment modalities. For C38 tumors, the average decrease in HF in response to carbogen containing treatments was larger than to nicotinamide alone. In C26a tumors, no difference in average decrease in HF was observed between the treatments. The PF of C38 and C26a did not change in response to treatment. The LI of C38 and C26a decreased upon all treatments, which was statistically significant in the combination treatment of C38.

CONCLUSIONS

The mechanism that can simultaneously explain all the observed changes in response to treatment may be the conversion of metabolism from less respiration toward more glycolysis due to increased glucose levels (Crabtree effect), although other mechanisms of actions cannot be excluded.

Clinical studies of hypoxia modification in radiotherapy

Hypoxic modification has been the subject of investigations in clinical radiation oncology since the early 60s. To date, this has not yet resulted in a treatment that has been widely accepted. Logistics and technical difficulties limit the routine use of hyperbaric oxygen in radiotherapy. The nitroimidazoles have not gained general acceptance, initially because of their toxicity and later because of doubts about the effectiveness of the newer generation of less toxic drugs. Nevertheless, there is good evidence from these studies that improving clinical outcome by hypoxic modulation is an achievable goal. Newer approaches including combinations of radiotherapy with tirapazamine, erythropoietin, and carbogen and nicotinamide (ARCON) are currently in phase III trial. For these new strategies to be successful, it is important that the proper patient categories are selected. Various methods to assess tumor oxygenation are now becoming available in the clinic. These potential predictive assays must be incorporated and validated in current and future large-scale clinical trials. Modifiers that target other aspects of tumor biology may also have indirect effects on tumor oxygenation. These aspects require further study in preclinical and early clinical settings.

External beam and conformal radiotherapy in the management of gliomas

External beam radiotherapy remains an important local treatment modality in both high and low grade gliomas, however its contribution to outcome remains modest. In high grade tumours this is because of their extreme clinical radioresistance, with local recurrences occurring even after doses over 70 Gy. In low grade tumours radiation does not seem to alter the overall pattern of disease progression significantly. Therefore despite use of the new technologies now available that allow radiotherapy to be delivered more accurately and to higher doses, local control of these tumours is still rarely achieved. Unfortunately these tumours have not proven sensitive to changes in radiotherapy fractionation or to the addition of radiosensitising agents. Novel approaches to these tumours are needed, based on an improved understanding of both tumour and normal tissue response to radiation.

How to overcome (and exploit) tumor hypoxia for targeted gene therapy

Tumor hypoxia has long been recognized as a critical issue in oncology. Resistance of hypoxic areas has been shown to affect treatment outcome after radiation, chemotherapy, and surgery in a number of tumor sites. Two main strategies to overcome tumor hypoxia are to increase the delivery of oxygen (or oxygen-mimetic drugs), and exploiting this unique environmental condition of solid tumors for targeted therapy. The first strategy includes hyperbaric oxygen breathing, the administration of carbogen and nicotinamide, and the delivery of chemical radiosensitizers. In contrast, bioreductive drugs and hypoxia-targeted suicide gene therapy aim at activating cytotoxic agents at the tumor site, while sparing normal tissue from damage. The cellular machinery responds to hypoxia by activating the expression of genes involved in angiogenesis, anaerobic metabolism, vascular permeability, and inflammation. In most cases, transcription is initiated by the binding of the transcription factor hypoxia-inducible factor (HIF) to hypoxia responsive elements (HREs). Hypoxia-targeting for gene therapy has been achieved by utilizing promoters containing HREs, to induce selective and efficient transgene activation at the tumor site. Hypoxia-targeted delivery and prodrug activation may add additional levels of selectivity to the treatment. In this article, the latest developments of cancer gene therapy of the hypoxic environment are discussed, with particular attention to combined protocols with ionizing radiation. Ultimately, it is proposed that by adopting specific transgene activation and molecular amplification systems, resistant hypoxic tumor tissues may be effectively targeted with gene therapy.