Phase III randomized study of radiotherapy plus procarbazine, lomustine, and vincristine with or without BUdR for treatment of anaplastic astrocytoma: final report of RTOG 9404

Pathways of the Dissociative Electron Attachment Observed in 5- and 6-Azidomethyluracil Nucleosides: Nitrogen (N2) Elimination vs Azide Anion (N3-) Elimination

5-Azidomethyl-2'-deoxyuridine (5-AmdU, 1) has been successfully employed for the metabolic labeling of DNA and fluorescent imaging of live cells. 5-AmdU also demonstrated significant radiosensitization in breast cancer cells via site-specific nitrogen-centered radical (π-aminyl (U-5-CH2-NH•), 2, and σ-iminyl (U-5-CH═N•), 3) formation. This work shows that these nitrogen-centered radicals are not formed via the reduction of the azido group in 6-azidomethyluridine (6-AmU, 4). Radical assignments were performed using electron spin resonance (ESR) in supercooled solutions, pulse radiolysis in aqueous solutions, and theoretical (DFT) calculations. Radiation-produced electron addition to 4 leads to the facile N3- loss, forming a stable neutral C-centered allylic radical (U-6-CH2•, 5) through dissociative electron attachment (DEA) via the transient negative ion, TNI (U-6-CH2-N3•-), in agreement with DFT calculations. In contrast, TNI (U-5-CH2-N3•-) of 1, via facile N2 loss (DEA) and protonation from the surrounding water, forms radical 2. Subsequently, 2 undergoes rapid H-atom abstraction from 1 and produces the metastable intermediate α-azidoalkyl radical (U-5-CH•-N3). U-5-CH•-N3 converts facilely to radical 3. N3- loss from U-6-CH2-N3•- is thermodynamically controlled, whereas N2 loss from U-5-CH2-N3•- is dictated by protonation from the surrounding waters and resonance conjugation of the azidomethyl side chain at C5 with the pyrimidine ring.

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.

Quasi-Free Electron-Mediated Radiation Sensitization by C5-Halopyrimidines

Substitution of the thymidine moiety in DNA by C5-substituted halogenated thymidine analogues causes significant augmentation of radiation damage in living cells. However, the molecular pathway involved in such radiosensitization process has not been clearly elucidated to date in solution at room temperature. So far, low-energy electrons (LEEs; 0-20 eV) under vacuum condition and solvated electrons (esol-) in solution are shown to produce the σ-type C5-centered pyrimidine base radical through dissociative electron attachment involving carbon-halogen bond breakage. Formation of this σ-type radical and its subsequent reactions are proposed to cause cellular radiosensitization. Here, we report time-resolved measurements at room temperature, showing that a radiation-produced quasi-free electron (eqf-) in solution promptly breaks the C5-halogen bond in halopyrimidines forming the σ-type C5 radical via an excited transient anion radical. These results demonstrate the importance of ultrafast reactions of eqf-, which are extremely important in chemistry, physics, and biology, including tumor radiochemotherapy.

Changes in cytoarchitecture and mobility in B16F1 melanoma cells induced by 5-Br-2'-dU coincide with Rock2, miRNAs 138-5p and 455-3p reciprocal expressions

ROCK2 is a protein involved in the restructuring of the cytoskeleton in cell adhesion and contractibility processes. miR-138-5p and miR-455-3p regulate Rock2 expression, cell proliferation, migration, and invasion in different experimental cell models. However, their participation in the cytoarchitecture and mobility of B16F1 melanoma cells exposed to 5-Br-2'-dU is partially known. This work aimed to analyze ROCK2 and miRs 138-5p and 455-3p expression associated with morphological and mobility changes of B16F1 mouse melanoma cells exposed to the thymidine analog 5-Bromo-2'-deoxyuridine (5-Br-2'-dU). We observed an increase (2.2X n = 3, p < 0.05) in the cell area, coinciding with an increase in cell diameter (1.27X n = 3, p < 0.05), as well as greater cell granularity, capacity for circularization, adhesion, which was associated with more significant polymerization of F-actin, collapsed in the intermediate filaments of vimentin (VIM), and coinciding with a decrease in migration (87%). Changes coincided with a decrease in Rock2 mRNA expression (2.88X n = 3, p < 0.05), increased vimentin and a reciprocal decrease in miR-138-5p (1.8X), and an increase in miR-455-3p (2.39X). The Rock2 kinase inhibitor Y27632 partially rescued these changes. These results suggest ROCK2 and VIM regulate the morphological and mobility changes of B16 melanoma cells after exposure to 5-Br-2'-dU, and its expression may be reciprocally regulated, at least in part, by miR-138-5p and miR-455-3p.

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.

18Oxygen Substituted Nucleosides Combined with Proton Beam Therapy: Therapeutic Transmutation In Vitro

Purpose

Proton therapy precisely delivers radiation to cancers to cause damaging strand breaks to cellular DNA, kill malignant cells, and stop tumor growth. Therapeutic protons also generate short-lived activated nuclei of carbon, oxygen, and nitrogen atoms in patients as a result of atomic transmutations that are imaged by positron emission tomography (PET). We hypothesized that the transition of ¹⁸O to ¹⁸F in an ¹⁸O-substituted nucleoside irradiated with therapeutic protons may result in the potential for combined diagnosis and treatment for cancer with proton therapy.

Materials and Methods

Reported here is a feasibility study with a therapeutic proton beam used to irradiate H₂¹⁸O to a dose of 10 Gy produced by an 85 MeV pristine Bragg peak. PET imaging initiated >45 minutes later showed an ¹⁸F decay signal with T_1/2 of ∼111 minutes.

Results

The ¹⁸O to ¹⁸F transmutation effect on cell survival was tested by exposing SQ20B squamous carcinoma cells to physiologic ¹⁸O-thymidine concentrations of 5 μM for 48 hours followed by 1- to 9-Gy graded doses of proton radiation given 24 hours later. Survival analyses show radiation sensitization with a dose modification factor (DMF) of 1.2.

Conclusions

These data support the idea of therapeutic transmutation in vitro as a biochemical consequence of proton activation of ¹⁸O to ¹⁸F in substituted thymidine enabling proton radiation enhancement in a cancer cell. ¹⁸O-substituted molecules that incorporate into cancer targets may hold promise for improving the therapeutic window of protons and can be evaluated further for postproton therapy PET imaging.

Caregiver perceptions of end-of-life care in patients with high-grade glioma

Background

Patients dying from high-grade gliomas (HGG) suffer from high symptom burden in the end-of-life (EoL) phase. Family caregivers are most informed about the patient's symptoms and disease course. The aim of this study is to assess caregiver perception on quality of EoL care of HGG patients.

Methods

Caregivers prospectively participated in the Toolkit After-Death Bereaved Family Member Interview, part of the Toolkit of Instruments to Measure End-of-Life Care (TIME survey). This validated survey assesses EoL care in areas such as physical comfort and emotional support, advance care planning, focus on the individual, attention to family, and coordination of care. The quality of EoL care was measured by domain scores (0 = care was always optimal, 1 = care was always suboptimal) or with a 0-10 scale.

Results

Of the 55 enrolled family caregivers, 44 completed the interview and rated the overall care high (8.90 ± 1.36/10), perceived that patients' wishes were respected (9.46 ± 0.95) and that they died in dignity (9.65 ± 0.98). Caregivers perceived high satisfaction with information and decision-making (0.18), advance care planning (0.19), focus on the individual (0.16), and care coordination (0.11). Attention to family (0.25) needed improvement. Only 41% of caregivers were confident that they knew what to do at the time of death and 46% felt that the healthcare team did not provide them with someone to turn to in distress.

Conclusions

Caregivers reported high overall satisfaction with EoL HGG care, though attention to family and communication needed improvement. Focus should therefore be on improved caregiver communication to improve EoL care, caregiver burnout, and bereavement in HGG populations.

Kinetics of molecular decomposition under irradiation of gold nanoparticles with nanosecond laser pulses-A 5-Bromouracil case study

Laser illuminated gold nanoparticles (AuNPs) efficiently absorb light and heat up the surrounding medium, leading to versatile applications ranging from plasmonic catalysis to cancer photothermal therapy. Therefore, an in-depth understanding of the thermal, optical, and electron induced reaction pathways is required. Here, the electrophilic DNA nucleobase analog 5-Bromouracil (BrU) has been used as a model compound to study its decomposition in the vicinity of AuNPs illuminated with intense ns laser pulses under various conditions. The plasmonic response of the AuNPs and the concentration of BrU and resulting photoproducts have been tracked by ultraviolet and visible (UV-Vis) spectroscopy as a function of the irradiation time. A kinetic model has been developed to determine the reaction rates of two parallel fragmentation pathways of BrU, and their dependency on laser fluence and adsorption on the AuNP have been evaluated. In addition, the size and the electric field enhancement of the decomposed AuNPs have been determined by atomic force microscopy and finite domain time difference calculations, respectively. A minor influence of the direct photoreaction and a strong effect of the heating of the AuNPs have been revealed. However, due to the size reduction of the irradiated AuNPs, a trade-off between laser fluence and plasmonic response of the AuNPs has been observed. Hence, the decomposition of the AuNPs might be limiting the achievable temperatures under irradiation with several laser pulses. These findings need to be considered for an efficient design of catalytic plasmonic systems.

Pulsed Reduced Dose Rate Radiotherapy in Conjunction With Bevacizumab or Bevacizumab Alone in Recurrent High-grade Glioma: Survival Outcomes

Purpose:

Dismal prognosis and limited treatment options for recurrent high-grade glioma have provoked interest in various forms of reirradiation. Pulsed reduced dose rate radiation therapy (pRDR) is a promising technique that exploits low-dose hyper-radiosensitivity of proliferating tumor cells while sparing adjacent nonproliferating normal brain tissue. Large radiation treatment volumes can thus be used to target both contrast-enhancing and FLAIR abnormalities thought to harbor recurrent gross and microscopic disease, respectively. The aim of this retrospective study was to determine whether the addition of pRDR to bevacizumab improves survival over bevacizumab alone for recurrent high-grade glioma.

Methods and Materials:

Eighty patients with recurrent high-grade glioma were included in this study; 47 patients received bevacizumab monotherapy (BEV), and 33 patients received pRDR with bevacizumab (BEV/pRDR). Progression-free survival (PFS) and overall survival were compared between the BEV and BEV/pRDR groups. Regression analysis was performed to identify and control for confounding influences on survival analyses.

Results:

Significant (P <.05) advantages in PFS (12 vs 4 months; hazard ratio = 2.37) and OS (16 vs. 9 months; hazard ratio = 1.68) were observed with BEV/pRDR compared with BEV alone.

Conclusions:

This retrospective analysis suggests that treatment with pRDR in addition to bevacizumab could significantly prolong PFS and overall survival compared with bevacizumab alone for recurrent high-grade glioma.

Concurrent and Adjuvant Temozolomide for Newly Diagnosed Grade III Gliomas without 1p/19q Co-deletion: A Randomized, Open-Label, Phase 2 Study (KNOG-1101 Study)

Purpose

We investigated the efficacy of temozolomide during and after radiotherapy in Korean adults with anaplastic gliomas without 1p/19q co-deletion.

Materials and Methods

This was a randomized, open-label, phase 2 study and notably the first multicenter trial for Korean grade III glioma patients. Eligible patients were aged 18 years or older and had newly diagnosed non-co-deleted anaplastic glioma with an Eastern Cooperative Oncology Group performance status of 0-2. Patients were randomized 1:1 to receive radiotherapy alone (60 Gy in 30 fractions of 2 Gy) (control group, n=44) or to receive radiotherapy with concurrent temozolomide (75 mg/m²/day) followed by adjuvant temozolomide (150-200 mg/m²/day for 5 days during six 28-day cycles) (treatment group, n=40). The primary end-point was 2-year progression-free survival (PFS). Seventy patients (83.3%) were available for the analysis of the isocitrate dehydrogenase 1 gene (IDH1) mutation status.

Results

The two-year PFS was 42.2% in the treatment group and 37.2% in the control group. Overall survival (OS) did not reach to significant difference between the groups. In multivariable analysis, age was a significant risk factor for PFS (hazard ratio [HR], 2.08; 95% confidence interval [CI], 1.04 to 4.16). The IDH1 mutation was the only significant prognostic factor for PFS (HR, 0.28; 95% CI, 0.13 to 0.59) and OS (HR, 0.19; 95% CI, 0.07 to 0.50). Adverse events over grade 3 were seen in 16 patients (40.0%) in the treatment group and were reversible.

Conclusion

Concurrent and adjuvant temozolomide in Korean adults with newly diagnosed non-co- deleted anaplastic gliomas showed improved 2-year PFS. The survival benefit of this regimen needs further analysis with long-term follow-up at least more than 10 years.

DIVERSet JAG Compounds Inhibit Topoisomerase II and Are Effective Against Adult and Pediatric High-Grade Gliomas

High-grade gliomas (HGGs) are aggressive primary brain tumors with local invasive growth and poor clinical prognosis in both adult and pediatric patients. Clinical response is compounded by resistance to standard frontline antineoplastic agents, an absence of novel therapeutics, and poor in vitro models to evaluate these. We screened a range of recently identified anticancer compounds in conventional adult, pediatric, and new biopsy-derived HGG models. These in vitro lines showed a range of sensitivity to standard chemotherapeutics, with varying expression levels of the prognostic markers hypoxia-induced factor (HIF) 1α and p53. Our evaluation of lead DIVERSet library compounds identified that JAG-6A, a compound that was significantly more potent than temozolomide or etoposide, was effective against HGG models in two-dimensional and three-dimensional systems; mediated this response by the potent inhibition of topoisomerase Iiα; remained effective under normoxic and hypoxic conditions; and displayed limited toxicity to non-neoplastic astrocytes. These data suggest that JAG-6A could be an alternative topoisomerase IIα inhibitor and used for the treatment of HGG.

Outcomes for Anaplastic Glioma Treated With Radiation Therapy With or Without Concurrent Temozolomide

OBJECTIVES

Postoperative management of anaplastic glioma remains without a clear standard of care-in this study we report outcomes for patients treated with radiotherapy (RT) with and without temozolomide (TMZ).

MATERIALS AND METHODS

We identified 71 consecutive patients with World Health Organization grade III glioma treated with either RT alone or with concurrent TMZ (RT+TMZ), between 2000 and 2013. Tumor histology was anaplastic astrocytoma in 42 patients, anaplastic oligodendroglioma in 25 patients, and anaplastic oligoastrocytoma in 4 patients. In total, 26 patients received RT and 45 received RT+TMZ. Adjuvant TMZ was administered to 12/26 (46.1%) patients who received RT and 42/45 (93.3%) patients who received RT+TMZ. Time-to-event endpoints included progression-free survival (PFS) and overall survival (OS).

RESULTS

Kaplan-Meier estimates revealed that patients receiving RT+TMZ followed by adjuvant TMZ had improved PFS (P=0.04) and OS (P=0.02) as compared with those receiving RT followed by adjuvant TMZ. Cox proportional hazards multivariate analysis revealed improved PFS and OS with RT+TMZ for all patients (PFS: hazard ratio [HR]=0.42, P=0.02; OS: HR=0.41, P=0.03) and for anaplastic astrocytoma patients (PFS: HR=0.35, P=0.03; OS: HR=0.26, P=0.01), regardless of whether patients received further adjuvant TMZ.

CONCLUSIONS

These findings support the use of RT+TMZ in the postoperative management of grade III glioma, and suggest that there is a benefit to concurrent RT+TMZ that is independent of adjuvant monthly TMZ. Further investigation is warranted, both to prospectively validate the benefit of RT+TMZ, as well as to determine if an additional benefit truly exists for adjuvant TMZ following concurrent RT+TMZ.

The Physico-Chemical Basis of DNA Radiosensitization: Implications for Cancer Radiation Therapy

High-energy radiation is used in combination with radiosensitizing therapeutics to treat cancer. The most common radiosensitizers are halogenated nucleosides and cisplatin derivatives, and recently also metal nanoparticles have been suggested as potential radiosensitizing agents. The radiosensitizing action of these compounds can at least partly be ascribed to an enhanced reactivity towards secondary low-energy electrons generated along the radiation track of the high-energy primary radiation, or to an additional emission of secondary reactive electrons close to the tumor tissue. This is referred to as physico-chemical radiosensitization. In this Concept article we present current experimental methods used to study fundamental processes of physico-chemical radiosensitization and discuss the most relevant classes of radiosensitizers. Open questions in the current discussions are identified and future directions outlined, which can lead to optimized treatment protocols or even novel therapeutic concepts.

Formation of pyrimidine-pyrimidine type DNA intrastrand cross-links: a theoretical verification

Pyrimidine-type radicals have been demonstrated to be able to attack their 3' or 5' neighboring purine nucleotides forming diverse DNA intrastrand cross-links, but whether or not these radicals can attack their surrounding pyrimidine nucleotides forming pyrimidine-pyrimidine type DNA intrastrand cross-links remains unclear. To resolve this question, probable additions of the uracil-5-methyl (˙U_CH2) radical to the C₅[double bond, length as m-dash]C₆ double bond of its 3'/5' neighboring pyrimidine nucleotides in the four models, 5'-T(˙U_CH2)-3', 5'-C(˙U_CH2)-3', 5'-(˙U_CH2)T-3', and 5'-(˙U_CH2)C-3', are explored in the present work employing density functional theory (DFT) methods. The C₆ site of its 5' neighboring thymidine is the preferred target for ˙U_CH2 radical addition, while additions of the ˙U_CH2 radical to the C₆ and C₅ sites of its 5' neighboring deoxycytidine are found to be competitive reactions. The ˙U_CH2 radical can react with both the C₆ and C₅ sites of its 3' neighboring pyrimidine nucleotides, but the efficiencies of these reactions are predicted to be much lower than those of the corresponding addition reactions to its 5' neighboring pyrimidine nucleotides, indicating the existence of an obvious sequence effect. All the addition products could be finally transformed into closed-shell intrastrand cross-links, the molecular masses of which are found to be exactly the same as certain MS values determined in a recent study of an X-irradiated deoxygenated aqueous solution of calf thymus DNA. The present study thus not only definitely corroborates the fact that the reactive ˙U_CH2 radical can attack its 3'/5' neighboring pyrimidine nucleotides forming several pyrimidine-pyrimidine type DNA intrastrand cross-links, but also provides a plausible explanation for the identities of these structurally unknown intrastrand cross-links.

The Exploitation of Low-Energy Electrons in Cancer Treatment

Given the distinct characteristics of low-energy electrons (LEEs), particularly at energies less than 30 eV, they can be applied to a wide range of therapeutic modalities to improve cancer treatment. LEEs have been shown to efficiently produce complex molecular damage resulting in substantial cellular toxicities. Since LEEs are produced in copious amounts from high-energy radiation beam, including photons, protons and ions; the control of LEE distribution can potentially enhance the therapeutic radio of such beams. LEEs can play a substantial role in the synergistic effect between radiation and chemotherapy, particularly halogenated and platinum-based anticancer drugs. Radiosensitizing entities containing atoms of high atomic number such as gold nanoparticles can be a source of LEE production if high-energy radiation interacts with them. This can provide a high local density of LEEs in a cell and produce cellular toxicity. Auger-electron-emitting radionuclides also create a high number of LEEs in each decay, which can induce lethal damage in a cell. Exploitation of LEEs in cancer treatment, however, faces a few challenges, such as dosimetry of LEEs and selective delivery of radiosensitizing and chemotherapeutic molecules close to cellular targets. This review first discusses the rationale for utilizing LEEs in cancer treatment by explaining their mechanism of action, describes theoretical and experimental studies at the molecular and cellular levels, then discusses strategies for achieving modification of the distribution and effectiveness of LEEs in cancerous tissue and their associated clinical benefit.

Anaplastic astrocytoma: prognostic factors and survival in 4807 patients with emphasis on receipt and impact of adjuvant therapy

To determine the receipt and impact of adjuvant therapy on overall survival (OS) for anaplastic astrocytoma (AA). Data were extracted from the National Cancer Data Base (NCDB). Chi square test, Kaplan-Meier method, and Cox regression models were employed in SPSS 22.0 (Armonk, NY: IBM Corp.) for data analyses. 4807 patients with AA diagnosed from 2004 to 2013 who underwent surgery were identified. 3243 (67.5 %) received adjuvant chemoRT, 525 (10.9 %) adjuvant radiotherapy (RT) alone, 176 (3.7 %) adjuvant chemotherapy alone and 863 (18.0 %) received no adjuvant therapy. Patients were more likely to receive adjuvant chemoRT if they were diagnosed in 2009-2013 (p = 0.022), were ≤ 50 years (p < 0.001), were male (p = 0.043), were Asian or White race (p < 0.001), had private insurance (p < 0.001), had income ≥$38,000 (p < 0.001), or underwent total resection (p < 0.003). Those who received adjuvant chemoRT had significantly better 5-year OS than the other adjuvant treatment types (41.8 % vs. 31.2 % vs. 29.8 % vs. 27.4 %, p < 0.001). This significant 5-year OS benefit was also observed regardless of age at diagnosis. Of those undergoing adjuvant chemoRT, those receiving ≥59.4 Gy had significantly better 5-year OS than those receiving <59.4 Gy (44.4 % vs. 25.9 %, p < 0.001). There was no significant difference in OS when comparing 59.4 Gy to higher RT doses. On multivariate analysis, receipt of adjuvant chemoRT, age at diagnosis, extent of disease, and insurance status were independent prognostic factors for OS. Adjuvant chemoRT is an independent prognostic factor for improved OS in AA and concomitant chemoRT should be considered for all clinically suitable patients who have undergone surgery for the disease.

CNS Anticancer Drug Discovery and Development Conference White Paper

Following the first CNS Anticancer Drug Discovery and Development Conference, the speakers from the first 4 sessions and organizers of the conference created this White Paper hoping to stimulate more and better CNS anticancer drug discovery and development. The first part of the White Paper reviews, comments, and, in some cases, expands on the 4 session areas critical to new drug development: pharmacological challenges, recent drug approaches, drug targets and discovery, and clinical paths. Following this concise review of the science and clinical aspects of new CNS anticancer drug discovery and development, we discuss, under the rubric "Accelerating Drug Discovery and Development for Brain Tumors," further reasons why the pharmaceutical industry and academia have failed to develop new anticancer drugs for CNS malignancies and what it will take to change the current status quo and develop the drugs so desperately needed by our patients with malignant CNS tumors. While this White Paper is not a formal roadmap to that end, it should be an educational guide to clinicians and scientists to help move a stagnant field forward.

Development of a transplantable glioma tumour model from genetically engineered mice: MRI/MRS/MRSI characterisation

The initial aim of this study was to generate a transplantable glial tumour model of low-intermediate grade by disaggregation of a spontaneous tumour mass from genetically engineered models (GEM). This should result in an increased tumour incidence in comparison to GEM animals. An anaplastic oligoastrocytoma (OA) tumour of World Health Organization (WHO) grade III was obtained from a female GEM mouse with the S100β-v-erbB/inK4a-Arf (+/-) genotype maintained in the C57BL/6 background. The tumour tissue was disaggregated; tumour cells from it were grown in aggregates and stereotactically injected into C57BL/6 mice. Tumour development was followed using Magnetic Resonance Imaging (MRI), while changes in the metabolomics pattern of the masses were evaluated by Magnetic Resonance Spectroscopy/Spectroscopic Imaging (MRS/MRSI). Final tumour grade was evaluated by histopathological analysis. The total number of tumours generated from GEM cells from disaggregated tumour (CDT) was 67 with up to 100 % penetrance, as compared to 16 % in the local GEM model, with an average survival time of 66 ± 55 days, up to 4.3-fold significantly higher than the standard GL261 glioblastoma (GBM) tumour model. Tumours produced by transplantation of cells freshly obtained from disaggregated GEM tumour were diagnosed as WHO grade III anaplastic oligodendroglioma (ODG) and OA, while tumours produced from a previously frozen sample were diagnosed as WHO grade IV GBM. We successfully grew CDT and generated tumours from a grade III GEM glial tumour. Freezing and cell culture protocols produced progression to grade IV GBM, which makes the developed transplantable model qualify as potential secondary GBM model in mice.

Electrophilic 5-Substituted Uracils as Potential Radiosensitizers: A Density Functional Theory Study

Although 5-bromo-2'-deoxyuridine (5BrdU) possesses significant radiosensitizing power in vitro, clinical studies do not confirm any advantages of radiotherapy employing 5BrdU. This situation calls for a continuous search for efficient radiosensitizers. Using the proposed mechanism of radiosensitization by 5BrdU, we propose a series of 5-substituted uracils, XYU, that should undergo efficient dissociative electron attachment. The DFT-calculated thermodynamic and kinetic data concerning the XYU degradations induced by electron addition suggests that some of the scrutinized derivatives have much better characteristics than 5BrdU itself. Synthesis of these promising candidates for radiosensitizers, followed by studies of their radiosensitizing properties in DNA context, and ultimately in cancer cells, are further steps to confirm their potential applicability in anticancer treatment.

Mechanisms Responsible for High Energy Radiation Induced Damage to Single-Stranded DNA Modified by Radiosensitizing 5-Halogenated Deoxyuridines

Experimental studies showed that high energy radiation induced base release and DNA backbone breaks mainly occur at the neighboring 5' nucleotide when a single-stranded DNA is modified by radiosensitizing 5-halogenated deoxyuridines. However, no mechanism can be used to interpret these experimental observations. To better understand the radiosensitivity of 5-halogenated deoxyuridines, mechanisms involving hydrogen abstraction by the uracil-5-yl radical from the C2' and C3' positions of an adjacent nucleotide separately followed by the C3'-O3' or N-glycosidic bond rupture and the P-O3' bond breakage are investigated in the DNA sequence 5'-TU(•)-3' employing density functional theory calculations in the present study. It is found that hydrogen abstractions from both positions are comparable with the one from the C2' site slightly more favorable. The N-glycosidic bond cleavage in the neighboring 5' nucleotide following the internucleotide C2'-Ha abstraction is estimated to have the lowest activation free energies, indicating that the adjacent 5' base release dominates electron induced damage to single-stranded DNA incorporated by 5-halogenated deoxyuridines. Relative to the P-O3' bond breakage after the internucleotide C3'-H abstraction, the C3'-O3' bond rupture in the neighboring 5' nucleotide following the internucleotide C2'-Ha abstraction is predicted to have a lower activation free energy, implying that single-stranded DNA backbone breaks are prone to occur at the C3'-O3' bond site. The 5'-TU(•)-3' species has substantial electron affinity and can even capture a hydrated electron, forming the 5'-TU(-)-3' anion. However, the electron induced C3'-O3' bond rupture in 5'-TU(-)-3' anion via a pathway of internucleotide proton abstraction is only minor in both the gas phase and aqueous solution. The present theoretical predictions can interpret rationally experimental observations, thereby demonstrating that the mechanisms proposed here are responsible for high energy radiation induced damage to single-stranded DNA incorporated by radiosensitizing 5-halogenated deoxyuridines. By comparing with previous results, our work proves that the radiosensitizing action of 5-bromo-2-deoxyuridine is not weaker but stronger than its isomer 6-bromo-2-deoxyuridine on the basis of the available data.

DNA Distortion Caused by Uracil-Containing Intrastrand Cross-Links

Four uracil-containing intrastrand cross-links have been detected in human cells upon UV irradiation of 5-bromouracil-containing DNA, namely 5'-G[8-5]U-3', 5'-U[5-8]G-3', 5'-A[8-5]U-3', and 5'-A[2-5]U-3'. These lesions feature unique composition and connectivity compared with other intrastrand cross-links reported in the literature. For the first time, structural information obtained using molecular dynamics (MD) simulations reveal that all four lesions distort the DNA helix, which can involve an extrahelical location of the cross-link, changes in the helical interactions of the complementary nucleotides, or disruption of hydrogen bonding in the flanking base pairs up to two positions from the cross-linked site; however, the degree of distortion varies between the cross-links, being affected by the sequence, nucleobase-nucleobase connectivity, and the purine involved. Most importantly, the relative distortion of the damaged DNA provides the first structural explanation for the observed abundances of the four uracil-containing cross-links. Furthermore, the highly distorted conformations suggest that these lesions will likely have severe implications for DNA replication and repair processes in cells.

Impact of provider level, training and gender on the utilization of palliative care and hospice in neuro-oncology: a North-American survey

Specialized palliative care (PC) services have emerged to address symptoms and provide end-of-life management for patients with brain tumors. The utilization patterns of PC in neuro-oncology are unknown. A 22-question survey was distributed to participants of the society for neuro-oncology annual meeting 2012 (n = 4487). Nonparametric methods including Wilcoxon two-sample and Kruskal-Wallis tests were used to assess differences in responses. 239 (5.3 %) evaluable responses were received; 79 % of respondents were physicians, and 17 % were nurses or midlevel providers. Forty-seven percent were medical or neuro-oncologists, 31 % neurosurgeons and 11 % radiation oncologists. Forty percent had no formal training in PC, 57 % had some formal training and 3 % completed a PC fellowship. Seventy-nine percent practiced in an academic setting. Of the respondents, 57 % referred patients to PC when symptoms required treatment and 18 % at end of life. Only 51 % of all providers felt comfortable dealing with end-of-life issues and symptoms, while 33 % did not. Fifty-one percent preferred a service named "Supportive Care" rather than "Palliative Care" (MDs > midlevel providers, p < 0.001), and 32 % felt that patient expectations for ongoing therapy hindered their ability to make PC referrals. Female gender, formal training in neuro-oncology and PC, and medical versus surgical neuro-oncology training were significantly associated with hospice referral, comfort in dealing with end-of-life issues, and ease of access to PC services. Provider level, specialty, gender, training in PC and neuro-oncology have significant impact on the utilization of PC and hospice in neuro-oncology.

International patterns of palliative care in neuro-oncology: a survey of physician members of the Asian Society for Neuro-Oncology, the European Association of Neuro-Oncology, and the Society for Neuro-Oncology

Background

Brain tumor patients have limited survival and suffer from high morbidity requiring specific symptom management. Specialized palliative care (PC) services have been developed to address these symptoms and provide end-of-life treatment. Global utilization patterns of PC in neuro-oncology are unknown.

Methods

In a collaborative effort between the Society for Neuro-Oncology (SNO), the European Association of Neuro-Oncology (EANO), and the Asian Society for Neuro-Oncology (ASNO), a 22-question survey was distributed. Wilcoxon 2-sample and Kruskal-Wallis tests were used to assess differences in responses.

Results

Five hundred fifty-two evaluable responses were received. The most significant differences were found between Asia-Oceania (AO) and Europe as well as AO and United States/Canada (USA-C). USA-C providers had more subspecialty training in neuro-oncology, but most providers had received no or minimal training in palliative care independent of region. Providers in all 3 regions reported referring patients at the onset of symptoms requiring palliation, but USA-C and European responders refer a larger total proportion of patients to PC (P < .001). Physicians in AO and Europe (both 46%) as well as 29% of USA-C providers did not feel comfortable dealing with end-of-life issues. Most USA-C patients (63%) are referred to hospice compared with only 8% and 19% in AO and Europe (P < .001), respectively.

Conclusion

This is the first report describing global differences of PC utilization in neuro-oncology. Significant differences in provider training, culture, access, and utilization were mainly found between AO and USA-C or AO and Europe. PC patterns are more similar in Europe and USA-C.

Radiotherapy and temozolomide for anaplastic astrocytic gliomas

We previously reported results of a phase II non-comparative trial that randomized patients with glioblastoma following radiotherapy to one of two different temozolomide schedules, followed by 13-cis-retinoic acid (RA) maintenance. Here we report the results of an exploratory cohort of patients accrued with anaplastic astrocytic tumors. Patients with newly diagnosed anaplastic astrocytoma (AA) or anaplastic oligo-astrocytoma (AOA) were treated with concurrent radiotherapy (60 Gy over 6 weeks) and temozolomide (75 mg/m(2)), and six adjuvant 28-day cycles of either dose-dense (150 mg/m(2), days 1-7, 15-21) or metronomic (50 mg/m(2), days 1-28) temozolomide. Subsequently, maintenance RA (100 mg/m(2), days 1-21/28) was administered until disease progression. All outcome measures were descriptive without intention to compare between treatment arms. Survival was measured by the Kaplan-Meier method. There were 31 patients (21 men, 10 women) with median age 48 years (range 28-74), median KPS 90 (range 60-100). Extent of resection was gross-total in 35%, subtotal 23%, and biopsy 42%. Histology was AA in 90%, and AOA in 10%. MGMT promoter methylation was methylated in 20%, unmethylated in 50%, and uninformative in 30% of 30 tested. Median progression-free survival was 2.1 years (95% CI 0.95-Not Reached), and overall survival 2.9 years (95 % CI 2.0-Not Reached). We report outcomes among a homogeneously treated population with anaplastic astrocytic tumors. Survival was unexpectedly short compared to other reports. These data may be useful as a contemporary historic control for other ongoing or future randomized trials.

Contemporary Review of the Management of Brain Metastasis with Radiation

Brain metastases are an important cause of morbidity and mortality, afflicting approximately 200,000 Americans annually. The prognosis for these patients is poor, with median survivals typically measured in months. In this review article, we present the standard treatment approaches with whole brain radiation and as well as novel approaches in the prevention of neurocognitive deficits.

Radiosurgical options in neuro-oncology: a review on current tenets and future opportunities. Part II: adjuvant radiobiological tools

Stereotactic radiosurgery (SRS) is currently a well-established, minimally invasive treatment for many primary and secondary tumors, especially deep-sited lesions for which traditional neurosurgical procedures were poorly satisfactory or not effective at all. The initial evolution of SRS was cautious, relying on more than 30 years of experimental and clinical work that preceded its introduction into the worldwide medical community. This path enabled a brilliant present, and the continuous pace of technological advancement holds promise for a brighter future. Part II of this review article will cover the impact of multimodal adjuvant technologies on SRS, and their input to the crucial role played by neurosurgeons, radiation oncologists and medical physicists in the management and care of fragile neuro-oncological patients.

Palliative and supportive care for glioma patients

The diagnosis of a brain tumor is a life-changing event for patients and families. High-grade gliomas are incurable and long-term survival remains limited. While low-grade glioma patients have better outcomes, their quality of life is often affected by a variety of symptoms as well. Helping glioma patients improve quality of life at all stages of illness is an important goal for the interdisciplinary care team. There is evidence from advanced lung cancer patients that early involvement of a palliative care team can improve patient's quality of life, symptom burden, and even survival and a similar approach benefits glioma patients as well. Patients with high-grade and low-grade glioma often suffer from significant symptom burden. We discuss how validated global symptom assessments and symptom-specific screening tools are useful to identify distressing symptoms. Seizures, fatigue, depression, and anxiety are some of the more common symptoms throughout the disease course and should be managed actively. Patients with glioma also have high symptom burden at the end of life and the majority lose decision-making capacity. Advance care planning conversations early in the disease course are essential to elicit the patient's wishes for end of life care and effective communication with surrogate decision makers during all stages of the disease helps ensure that those wishes are respected.

An ESR and DFT study of hydration of the 2'-deoxyuridine-5-yl radical: a possible hydroxyl radical intermediate

The mechanism of radiation-induced frank strand break formation in irradiated 5-bromo-2'-deoxyuridine (BrdU)-labelled DNA is still unclear despite the proven radiosensitizing properties of BrdU. Combination of ESR spectroscopy and quantum chemical modelling points to a simple reaction between the uridine-5-yl radical and water molecules that produces the genotoxic hydroxyl radical.

Targeting adaptive glioblastoma: an overview of proliferation and invasion

Glioblastoma is one of the most devastating cancers, in which tumor cell infiltration into surrounding normal brain tissue confounds clinical management. This review describes basic and translational research into glioma proliferation and invasion, in particular the phenotypic switch underlying a stochastic "go or grow" model of tumor cell behavior. We include recent progress in system genomics, cancer stem cell theory, and tumor-microenvironment interaction, from which novel therapeutic strategies may emerge for managing this malignant disease. We suggest that an effective therapeutic strategy should target both adaptive glioblastoma cells and the stroma-tumor interaction.

An orthotopic glioblastoma mouse model maintaining brain parenchymal physical constraints and suitable for intravital two-photon microscopy

Glioblastoma multiforme (GBM) is the most aggressive form of brain tumors with no curative treatments available to date. Murine models of this pathology rely on the injection of a suspension of glioma cells into the brain parenchyma following incision of the dura-mater. Whereas the cells have to be injected superficially to be accessible to intravital two-photon microscopy, superficial injections fail to recapitulate the physiopathological conditions. Indeed, escaping through the injection tract most tumor cells reach the extra-dural space where they expand abnormally fast in absence of mechanical constraints from the parenchyma. Our improvements consist not only in focally implanting a glioma spheroid rather than injecting a suspension of glioma cells in the superficial layers of the cerebral cortex but also in clogging the injection site by a cross-linked dextran gel hemi-bead that is glued to the surrounding parenchyma and sealed to dura-mater with cyanoacrylate. Altogether these measures enforce the physiological expansion and infiltration of the tumor cells inside the brain parenchyma. Craniotomy was finally closed with a glass window cemented to the skull to allow chronic imaging over weeks in absence of scar tissue development. Taking advantage of fluorescent transgenic animals grafted with fluorescent tumor cells we have shown that the dynamics of interactions occurring between glioma cells, neurons (e.g. Thy1-CFP mice) and vasculature (highlighted by an intravenous injection of a fluorescent dye) can be visualized by intravital two-photon microscopy during the progression of the disease. The possibility to image a tumor at microscopic resolution in a minimally compromised cerebral environment represents an improvement of current GBM animal models which should benefit the field of neuro-oncology and drug testing.

Integration of palliative care into the neuro-oncology practice: patterns in the United States

BACKGROUND

Between 80%-85 percent of all adult brain tumors are high-grade gliomas (HGGs). Despite aggressive treatment with surgical resection, radiotherapy and chemotherapy, the survival of patients with HGG is limited. Brain tumor patients develop unique symptoms and needs throughout their disease trajectory, and the majority lose the ability to communicate during the end-of-life phase. Palliative care (PC) is a proactive and systematic approach to manage issues that are important to patients and families affected by serious illness. The goal is to improve quality of life and symptom control and thereby reduce suffering. Most PC interventions take place during the end-of-life phase; however, newer data suggest that early PC interventions might improve symptom control and quality of life.

METHODS

A literature review focusing on PC, hospice care, and end-of-life care was performed with the aim to describe the integration of PC into neuro-oncology practice.

RESULTS

Recently there has been increased interest in the effects of PC and brain tumor patients. The origins, methodology, and conceptual models of delivering PC and how it might be applied to the field of neuro-oncology were reviewed. Patterns of referral and utilization in neuro-oncology are described based on the findings of a recent survey.

CONCLUSIONS

Despite a very high symptom burden, many HGG patients do not receive the same level of PC and have fewer interactions with PC services than other cancer populations. Early PC interventions and structured advance-care planning might improve symptom control and quality of life for brain tumor patients.

Electron induced single strand break and cyclization: a DFT study on the radiosensitization mechanism of the nucleotide of 8-bromoguanine

Cleavage of the O-P bond in 8-bromo-2'-deoxyguanosine-3',5'-diphosphate (BrdGDP), considered as a model of single strand break (SSB) in labelled double-stranded DNA (ds DNA), is investigated at the B3LYP/6-31++G(d,p) level. The thermodynamic and kinetic characteristics of the formation of SSB are compared to those related to the 5',8-cycloguanosine lesion. The first reaction step, common to both damage types, which is the formation of the reactive guanyl radical, proceeds with a barrier-free or low-barrier release of the bromide anion. The guanyl radical is then stabilized by hydrogen atom transfer from the C3' or C5' sites of the 2'-deoxyribose moiety to its C8 center. The C3' path, via the O-P bond cleavage, leads to a ketone derivative (the SSB model), while the C5' path is more likely to yield 5',8-cycloguanosine.

Six-color intravital two-photon imaging of brain tumors and their dynamic microenvironment

The majority of intravital studies on brain tumor in living animal so far rely on dual color imaging. We describe here a multiphoton imaging protocol to dynamically characterize the interactions between six cellular components in a living mouse. We applied this methodology to a clinically relevant glioblastoma multiforme (GBM) model designed in reporter mice with targeted cell populations labeled by fluorescent proteins of different colors. This model permitted us to make non-invasive longitudinal and multi-scale observations of cell-to-cell interactions. We provide examples of such 5D (x,y,z,t,color) images acquired on a daily basis from volumes of interest, covering most of the mouse parietal cortex at subcellular resolution. Spectral deconvolution allowed us to accurately separate each cell population as well as some components of the extracellular matrix. The technique represents a powerful tool for investigating how tumor progression is influenced by the interactions of tumor cells with host cells and the extracellular matrix micro-environment. It will be especially valuable for evaluating neuro-oncological drug efficacy and target specificity. The imaging protocol provided here can be easily translated to other mouse models of neuropathologies, and should also be of fundamental interest for investigations in other areas of systems biology.

Motexafin gadolinium: a novel radiosensitizer for brain tumors

Despite advances in the field of oncology, progress for patients with brain metastases and most primary brain tumors has been slow. New efforts to enhance the therapeutic index of radiation therapy are under way, including the use of radiosensitizers. Motexafin gadolinium (Xcytrin) is one such novel agent with several unique properties that enhance the cytotoxic potential of radiation therapy, as well as several chemotherapeutic agents, and possibly has independent cytotoxicity in certain lymphoid malignancies. Motexafin gadolinium is very well tolerated with tumor specific uptake. The rationale for the use of this drug as well as its current and future role as a radiation enhancer in the management of brain tumors is reviewed.

Enhancing radiation therapy for patients with glioblastoma

Radiation therapy has been the foundation of therapy following maximal surgical resection in patients with newly diagnosed glioblastoma for decades and the primary therapy for unresected tumors. Using the standard approach with radiation and temozolomide, however, outcomes are poor, and glioblastoma remains an incurable disease with the majority of recurrences and progression within the radiation treatment field. As such, there is much interest in elucidating the mechanisms of resistance to radiation therapy and in developing novel approaches to overcoming this treatment resistance.

Advanced MR imaging of gliomas: an update

Recent advances in the treatment of cerebral gliomas have increased the demands on noninvasive neuroimaging for the diagnosis, therapeutic planning, tumor monitoring, and patient outcome prediction. In the meantime, improved magnetic resonance (MR) imaging techniques have shown much potentials in evaluating the key pathological features of the gliomas, including cellularity, invasiveness, mitotic activity, angiogenesis, and necrosis, hence, further shedding light on glioma grading before treatment. In this paper, an update of advanced MR imaging techniques is reviewed, and their potential roles as biomarkers of tumor grading are discussed.

Current status of local therapy in malignant gliomas--a clinical review of three selected approaches

Malignant gliomas are the most frequently occurring, devastating primary brain tumors, and are coupled with a poor survival rate. Despite the fact that complete neurosurgical resection of these tumors is impossible in consideration of their infiltrating nature, surgical resection followed by adjuvant therapeutics, including radiation therapy and chemotherapy, is still the current standard therapy. Systemic chemotherapy is restricted by the blood-brain barrier, while methods of local delivery, such as with drug-impregnated wafers, convection-enhanced drug delivery, or direct perilesional injections, present attractive ways to circumvent these barriers. These methods are promising ways for direct delivery of either standard chemotherapeutic or new anti-cancer agents. Several clinical trials showed controversial results relating to the influence of a local delivery of chemotherapy on the survival of patients with both recurrent and newly diagnosed malignant gliomas. Our article will review the development of the drug-impregnated release, as well as convection-enhanced delivery and the direct injection into brain tissue, which has been used predominantly in gene-therapy trials. Further, it will focus on the use of convection-enhanced delivery in the treatment of patients with malignant gliomas, placing special emphasis on potential shortcomings in past clinical trials. Although there is a strong need for new or additional therapeutic strategies in the treatment of malignant gliomas, and although local delivery of chemotherapy in those tumors might be a powerful tool, local therapy is used only sporadically nowadays. Thus, we have to learn from our mistakes in the past and we strongly encourage future developments in this field.

Bevacizumab in high-grade gliomas: a review of its uses, toxicity assessment, and future treatment challenges

High-grade gliomas continue to have dismal prognosis despite advances made in understanding the molecular genetics, signaling pathways, cytoskeletal dynamics, and the role of stem cells in gliomagenesis. Conventional treatment approaches, including surgery, radiotherapy, and cytotoxic chemotherapy, have been used with limited success. Therapeutic advances using molecular targeted therapy, immunotherapy, and others such as dietary treatments have not been able to halt tumor progression and disease-related death. High-grade gliomas (World Health Organization grades III/IV) are histologically characterized by cellular and nuclear atypia, neoangiogenesis, and necrosis. The expression of vascular endothelial growth factor, a molecular mediator, plays a key role in vascular proliferation and tumor survival. Targeting vascular endothelial growth factor has demonstrated promising results, with improved quality of life and progression-free survival. Bevacizumab, a humanized monoclonal antibody to vascular endothelial growth factor, is approved by the Food and Drug Administration as a single agent in recurrent glioblastoma and is associated with manageable toxicity. This review discusses the efficacy, practical aspects, and response assessment challenges with the use of bevacizumab in the treatment of high-grade gliomas.

Angiogenic inhibition in high-grade gliomas: past, present and future

High-grade gliomas, especially glioblastoma (GBM), are among the most aggressive and vascularized tumors. Angiogenesis plays a significant role in tumor growth and survival, and thus offers a target for anticancer treatment. Bevacizumab, a humanized monoclonal antibody against VEGF, was approved by the US FDA as a single agent for the treatment of recurrent glioblastoma. Significant radiographic response and progression-free survival were seen with bevacizumab treatment. However, benefits to overall survival remain undetermined. Other antiangiogenic strategies targeting VEGF, VEGF receptor (VEGFR) and other angiogenic factors have also been examined. Tumor progression after antiangiogenic treatment is inevitable, and effective salvage therapy is yet to be identified. Mechanisms of resistance to antiangiogenic therapy include activation of alternative proangiogenic pathways and increased tumor invasion. Strategies targeting these escape mechanisms are currently being investigated. The use of antiangiogenic drugs is generally well tolerated, although rare and potentially life-threatening adverse effects have been identified. With the striking antipermeability effect of anti-VEGF inhibitors, assessment of true tumor response has become a challenge. The Response Assessment in Neuro-Oncology Working Group has developed new criteria for clinical trials in patients with high-grade glioma. Identification of neuroimaging advances and biologic markers will greatly enhance treatment strategies for these patients.

Management of treatment-associated toxicites of anti-angiogenic therapy in patients with brain tumors

Anti-angiogenic therapies, including bevacizumab, are being used with increasing frequency in the management of malignant glioma. Common clinically significant toxicities include hypertension and proteinuria, poor wound healing, and the potential for thromboembolic events. Literature related to the use of bevacizumab in malignant glioma, reported toxicities in this patient population, and management of these toxicities was reviewed. Recommendations for assessment and management are provided. Anti-angiogenic therapies will continue to have a role in the treatment of malignant glioma. Further studies of the prevention, assessment, and management of these toxicities are warranted.

The prognostic value of IDH mutations and MGMT promoter status in secondary high-grade gliomas

Reports about the prognostic value of IDH mutations and the promoter region of the O6-Methyl-guanyl-methyl-transferase gene in secondary high-grade gliomas (sHGG) are few in number. We investigated the prognostic value of IDH mutations and methylation of the promoter region of the MGMT gene in 99 patients with sHGG and analyzed the clinical course of those tumors. Patients with sHGG were screened for IDH mutations by direct sequencing, and, for promoter status of MGMT gene, by the methylation-specific polymerase chain reaction. A total of 48 of 99 patients (48.5 %) had secondary anaplastic gliomas (Group 1), while 51 patients had secondary glioblastomas (Group 2). The median survival time after malignant progression of all patients with sHGG and with an IDH mutation was 4 years, which is significantly longer than in patients with wild-type IDH (1.2 years, p = 0.009). Patients' survival was not significantly influenced by the tumors' MGMT promoter status, both in Group 1- 9.7 years vs. 6.1 years, methylated vs. unmethylated promoter (p = 0.330)-as well as in Group 2-1.5 years vs. 1.6 years, methylated versus unmethylated promoter (p = 0.829). In our population, the IDH mutation status was not associated with increased PFS or median survival time in sGBM patients. However, patients with secondary anaplastic glioma and IDH mutation had a significantly improved outcome. In addition, IDH mutations are a more powerful prognostic marker concerning both PFS and MS than the MGMT promoter status in those patients.