Linking epigenetic signature and metabolic phenotype in IDH mutant and IDH wildtype diffuse glioma.

AIMS: Changes in metabolism are known to contribute to tumour phenotypes. If and how metabolic alterations in brain tumours contribute to patient outcome is still poorly understood. Epigenetics impact metabolism and mitochondrial function. The aim of this study is a characterisation of metabolic features in molecular subgroups of isocitrate dehydrogenase mutant (IDHmut) and isocitrate dehydrogenase wildtype (IDHwt) gliomas. METHODS: We employed DNA methylation pattern analyses with a special focus on metabolic genes, large-scale metabolism panel immunohistochemistry (IHC), qPCR-based determination of mitochondrial DNA copy number and immune cell content using IHC and deconvolution of DNA methylation data. We analysed molecularly characterised gliomas (n = 57) for in depth DNA methylation, a cohort of primary and recurrent gliomas (n = 22) for mitochondrial copy number and validated these results in a large glioma cohort (n = 293). Finally, we investigated the potential of metabolic markers in Bevacizumab (Bev)-treated gliomas (n = 29). RESULTS: DNA methylation patterns of metabolic genes successfully distinguished the molecular subtypes of IDHmut and IDHwt gliomas. Promoter methylation of lactate dehydrogenase A negatively correlated with protein expression and was associated with IDHmut gliomas. Mitochondrial DNA copy number was increased in IDHmut tumours and did not change in recurrent tumours. Hierarchical clustering based on metabolism panel IHC revealed distinct subclasses of IDHmut and IDHwt gliomas with an impact on patient outcome. Further quantification of these markers allowed for the prediction of survival under anti-angiogenic therapy. CONCLUSION: A mitochondrial signature was associated with increased survival in all analyses, which could indicate tumour subgroups with specific metabolic vulnerabilities.

Gliomatosis Cerebri Growth Pattern: Association of Differential First-Line Treatment with Overall Survival in WHO Grade II and III Gliomas.

INTRODUCTION: Gliomatosis cerebri (GC) is defined by diffuse, widespread glial tumor growth affecting three or more cerebral lobes. Previous studies in gliomas found no distinct histological or molecular GC subtype, yet the presence of GC is associated with worse median overall survival (OS). Here, we explored whether differing therapeutic strategies in first-line treatment could account for this. METHODS: From our University Cancer Center database, 47 patients with histological diagnosis of WHO grade II or III glioma and GC imaging pattern were identified. GC criteria were confirmed by independent review. Patients with WHO grade II or III glioma with non-GC pattern served as control cohort (n = 343). RESULTS: Within the GC patient cohort, lower WHO grade, mutated isocitrate dehydrogenase 1 (IDH1) status, and absence of contrast enhancement were associated with better OS. Compared to the control cohort, patients with GC had significantly shorter OS independent of histological diagnosis or IDH1 mutation status. Patients with GC preferentially received chemotherapy alone (62 vs. 18%), and less frequently radiochemotherapy (21 vs. 27%). OS was significantly shorter in the GC cohort compared to the non-GC cohort both for chemotherapy (3.9 vs. 7.6 years, p = 0.0085) and for combined radiochemotherapy (1.1 vs. 8.4 years, p < 0.0001). However, when only patients who received biopsy plus chemotherapy were analyzed, the differences lost statistical significance (3.5 vs. 6.6 years, p = 0.196). CONCLUSION: We found major differences in the selection of first-line therapies of GC versus non-GC patients. Our results suggest that these differences may partly account for the worse prognosis of GC patients.

Lomustine-temozolomide combination therapy versus standard temozolomide therapy in patients with newly diagnosed glioblastoma with methylated MGMT promoter (CeTeG/NOA-09): a randomised, open-label, phase 3 trial.

BACKGROUND: There is an urgent need for more effective therapies for glioblastoma. Data from a previous unrandomised phase 2 trial suggested that lomustine-temozolomide plus radiotherapy might be superior to temozolomide chemoradiotherapy in newly diagnosed glioblastoma with methylation of the MGMT promoter. In the CeTeG/NOA-09 trial, we aimed to further investigate the effect of lomustine-temozolomide therapy in the setting of a randomised phase 3 trial. METHODS: In this open-label, randomised, phase 3 trial, we enrolled patients from 17 German university hospitals who were aged 18-70 years, with newly diagnosed glioblastoma with methylated MGMT promoter, and a Karnofsky Performance Score of 70% and higher. Patients were randomly assigned (1:1) with a predefined SAS-generated randomisation list to standard temozolomide chemoradiotherapy (75 mg/m2 per day concomitant to radiotherapy [59-60 Gy] followed by six courses of temozolomide 150-200 mg/m2 per day on the first 5 days of the 4-week course) or to up to six courses of lomustine (100 mg/m2 on day 1) plus temozolomide (100-200 mg/m2 per day on days 2-6 of the 6-week course) in addition to radiotherapy (59-60 Gy). Because of the different schedules, patients and physicians were not masked to treatment groups. The primary endpoint was overall survival in the modified intention-to-treat population, comprising all randomly assigned patients who started their allocated chemotherapy. The prespecified test for overall survival differences was a log-rank test stratified for centre and recursive partitioning analysis class. The trial is registered with ClinicalTrials.gov, number NCT01149109. FINDINGS: Between June 17, 2011, and April 8, 2014, 141 patients were randomly assigned to the treatment groups; 129 patients (63 in the temozolomide and 66 in the lomustine-temozolomide group) constituted the modified intention-to-treat population. Median overall survival was improved from 31·4 months (95% CI 27·7-47·1) with temozolomide to 48·1 months (32·6 months-not assessable) with lomustine-temozolomide (hazard ratio [HR] 0·60, 95% CI 0·35-1·03; p=0·0492 for log-rank analysis). A significant overall survival difference between groups was also found in a secondary analysis of the intention-to-treat population (n=141, HR 0·60, 95% CI 0·35-1·03; p=0·0432 for log-rank analysis). Adverse events of grade 3 or higher were observed in 32 (51%) of 63 patients in the temozolomide group and 39 (59%) of 66 patients in the lomustine-temozolomide group. There were no treatment-related deaths. INTERPRETATION: Our results suggest that lomustine-temozolomide chemotherapy might improve survival compared with temozolomide standard therapy in patients with newly diagnosed glioblastoma with methylated MGMT promoter. The findings should be interpreted with caution, owing to the small size of the trial. FUNDING: German Federal Ministry of Education and Research.

Quantitative T1 mapping indicates tumor infiltration beyond the enhancing part of glioblastomas.

The aim of this study was to evaluate whether maps of quantitative T1 (qT1) differences induced by a gadolinium-based contrast agent (CA) are better suited than conventional T1-weighted (T1w) MR images for detecting infiltration inside and beyond the peritumoral edema of glioblastomas. Conventional T1w images and qT1 maps were obtained before and after gadolinium-based CA administration in 33 patients with glioblastoma before therapy. The following data were calculated: (i) absolute qT1-difference maps (qT1 pre-CA - qT1 post-CA), (ii) relative qT1-difference maps, (iii) absolute and (iv) relative differences of conventional T1w images acquired pre- and post-CA. The values of these four datasets were compared in four different regions: (a) the enhancing tumor, (b) the peritumoral edema, (c) a 5 mm zone around the pathology (defined as the sum of regions a and b), and (d) the contralateral normal appearing brain tissue. Additionally, absolute qT1-difference maps (displayed with linear gray scaling) were visually compared with respective conventional difference images. The enhancing tumor was visible both in the difference of conventional pre- and post-CA T1w images and in the absolute qT1-difference maps, whereas only the latter showed elevated values in the peritumoral edema and in some cases even beyond. Mean absolute qT1-difference values were significantly higher (P < 0.01) in the enhancing tumor (838 ± 210 ms), the peritumoral edema (123 ± 74 ms) and in the 5 mm zone around the pathology (81 ± 31 ms) than in normal appearing tissue (32 ± 35 ms). In summary, absolute qT1-difference maps-in contrast to the difference of T1w images-of untreated glioblastomas appear to be able to visualize CA leakage, and thus might indicate tumor cell infiltration in the edema region and beyond. Therefore, the absolute qT1-difference maps are potentially useful for treatment planning.

Health-related quality of life and neurocognitive functioning with lomustine-temozolomide versus temozolomide in patients with newly diagnosed, MGMT-methylated glioblastoma (CeTeG/NOA-09): a randomised, multicentre, open-label, phase 3 trial.

BACKGROUND: The CeTeG/NOA-09 trial showed significantly longer overall survival with combined lomustine-temozolomide therapy compared with standard temozolomide for patients with glioblastoma with methylated MGMT promoter. The trial also aimed to investigate the effect of lomustine-temozolomide therapy on health-related quality of life (HRQOL) and neurocognitive function, which we report here. METHODS: In this randomised, multicentre, open-label, phase 3 trial, newly diagnosed, chemoradiotherapy-naive patients with MGMT-methylated glioblastoma, aged 18-70 years, with a Karnofsky performance score of 70% or higher, were recruited and enrolled at 17 university hospitals in Germany. Patients received standard radiotherapy (60 Gy) and were randomly assigned (1:1, stratified by centre by allocating complete blocks of six to a centre, without masking) to either six 6-week courses of oral combined lomustine (100 mg/m2 on day 1) plus temozolomide (100-200 mg/m2 on days 2-6) or standard oral temozolomide (75 mg/m2 daily during radiotherapy plus six 4-week courses of temozolomide [150-200 mg/m2] on days 1-5, every 4 weeks). The primary endpoint was overall survival. HRQOL, assessed using the European Organisation for Research and Treatment of Cancer (EORTC) quality of life questionnaire core-30 and the EORTC brain cancer module (BN20); and neurocognitive function, assessed using the Mini Mental State Examination (MMSE), plus a neurocognitive test battery (NOA-07), including Trail Making Test A and B (TMT-A and B), working memory tests, and tests for lexical (Controlled Oral Word Association [COWA]) and semantic verbal fluency, were secondary endpoints analysed in the modified intention-to-treat population (mITT; all randomly assigned patients who received at least one dose of study chemotherapy). We used linear mixed-model analyses to investigate differences between treatment groups regarding HRQOL (clinically relevant ≥10 points) and MMSE scores (clinically relevant ≥3 points). The trial is registered with ClinicalTrials.gov, NCT01149109. FINDINGS: Between June 17, 2011 and April 8, 2014, 141 patients were randomly assigned and 129 patients began treatment and were included in the mITT population (63 in the temozolomide and 66 in the lomustine-temozolomide group). Median follow-up for HRQOL (the item global health) was 19·4 months (IQR 7·8-38·6), for MMSE was 15·3 months (4·1-29·6), and for COWA was 11·0 months (0-27·5). We found no significant impairment regarding any item of HRQOL in the lomustine-temozolomide group (difference between the groups for global health 0·30 [95% CI -0·23 to 0·83]; p=0·26). Differences in MMSE were in favour of the temozolomide group (difference -0·11 [95% CI -0·19 to -0·03]; p=0·0058) but were not clinically relevant (1·76/30 points over 4 years). We found no significant difference between the groups in any subtest of the neurocognitive test battery (difference for COWA 0·04 [95% CI -0·01 to 0·09]; p=0·14). INTERPRETATION: The absence of systematic and clinically relevant changes in HRQOL and neurocognitive function combined with the survival benefit of lomustine-temozolomide versus temozolomide alone suggests that a long-term net clinical benefit exists for patients with newly diagnosed glioblastoma with methylation of the MGMT promoter and supports the use of lomustine-temozolomide as a treatment option for these patients. FUNDING: German Federal Ministry of Education and Research.

Fitting algorithms and baseline correction influence the results of non-invasive in vivo quantitation of 2-hydroxyglutarate with 1 H-MRS.

1 H-MRS enables non-invasive detection of 2-hydroxyglutarate (2-HG), an oncometabolite accumulating in gliomas carrying mutations in the isocitrate dehydrogenase (IDH) genes. Reliable 2-HG quantitation requires reproducible post-processing, deployment of fitting algorithms and quantitation methods. We prospectively enrolled 38 patients with suspected or recently diagnosed gliomas (IDH mutated n = 26). The MRI protocol included a 1 H single voxel PRESS sequence with volumes of usually 8 mL or more (20 × 20 × 20 mm3 ) at TE  = 97 ms and 180° pulse spacing. Our aim was to evaluate the reliability of 2-HG quantitation comparing two frequently used software tools and their respective options of baseline correction (jMRUI with the time domain methods AQSES and QUEST, and LCModel, which analyzes the frequency domain data). For AQSES, degrees of freedom for baseline correction constrains were varied. For LCModel, baseline correction was obtained with and without correction of the unknown background term (predefined macromolecules, lipids). Tissue concentrations were calculated based on the phantom replacement method. Quantitation of 2-HG levels showed similar mean 2-HG tissue concentrations for IDH mutated tumors (2.65mM, range 3.06-2.20) for all methods. Bland-Altman plots (difference plots) did not reveal a systematic bias (fixed bias) for any of the algorithms tested, and we were able to show a significant correlation regarding 2-HG concentration at the same echo time with few statistical outliers (parametric correlation). However, evaluation of outliers suggested that in vivo quantitation of 2-HG is affected not only by the fitting domain (time or frequency), but also by the baseline correction, which is a major contributing factor to the result of 2-HG fitting. Clinical application of 2-HG quantitation as a prognostic or predictive biomarker, particularly in multicenter trials, requires standardized use of fitting methods and baseline correction procedures.

Baseline T1 hyperintense and diffusion-restricted lesions are not linked to prolonged survival in bevacizumab-treated glioblastoma patients of the GLARIUS trial.

PURPOSE: The phase II GLARIUS trial assigned patients with newly diagnosed, O-6-methylguanine-DNA methyltransferase promoter non-methylated glioblastoma to experimental bevacizumab/irinotecan (BEV/IRI) or standard temozolomide (TMZ). To identify subpopulations with a particularly favorable course, we assessed the prognostic potential of magnetic resonance imaging (MRI) markers before treatment onset. METHODS: MRIs at baseline (before treatment onset) were analyzed for T1-hyperintense and diffusion-restricted lesions; as well as the presence of both hyperintense and diffusion-restricted (double positive) lesions. The MRI findings were correlated with overall and progression-free survival. RESULTS: MRI scans were evaluable in 71% of the GLARIUS modified intention-to-treat population (n = 121 of 170; 88 patients in the BEV/IRI arm, and 33 patients in the TMZ control arm). Diffusion-restricted and T1 hyperintense lesions were present in 60% and 65% of patients in BEV/IRI arm, while 57% and 63% were found in the TMZ arm, respectively. Double positive lesions were found in 37% of BEV/IRI patients and in 39% of TMZ patients. Neither the presence of T1-hyperintense, diffusion-restricted lesions, nor double positive lesions were associated with improved survival. CONCLUSIONS: Baseline T1-hyperintense and diffusion-restricted lesions are not suitable to predict progression-free or overall survival of patients treated with bevacizumab/irinotecan or temozolomide.

Intracellular pH measured by 31 P-MR-spectroscopy might predict site of progression in recurrent glioblastoma under antiangiogenic therapy.

PURPOSE: In solid tumors, changes in the expression/activity of plasma membrane ion transporters facilitate proton efflux and enable tumor cells to maintain a higher intracellular pH (pHi ), while the microenvironment (pHe ) is commonly more acidic. This supports various tumor-promoting mechanisms. We propose that these changes in pH take place before a magnetic resonance imaging (MRI)-detectable brain tumor recurrence occurs. MATERIALS AND METHODS: We enrolled 66 patients with recurrent glioblastoma, treated with bevacizumab. Patients received a baseline and 8-week follow-up MRI including 1 H/31 P MRSI (spectroscopy) on a 3T clinical scanner, until progressive disease according to Response Assessment in Neuro-Oncology (RANO) criteria occurred. Fourteen patients showed a distant or diffuse tumor recurrence (subsequent tumor) during treatment and were therefore selected for further evaluation. At the site of the subsequent tumor, an area of interest for MRSI voxel selection was retrospectively defined on radiographically unaffected baseline MRI sequences. RESULTS: Before treatment, pHi in the area of interest (subsequent tumor) was significantly higher than pHi of the contralateral normal-appearing tissue (control; P < 0.001). It decreased at the time of best response (P = 0.06), followed by a significant increase at progression (P = 0.03; baseline mean: 7.06, median: 7.068, SD: 0.032; best response mean: 7.044, median: 7.036, SD: 0.025; progression mean: 7.08, median: 7.095, SD 0.035). Until progression, the subsequent tumor was not detectable on standard MRI sequences. The area of existing tumor responded similar, but changes were not significant (decrease P = 0.22; increase P = 0.28). CONCLUSION: Elevated pHi in radiographically unaffected tissue at baseline might precede MRI-detectable progression in patients with recurrent glioblastoma treated with bevacizumab. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1200-1208.

Bevacizumab for Patients with Recurrent Multifocal Glioblastomas.

In patients with glioblastoma, antiangiogenic therapy with bevacizumab (BEV) has been shown to improve progression-free survival (PFS), but not overall survival (OS). Especially in patients with an unusual infiltrative phenotype as seen in multifocal glioblastoma, the use of BEV therapy is still more controversial. Therefore, we prepared a retrospective case series with 16 patients suffering from a multifocal glioblastoma treated with BEV. We compared these patients to a matched control cohort of 16 patients suffering from glioblastoma with a single lesion treated with BEV. The objective of this study was to evaluate whether the course of disease differs in glioblastoma patients with a multifocal disease pattern compared to those with a single lesion only. Patients were treated with BEV monotherapy or BEV in combination with irinotecan or lomustine (CCNU). Response rates and PFS were similar in both groups. There was a trend for an unfavorable OS in the patient group with multifocal glioblastoma, which was expected due to the generally worse prognosis of multifocal glioblastoma. We investigated whether BEV therapy affects the invasive growth pattern as measured by the appearance of new lesions on magnetic resonance imaging (MRI). Under BEV therapy, there was a trend for a lower frequency of new lesions both in multifocal and solitary glioblastoma. Based on these results, BEV therapy at relapse appears to be justified to no lesser extent in multifocal glioblastoma than in solitary glioblastoma.

Bevacizumab for Patients with Recurrent Gliomas Presenting with a Gliomatosis Cerebri Growth Pattern.

Bevacizumab has been shown to improve progression-free survival and neurologic function, but failed to improve overall survival in newly diagnosed glioblastoma and at first recurrence. Nonetheless, bevacizumab is widely used in patients with recurrent glioma. However, its use in patients with gliomas showing a gliomatosis cerebri growth pattern is contentious. Due to the marked diffuse and infiltrative growth with less angiogenic tumor growth, it may appear questionable whether bevacizumab can have a therapeutic effect in those patients. However, the development of nodular, necrotic, and/or contrast-enhancing lesions in patients with a gliomatosis cerebri growth pattern is not uncommon and may indicate focal neo-angiogenesis. Therefore, control of growth of these lesions as well as control of edema and reduction of steroid use may be regarded as rationales for the use of bevacizumab in these patients. In this retrospective patient series, we report on 17 patients with primary brain tumors displaying a gliomatosis cerebri growth pattern (including seven glioblastomas, two anaplastic astrocytomas, one anaplastic oligodendroglioma, and seven diffuse astrocytomas). Patients have been treated with bevacizumab alone or in combination with lomustine or irinotecan. Seventeen matched patients treated with bevacizumab for gliomas with a classical growth pattern served as a control cohort. Response rate, progression-free survival, and overall survival were similar in both groups. Based on these results, anti-angiogenic therapy with bevacizumab should also be considered in patients suffering from gliomas with a mainly infiltrative phenotype.

Gliomatosis cerebri: no evidence for a separate brain tumor entity.

Gliomatosis cerebri (GC) is presently considered a distinct astrocytic glioma entity according to the WHO classification for CNS tumors. It is characterized by widespread, typically bilateral infiltration of the brain involving three or more lobes. Genetic studies of GC have to date been restricted to the analysis of individual glioma-associated genes, which revealed mutations in the isocitrate dehydrogenase 1 (IDH1) and tumor protein p53 (TP53) genes in subsets of patients. Here, we report on a genome-wide analysis of DNA methylation and copy number aberrations in 25 GC patients. Results were compared with those obtained for 105 patients with various types of conventional, i.e., non-GC gliomas including diffuse astrocytic gliomas, oligodendrogliomas and glioblastomas. In addition, we assessed the prognostic role of methylation profiles and recurrent DNA copy number aberrations in GC patients. Our data reveal that the methylation profiles in 23 of the 25 GC tumors corresponded to either IDH mutant astrocytoma (n = 6), IDH mutant and 1p/19q codeleted oligodendroglioma (n = 5), or IDH wild-type glioblastoma including various molecular subgroups, i.e., H3F3A-G34 mutant (n = 1), receptor tyrosine kinase 1 (RTK1, n = 4), receptor tyrosine kinase 2 (classic) (RTK2, n = 2) or mesenchymal (n = 5) glioblastoma groups. Two tumors showed methylation profiles of normal brain tissue due to low tumor cell content. While histological grading (WHO grade IV vs. WHO grade II and III) was not prognostic, the molecular classification as classic/RTK2 or mesenchymal glioblastoma was associated with worse overall survival. Multivariate Cox regression analysis revealed MGMT promoter methylation as a positive prognostic factor. Taken together, DNA-based large-scale molecular profiling indicates that GC comprises a genetically and epigenetically heterogeneous group of diffuse gliomas that carry DNA methylation and copy number profiles closely matching the common molecularly defined glioma entities. These data support the removal of GC as a distinct glioma entity in the upcoming revision of the WHO classification.

Erratum to: Gliomatosis cerebri: no evidence for a separate brain tumor entity.

Erratum to: Acta Neuropathol DOI 10.1007/s00401­015­1495­z. The original version of this article contained errors in the alignment of several entries in Tables 4 and 5. The corrected Tables 4 and 5 are given below. The original article has been updated accordingly.

Costs and cost-driving factors for acute treatment of adults with status epilepticus: A multicenter cohort study from Germany.

OBJECTIVE: To provide first data on inpatient costs and cost-driving factors due to nonrefractory status epilepticus (NSE), refractory status epilepticus (RSE), and super-refractory status epilepticus (SRSE). METHODS: In 2013 and 2014, all adult patients treated due to status epilepticus (SE) at the university hospitals in Frankfurt, Greifswald, and Marburg were analyzed for healthcare utilization. RESULTS: We evaluated 341 admissions in 316 patients (65.7 ± [standard deviation]18.2 years; 135 male) treated for SE. Mean costs of hospital treatment were €14,946 (median €5,278, range €776-€152,911, €787 per treatment day) per patient per admission, with a mean length of stay (LOS) of 19.0 days (median 14.0, range 1-118). Course of SE had a significant impact on mean costs, with €8,314 in NSE (n = 137, median €4,597, €687 per treatment day, 22.3% of total inpatient costs due to SE), €13,399 in RSE (n = 171, median €7,203, €638/day, 45.0% of total costs, p < 0.001), and €50,488 in SRSE (n = 33, median €46,223, €1,365/day, 32.7% of total costs, p < 0.001). Independent cost-driving factors were SRSE, ventilation, and LOS of >14 days. Overall mortality at discharge was 14.4% and significantly higher in RSE/SRSE (20.1%) than in NSE (5.8%). SIGNIFICANCE: Acute treatment of SE, and particularly SRSE and ventilation, are associated with high hospital costs and prolonged LOS. Extrapolation to the whole of Germany indicates that SE causes hospital costs of >€200 million per year. Along with the demographic change, incidence of SE will increase and costs for hospital treatment and sequelae of SE will rise.

Prognostic factors in recurrent glioblastoma patients treated with bevacizumab.

The value of bevacizumab (BEV) in recurrent glioblastoma is unclear. Imaging parameters and progression-free survival (PFS) are problematic endpoints. Few data exist on clinical factors influencing overall survival (OS) in unselected patients with recurrent glioblastoma exposed to BEV. We retrospectively analyzed 174 patients with recurrent glioblastoma treated with BEV at two German brain tumor centers. We evaluated general patient characteristics, MGMT status, pretreatment, concomitant oncologic treatment and overall survival. Karnofsky performance score, number of prior chemotherapies, number of prior recurrences and combined treatment with irinotecan (IRI) were significantly associated with OS in univariate analysis. We did not find differences in OS related to sex, age, histology, MGMT status, prior surgical treatment or number of prior radiotherapies. Combined treatment with IRI and higher KPS both remained significantly associated with prolonged survival in multivariate analysis, but patients receiving IRI co-treatment had less advanced disease. Grouping into clinically relevant categories revealed an OS of 16.9 months from start of BEV in patients with first recurrence and KPS ≥ 80 % (n = 25). In contrast, in patients with second recurrence and KPS < 80 %, OS was 3.6 months (n = 27). Our observational data support an early use of BEV in patients with good performance status. The benefit of co-treatment with IRI in our cohort seems to be the result of biased patient recruitment.

Improved visibility of brain tumors in synthetic MP-RAGE anatomies with pure T1 weighting.

Conventional MRI for brain tumor diagnosis employs T2 -weighted and contrast-enhanced T1 -weighted sequences. Non-enhanced T1 -weighted images provide improved anatomical details for precise tumor location, but reduced tumor-to-background contrast as elevated T1 and proton density (PD) values in tumor tissue affect the signal inversely. Radiofrequency (RF) coil inhomogeneities may further mask tumor and edema outlines. To overcome this problem, the aims of this work were to employ quantitative MRI techniques to create purely T1 -weighted synthetic anatomies which can be expected to yield improved tissue and tumor-to-background contrasts, to compare the quality of conventional and synthetic anatomies, and to investigate optical contrast and visibility of brain tumors and edema in synthetic anatomies. Conventional magnetization-prepared rapid acquisition of gradient echoes (MP-RAGE) anatomies and maps of T1 , PD and RF coil profiles were acquired in comparable and clinically feasible times. Three synthetic MP-RAGE anatomies (PD T1 weighting both with and without RF bias; pure T1 weighting) were calculated for healthy subjects and 32 patients with brain tumors. In healthy subjects, the PD T1 -weighted synthetic anatomies with RF bias precisely matched the conventional anatomies, yielding high signal-to-noise (SNR) and contrast-to-noise (CNR) ratios. Pure T1 weighting yielded lower SNR, but high CNR, because of increased optical contrasts. In patients with brain tumors, synthetic anatomies with pure T1 weighting yielded significant increases in optical contrast and improved visibility of tumor and edema in comparison with anatomies reflecting conventional T1 contrasts. In summary, the optimized purely T1 -weighted synthetic anatomy with an isotropic resolution of 1 mm, as proposed in this work, considerably enhances optical contrast and visibility of brain tumors and edema.

Bevacizumab treatment induces metabolic adaptation toward anaerobic metabolism in glioblastomas.

Anti-angiogenic therapy in glioblastoma (GBM) has unfortunately not led to the anticipated improvement in patient prognosis. We here describe how human GBM adapts to bevacizumab treatment at the metabolic level. By performing (13)C6-glucose metabolic flux analysis, we show for the first time that the tumors undergo metabolic re-programming toward anaerobic metabolism, thereby uncoupling glycolysis from oxidative phosphorylation. Following treatment, an increased influx of (13)C6-glucose was observed into the tumors, concomitant to increased lactate levels and a reduction of metabolites associated with the tricarboxylic acid cycle. This was confirmed by increased expression of glycolytic enzymes including pyruvate dehydrogenase kinase in the treated tumors. Interestingly, L-glutamine levels were also reduced. These results were further confirmed by the assessment of in vivo metabolic data obtained by magnetic resonance spectroscopy and positron emission tomography. Moreover, bevacizumab led to a depletion in glutathione levels indicating that the treatment caused oxidative stress in the tumors. Confirming the metabolic flux results, immunohistochemical analysis showed an up-regulation of lactate dehydrogenase in the bevacizumab-treated tumor core as well as in single tumor cells infiltrating the brain, which may explain the increased invasion observed after bevacizumab treatment. These observations were further validated in a panel of eight human GBM patients in which paired biopsy samples were obtained before and after bevacizumab treatment. Importantly, we show that the GBM adaptation to bevacizumab therapy is not mediated by clonal selection mechanisms, but represents an adaptive response to therapy.

Comprehensive diagnostics in a case of hereditary diffuse leukodystrophy with spheroids.

BACKGROUND: Hereditary diffuse leukodystrophy with spheroids is a rare type of leukoencephalopathy. Mutations in the colony stimulating factor 1 receptor have recently been identified to be the cause of this microgliopathy. Clinical and radiological presentation can often misguide physicians during the diagnosis of patients with this underdiagnosed disease. CASE PRESENTATION: We present a 29 year-old woman with a rapid course of hereditary diffuse leukodystrophy with spheroids. She mainly showed cognitive impairment and severe motor dysfunctions. Her MRI showed spotted and confluent hyperintensities of the white matter on T2-weighted images involving the corticospinal tract as well as the corpus callosum. Further, those lesions showed striking restricted diffusion. As this restricted diffusion in all areas showing signs of leukoencephalopathy was so impressive we searched Medline for these terms and got hereditary diffuse leukodystrophy with spheroids as one of the first results. After a comprehensive diagnostic workup and exclusion of other leukoencephalopathies, stereotactic biopsy and genetic testing confirmed the diagnosis. CONCLUSION: This case points out at two important features of hereditary diffuse leukodystrophy with spheroids being spotted and/or confluent leukoencephalopathy with areas of restricted diffusion. This might help to identify more patients with this underdiagnosed disease. Moreover, the rapid clinical course in our patient raises the question whether the relatively pronounced areas of restricted diffusion are indicative of a more acute progression of the disease.

Quantitative T1 and T2 mapping in recurrent glioblastomas under bevacizumab: earlier detection of tumor progression compared to conventional MRI.

INTRODUCTION: Treatment with the humanized anti-vascular endothelial growth factor (VEGF) antibody bevacizumab in glioblastoma patients suppresses contrast enhancement via the reduction of vascular permeability, which does not necessarily indicate real reduction of tumor cell mass. Therefore, other imaging criteria are needed to recognize tumor growth under bevacizumab more reliably. It is still unknown, whether quantitative T1 mapping is useful to monitor the effects of anti-angiogenic therapy or to indicate a tumor progression earlier and more reliable compared to conventional magnetic resonance imaging (MRI) sequences. This raised the question whether quantitative T1 mapping is more suitable to monitor treatment effects of bevacizumab. METHODS: Conventional and quantitative MRI was performed on six consecutive patients with recurrent glioblastoma before treatment with bevacizumab and every 8 weeks thereafter until further tumor progression. Quantitative T1 maps before and after intravenous application of contrast agent and quantitative T2 maps were performed to calculate serial differential maps and subtraction maps from one time point, subtracting contrast-enhanced T1 maps from non-contrast T1 maps. RESULTS: In five illustrative cases, tumor progression was documented earlier in differential T1 relaxation time (DiffT1) and T2 relaxation time (DiffT2) maps before changes in the conventional MRI studies were obvious. Four patients showed previous prolongation of T1 relaxation time in the DiffT1 maps, suggesting tumor progression, and subtraction maps revealed faint contrast enhancement matching with the areas of T1 prolongation. CONCLUSION: Our results emphasize that quantitative relaxation time mapping could be a promising method for tumor monitoring in glioblastoma patients under anti-angiogenic therapy. Quantitative T1 mapping seems to detect enhancing tumor earlier than conventional contrast-enhanced T1-weighted images.

Confounding factors in diagnostics of MGMT promoter methylation status in glioblastomas in stereotactic biopsies.

BACKGROUND: In nonresectable glioblastoma (GBM), stereotactic biopsies are performed to retrieve tissue for diagnostic purposes. The analysis of O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation adds prognostic and predictive information. OBJECTIVES: The aim of the study was to detect confounding factors that limit the number of conclusive MGMT promoter methylation results. METHODS: We analyzed 71 consecutive GBM patients undergoing stereotactic biopsy on whom MGMT analysis was performed by methylation-specific polymerase chain reaction. Specimens were correlated to imaging by coregistration and prospective documentation of biopsy localization. Our findings were validated in an additional 62 GBM stereotactic biopsies. RESULTS: Our results demonstrate that the best MGMT promoter methylation results were obtained from samples (n = 71) taken in a tangential manner from tumor areas showing contrast enhancement in magnetic resonance imaging. In the additional validation series of 62 stereotactically biopsied GBM, we were able to increase the rate of conclusive MGMT promoter methylation results from 76.1 to 85.48% by strictly planning the route of biopsy in a tangential manner if possible. CONCLUSIONS: These results underline that within the contrast-enhanced tumor part, choosing the trajectory in a tangential manner increases the diagnostic yield for conclusive MGMT promoter methylation analyses in stereotactic biopsies as a basis for patient stratification and individualized therapy.

MR perfusion in and around the contrast-enhancement of primary CNS lymphomas.

Diffuse cerebral infiltration of primary brain tumors may be missed on conventional MRI. In glioblastomas it may be visible on MR-perfusion images as an elevated rCBV adjacent to the contrast enhancing area (penumbra). We aimed to evaluate whether penumbral rCBV of primary central nervous system lymphomas (PCNSL) is also increased and if PCNSL perfusion has different features than that of glioblastomas. We measured dynamic susceptibility contrast MR-perfusion at 3 Tesla in 38 presurgical patients with histopathological diagnosis of PCNSL (n = 19) and glioblastoma (n = 19). We compared normalized rCBV within and adjacent to the enhancing area and evaluated time-signal intensity curves (TSIC) in all patients. Histopathological comparison of patients with different TSIC patterns (with or without shoulder-like increase) was performed. Relative to the normal tissue, rCBV within and adjacent to the enhancing area was increased (p < 0.05) in both glioblastomas and PCNSL. In the penumbra the increase was moderate in both groups, with 1.4 ± 0.46 in PCNSL and 1.82 ± 0.82 in glioblastomas (p = 0.07 between groups). In the enhancing tumor the increase was moderate in PCNSL (1.46 ± 0.62) and marked in glioblastomas (4.13 ± 2.44) (p < 0.001 between groups). A shoulder-like TSIC increase was exclusively found in PCNSL (11/19) and was significantly associated with a less prominent reticulin fibre network compared to the PCNSL without a shoulder-like TSIC increase. The moderately increased penumbral rCBV in PCNSL and glioblastomas reveals tumor-related changes beyond the tumor borders which are invisible with conventional MRI. PCNSL can be differentiated from glioblastomas through their significantly lower rCBV and shoulder-like signal intensity changes inside the enhancing area.