MGMT Methylation Status Research Articles

A large, multicenter, retrospective study to identify a cutoff of MGMT methylation status by quantitative pyrosequencing approach in patients (PTS) with glioblastoma (GBM).

2012A LARGE, MULTICENTER, RETROSPECTIVE STUDY TO IDENTIFY A CUT-OFF OF MGMT METHYLATION STATUS BY QUANTITATIVE PYROSEQUENCING APPROACH IN PATIENTS (PTS) WITH GLIOBLASTOMA (GBM). Background: MGMT pr...

Concordant association validates MGMT methylation and protein expression as favorable prognostic factors in glioma patients on alkylating chemotherapy (Temozolomide)

O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation and its subsequent loss of protein expression has been identified to have a variable impact on clinical outcome of glioma patients indicated for chemotherapy with alkylating agents (Temozolomide). This study investigated methylation status of MGMT gene along with in situ protein expression in malignant glioma patients of different histological types to evaluate the associated clinical outcome vis-a-vis use of alkylating drugs and radiotherapy. Sixty three cases of glioma were evaluated for MGMT promoter methylation by methylation-specific PCR (MS-PCR) and protein expression by immunostaining (IHC). Methylation status of MGMT and loss of protein expression showed a very high concordant association with better survival and progression free survival (PFS) (p < 0.0001). Multivariate Cox regression analysis showed both MGMT methylation and loss of protein as significant independent prognostic factors in glioma patients with respect to lower Hazard Ratio (HR) for better OS and PFS) [p < 0.05]. Interestingly concordant MGMT methylation and lack of protein showed better response in TMZ therapy treated patient subgroups with HR of 2.02 and 0.76 (p < 0.05). We found the merits of prognostication of MGMT parameters, methylation as well as loss of its protein as predictive factors for favorable outcome in terms of better survival for TMZ therapy.

Overview on current treatment standards in high-grade gliomas.

High-grade gliomas (HGGs) are the most common primary tumors of the central nervous system, which include anaplastic gliomas (grade III) and glioblastomas (GBM, grade IV). Surgery is the mainstay of treatment in HGGs in order to achieve a histological and molecular characterization, as well as relieve neurological symptoms and improve seizure control. Combinations of some molecular factors, such as IDH 1-2 mutations, 1p/19q codeletion and MGMT methylation status, allow to classify different subtypes of gliomas and identify patients with different outcome. The SOC in HGGs consists in a combination of radiotherapy and chemotherapy with alkylating agents. Despite this therapeutic approach, tumor recurrence occurs in HGGs, and new surgical debulking, reirradiation or second-line chemotherapy are needed. Considering the poor results in terms of survival, several clinical trials have explored the efficacy and tolerability of antiangiogenic agents, targeted therapies against epidermal growth factor receptor (EGFR) and different immunotherapeutic approaches in recurrent and newly-diagnosed GBM, including immune checkpoint inhibitors (ICIs), and cell- or peptide-based vaccination with unsatisfactory results in term of disease control. In this review we describe the major updates in molecular biology of HGGs according to 2016 WHO Classification, the current management in newly-diagnosed and recurrent GBM and grade III gliomas, and the results of the most relevant clinical trials on targeted agents and immunotherapy.

Comparison of 1p and 19q status of glioblastoma by whole exome sequencing, array-comparative genomic hybridization, and fluorescence in situ hybridization.

According to the 2016 World Health Organization classification of tumors of the central nervous system, detecting 1p/19q co-deletion became essential in clinical neuropathology for gliomas with oligodendroglioma-like morphology. Here, we assessed genomic profiles of glioblastoma in 80 cases including 1p/19q status using fluorescent in situ hybridization (FISH), array-comparative genomic hybridization (aCGH), and/or whole exome sequencing (WES). Paraffin-embedded tumor tissues were subjected to FISH analysis, and the corresponding frozen tissues from the same tumors were evaluated for aCGH and/or WES for 1p/19q co-deletion and other genetic parameters, which included IDH1-R132H, ATRX, TP53, CIC, and NOTCH1 mutations and MGMT methylation status. We also evaluated correlations between 1p/19q co-deletion status and molecular markers or clinical outcomes. The FISH analyses revealed 1p/19q co-deletion in two cases, isolated deletion of 1p in six cases, and 19q in two cases, whereas the aCGH and WES results showed isolated deletion of 19q in four cases and 19 monosomy in only one case. Eleven cases showed discordant 1p/19q results between aCGH/WES and FISH analysis, and in most of them, 1p and/or 19q deletion on FISH analysis corresponded to the partial deletions at 1p36 and/or 19q13 on aCGH/WES. Our cohort exhibited IDH1-R132H mutations (5.4%), MGMT promotor methylation (34.6%), and mutations in ATRX (9.5%), TP53 (33.3%), and NOTCH1 (3.8%) but not in CIC (0%). In addition, MGMT methylation and ATRX mutation were significantly associated with clinical prognosis. In glioblastomas, partial deletions of 1p36 and/or 19q13 were uncommon, some of which appeared as 1p and/or 19q deletions on FISH analysis.

DNA methylation is related to the occurrence of breast cancer and is not affected by culture conditions.

The present study aimed to explore the relationship between DNA methylation and breast cancer under different cell culture conditions. MCF‑7 breast cancer cells were cultured in two‑dimensional (2D), three‑dimensional (3D) and orthotopic transplantation (Ti) adhesion substrates. Principal component analysis (PCA) was used for global visualization of these three samples. The methylation status of CpG sites was examined by unsupervised clustering analysis. Scatter plots and histograms were constructed from the mean β‑values from 3Dvs.2D, 3Dvs.Ti and Tivs.2D analysis. In addition, analyses of Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were conducted to explore the putative biological functions in which mutL homolog (MLH), phosphatase and tensin homolog (PTEN), runt‑related transcription factor (RUNX), Ras association domain family (RASSF), cadherin 1 (CDH1), O‑6‑methylguanine‑DNA methyltransferase (MGMT) and P16 may serve a role. Quantitative methylation‑specific polymerase chain reaction (QMSP) was performed to determine the influence of culturing conditions on important gene expression. Results from PCA analysis indicated that the three samples were closely connected with each other. Venn diagrams revealed that certain differential methylation positions were common among the three sample groups, and 116 CpG positions were identified that appeared to be hypermethylated. The methylation patterns were more similar between 3D vs. 2D cultures compared with those between 3Dvs.Ti or between Ti vs. 2D. Results of GO term and KEGG pathway analyses indicated that genes were enriched in four pathways, including transporter activity and G‑protein coupled receptor activity. In addition, QMSP analysis identified no notable differences in the methylation status of MLH, PTEN, RUNX, RASSF, CDH1, MGMT and P16 under 2D, 3D and Ti culture conditions. In conclusion, abnormal DNA methylation is related with breast cancer, and the methylation status did not change in breast cancer cells cultured in different conditions.

MGMT pyrosequencing-based cut-off methylation level and clinical outcome in patients with glioblastoma multiforme.

MGMT promoter methylation has been associated with improved survival in glioblastoma multiforme treated with temozolomide. However, there is no consensus on specific cut-off levels of methylation. The aims of the study were to explore the prognostic impact of MGMT methylation status and to analyze the role of specific cut-off values. We analyzed 108 glioblastoma multiforme patients treated between 2008 and 2013 stratified according to three pyrosequencing-based quantitative methylation in: unmethylated (methylation <9%), intermediate (9-29%) and highly methylated (>29%). The three-class stratification has a prognostic impact (median progression-free survival: 7.97, 11.6 and 15months respectively; p=0.004; median OS: 13.2, 15.8 and 19.5months, respectively; p=0.0002), especially in patients exposed to temozolomide. Our study confirmed that the independent prognostic role of MGMT methylation status. An average level of methylation between all investigated CpGs of 9% may help discriminating between methylated and unmethylated tumors.

A novel prognostic six-CpG signature in glioblastomas.

We aimed to identify a clinically useful biomarker using DNA methylation-based information to optimize individual treatment of patients with glioblastoma (GBM). A six-CpG panel was identified by incorporating genome-wide DNA methylation data and clinical information of three distinct discovery sets and was combined using a risk-score model. Different validation sets of GBMs and lower-grade gliomas and different statistical methods were implemented for prognostic evaluation. An integrative analysis of multidimensional TCGA data was performed to molecularly characterize different risk tumors. The six-CpG risk-score signature robustly predicted overall survival (OS) in all discovery and validation cohorts and in a treatment-independent manner. It also predicted progression-free survival (PFS) in available patients. The multimarker epigenetic signature was demonstrated as an independent prognosticator and had better performance than known molecular indicators such as glioma-CpG island methylator phenotype (G-CIMP) and proneural subtype. The defined risk subgroups were molecularly distinct; high-risk tumors were biologically more aggressive with concordant activation of proangiogenic signaling at multimolecular levels. Accordingly, we observed better OS benefits of bevacizumab-contained therapy to high-risk patients in independent sets, supporting its implication in guiding usage of antiangiogenic therapy. Finally, the six-CpG signature refined the risk classification based on G-CIMP and MGMT methylation status. The novel six-CpG signature is a robust and independent prognostic indicator for GBMs and is of promising value to improve personalized management.

The Prognostic Roles of Gender and O6-Methylguanine-DNA Methyltransferase Methylation Status in Glioblastoma Patients: The Female Power.

Clinical and molecular factors are essential to define the prognosis in patients with glioblastoma (GBM). O6-methylguanine-DNA methyltransferase (MGMT) methylation status, age, Karnofsky Performance Status (KPS), and extent of surgical resection are the most relevant prognostic factors. Our investigation of the role of gender in predicting prognosis shows a slight survival advantage for female patients. We performed a prospective evaluation of the Project of Emilia Romagna on Neuro-Oncology (PERNO) registry to identify prognostic factors in patients with GBM who received standard treatment. A total of 169 patients (99 males [58.6%] and 70 females [41.4%]) were evaluated prospectively. MGMT methylation was evaluable in 140 patients. Among the male patients, 36 were MGMT methylated (25.7%) and 47 were unmethylated (33.6%); among the female patients, 32 were methylated (22.9%) and 25 were unmethylated (17.9%). Survival was longer in the methylated females compared with the methylated males (P= 0.028) but was not significantly different between the unmethylated females and the unmethylated males (P= 0.395). In multivariate analysis, gender and MGMT methylation status considered together (methylated females vs. methylated males; hazard ratio [HR], 0.459; 95% confidence interval [CI], 0.242-0.827; P= 0.017), age (HR, 1.025; 95% CI, 1.002-1.049; P= 0.032), and KPS (HR, 0.965; 95% CI, 0.948-0.982; P< 0.001) were significantly correlated with survival. Survival was consistently longer among MGMT methylated females compared with males. Gender can be considered as a further prognostic factor.

O-6-methylguanine-DNA methyltransferase promoter methylation can change in glioblastoma recurrence due to intratumor heterogeneity

Background and Aim: The standard-of-care for patients with glioblastoma (GBM) is surgery followed by concurrent chemotherapy with temozolomide and radiotherapy. O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is commonly assessed in GBM as a predictive marker of response to temozolomide. Although MGMT methylation status has been shown to change between primary and recurrent GBM, no indication exists on retesting MGMT in recurrent GBM. In addition, what causes the change in MGMT methylation has yet to be identified. In this study, we aimed to investigate whether MGMT promoter methylation in recurrent GBM was influenced by intratumor heterogeneity in the initial GBM tumor. Materials and Methods: We investigated the status of MGMT promoter methylation in different samples taken from concentric layers of 24 GBMs and in 11-paired surgically resected recurrences. The neoplastic nature of samples submitted for methylation analysis was preliminary verified through histological examination; the fragments were accurately chosen to have adequate cellularity and minimal amount of nontumor contaminants. Results: About 27% (3 out of 11) of the recurrences had changed MGMT methylation status compared to the initial tumor. Initial tumor heterogeneity might play a role in this change, as all three cases had intratumor heterogeneity (with the central part of the tumor methylated and the peripheral part unmethylated) in the primary GBM. Conclusion: This study suggests that MGMT methylation variation in recurrent GBM may depend on intratumor heterogeneity in the initial tumor. Intratumor heterogeneity and possible changes in the recurrence should be taken into account when testing MGMT promoter methylation status as a predictive factor orienting therapeutic decisions in patients with GBM.

MGMT gene promoter methylation and its correlation with clinicopathological parameters in glioblastomas.

MGMT (O6-methyl guanine DNA methyl transferase) promoter hypermethylation is a prognostic and predictive biomarker for glioblastomas (GBM). To evaluate the frequency of MGMT methylation status in a single institute series of 134 GBMs and correlate it with clinical (age, sex, location, survival) and other molecular parameters [such as p53 expression, alpha thalassemia/mental retardation syndrome X-linked (ATRX) expression, isocitrate dehydrogenase (IDH) 1R132H mutation, and epidermal growth factor receptor (EGFR) gene amplification]. One hundred and thirty-four GBMs were evaluated by methylation-specific polymerase chain reaction (MSP) for MGMT promoter methylation status. The results were correlated with the above mentioned clinicopathological parameters. MGMT gene promoter methylation was identified in 49.2% (66/134) GBMs, and was significantly associated with IDH1R132H mutation (14/66; 21%; P - value, 0.01) and ATRX loss (15/66; 23%; P - value, 0.01). Confluent necrosis was found to be significantly associated with MGMT unmethylation status (P - value: 0.002). Multivariable logistic regression analysis showed confluent necrosis as a single independent predictor (odds ratio [OR], 2.5; confidence interval [CI], 1.0-5.8; P - value, 0.04) of MGMT unmethylation status among all the parameters studied. The frequency of MGMT promoter methylation in GBMs was 49.2%, which was significantly associated with IDHR132H mutation and ATRX loss. In addition, the presence of confluent necrosis was significantly associated with MGMT unmethylation and was found to be an independent predictor of the same.

Temporal stability of MGMT promoter methylation in glioblastoma patients undergoing STUPP protocol.

Epigenetic silencing of O-6-methylguanine-DNA methyltransferase (MGMT) promoter via methylation in a glioblastoma (GBM), has been correlated with a more favourable response to alkylating chemotherapeutic agents such as temozolomide. The use of global methylation surrogates such as Long Interspersed Nucleotide Element 1 (LINE1) may also be valuable in order to fully understand these highly heterogeneous tumours. In this study, we analysed both original and recurrent GBMs in 22 patients (i.e. 44 tumours), for both MGMT and LINE1 methylation status. In the 22 patients: 14 (63.6%) displayed MGMT methylation stability in the recurrent GBM versus 8 (36.4%), with instability of methylation status. No significant differences in overall and progression free survival was evident between these two groups. LINE1 methylation status remained stable for 12 (54.5%) of recurrent GBM patients versus 9 (41%) of the patients with instability in LINE1 methylation status (p = 0.02), resulting in an increase in overall survival of the stable LINE1 group (p = 0.04). The results obtained demonstrated major epigenetic instability of GBMs treated with temozolomide as part of the STUPP protocol. GBMs appear to undergo selective evolution post-treatment, and have the ability to recur with a newly reprogrammed epigenetic status. Selective targeting of the altered epigenomes in recurrent GBMs may facilitate the future development of both prognostic biomarkers and enhanced therapeutic strategies.

Discriminating MGMT promoter methylation status in patients with glioblastoma employing amide proton transfer-weighted MRI metrics.

To explore the feasibility of using amide proton transfer-weighted (APTw) MRI metrics as surrogate biomarkers to identify the O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status in glioblastoma (GBM). Eighteen newly diagnosed GBM patients, who were previously scanned at 3T and had a confirmed MGMT methylation status, were retrospectively analysed. For each case, a histogram analysis in the tumour mass was performed to evaluate several quantitative APTw MRI metrics. The Mann-Whitney test was used to evaluate the difference in APTw parameters between MGMT methylated and unmethylated GBMs, and the receiver-operator-characteristic analysis was further used to assess diagnostic performance. Ten GBMs were found to harbour a methylated MGMT promoter, and eight GBMs were unmethylated. The mean, variance, 50th percentile, 90th percentile and Width10-90 APTw values were significantly higher in the MGMT unmethylated GBMs than in the MGMT methylated GBMs, with areas under the receiver-operator-characteristic curves of 0.825, 0.837, 0.850, 0856 and 0.763, respectively, for the discrimination of MGMT promoter methylation status. APTw signal metrics have the potential to serve as valuable imaging biomarkers for identifying MGMT methylation status in the GBM population. • APTw-MRI is applied to predict MGMT promoter methylation status in GBMs. • GBMs with unmethylated MGMT promoter present higher APTw-MRI than methylated GBMs. • Multiple APTw histogram metrics can identify MGMT methylation status. • Mean APTw values showed the highest diagnostic accuracy (AUC = 0.825).

PARADIGM-2: Two parallel phase I studies of olaparib and radiotherapy or olaparib and radiotherapy plus temozolomide in patients with newly diagnosed glioblastoma, with treatment stratified by MGMT status

Glioblastoma has a dismal prognosis and molecular targeted agents have failed to improve outcomes to date. PARADIGM-2 is a phase I dose escalation study evaluating olaparib plus radiotherapy ± temozolomide in newly diagnosed glioblastoma, using MGMT methylation status to stratify patients and inform treatment schedules.

Correlation between MGMT promoter methylation and response to temozolomide-based therapy in neuroendocrine neoplasms: an observational retrospective multicenter study.

Temozolomide (TEM) based therapy has been reported being effective in the treatment of metastatic neuroendocrine neoplasms (NEN), with response rates ranging from 30 to 70%. Among patients affected by advanced glioblastoma or melanoma and treated with TEM, loss of tumoral O6-methylguanine DNA methyltransferase (MGMT) is correlated with improved survival. In NEN patients, the role of MGMT deficiency in predicting clinical outcomes of TEM treatment is still under debate. In this study we evaluated 95 patients with advanced NENs undergoing treatment with TEM-based therapy. MGMT promoter methylation status was evaluated with two techniques: methylation specific-polymerase chain reaction or pyrosequencing. Treatment with TEM-based therapy was associated with an overall response rate of 27.4% according to RECIST criteria (51.8% of patients with and 17.7% without MGMT promoter methylation). Response to therapy, progression free survival and overall survival was correlated to MGMT status at univariate and multivariate analysis. Methylation of MGMT promoter could be a strong predictive factor of objective response and an important prognostic factor of a longer PFS and OS. According to our results, MGMT methylation status, evaluated with methylation specific-polymerase chain reaction or pyrosequencing, should have an important role in patients with metastatic NENs, in order to guide therapeutic options. These results need further confirmation with prospective studies.

Promoter methylation and expression of DNA repair genes MGMT and ERCC1 in tissue and blood of rectal cancer patients

Rectal cancer involves one-third of colorectal cancers (CRCs). Recently, data supported that DNA methylation have a role in CRC pathogenesis. In the present study we aimed to analyze the methylation status of MGMT and ERCC1 promoter regions in blood and tissue of patients with benign and malignant rectal tumors. We also studied the methylated MGMT and ERCC1 genes and their relations with clinicopathological features. Furthermore, we suggested that methylation may play a critical function in the regulation of MGMT and ERCC1 expression.Fifty patients with non-metastatic cancer rectum and 43 patients with benign rectal lesions were involved in the study. DNA extraction from blood and rectal specimens was done to analyze the methylation status of MGMT and ERCC1 genes by methylation-specific PCR method. RNA was extracted also to determine the expression levels of these genes by real time-PCR.The frequency of MGMT and ERCC1 methylation was significantly higher in rectum cancers than in benign tumors both for the tissue and the blood (p<0.001). There was no relation between MGMT or ERCC1 methylation and clinicopathological features; while they were correlated with the response to therapy. An interesting finding that the agreement of the methylation levels in the blood and rectal tissue was classified as good (κ=0.78) for MGMT gene and as very good (κ=0.85) for ERCC1. Lastly, the MGMT and ERCC1 genes methylation was associated with down-regulation of their mRNA expression when compared with the non-methylated status.Our findings provided evidence that both blood and tumor tissue MGMT and ERCC1 methylation were associated with cancer rectum. MGMT or ERCC1 methylation in blood could be suitable non-invasive biomarkers differentiating benign and malignant rectal tumors. Furthermore, the methylation of the MGMT and ERCC1 promoter regions was associated with down-regulation of their mRNA expression.

Glucocorticoids promote a glioma stem cell-like phenotype and resistance to chemotherapy in human glioblastoma primary cells: Biological and prognostic significance.

Glioma stem cells (GSCs) are glioblastoma (GBM) cells that are resistant to therapy and can give rise to recurrent tumors. The identification of patient-related factors that support GSCs is thus necessary to design effective therapies for GBM patients. Glucocorticoids (GCs) are used to treat GBM-associated edema. However, glucocorticoids participate in the physiological response to psychosocial stress, which has been linked to poor cancer prognosis. This raises concern that glucocorticoids affect the tumor and GSCs. Here, we treated primary human GBM cells with dexamethasone and evaluated GC-driven changes in cell morphology, proliferation, migration, gene expression, secretory activity and growth as neurospheres. Dexamethasone treatment of GBM cells appeared to promote the development of a GSC-like phenotype and conferred resistance to physiological stress and chemotherapy. We also analyzed a potential correlation between GC treatment and tumor recurrence after surgical excision in a population-based consecutive cohort of 48 GBM patients, adjusted for differences in known prognostic factors concerning baseline and treatment characteristics. In this cohort, we found a negative correlation between GC intake and progression-free survival, regardless of the MGMT methylation status. In conclusion, our findings raise concern that treatment of GBM with GCs may compromise the efficacy of chemotherapy and may support a GSC population, which could contribute to tumor recurrence and the poor prognosis of the disease.

ACTR-27. COMPLIANCE AND TREATMENT DURATION PREDICT SURVIVAL IN A PHASE 3 EF-14 TRIAL OF TUMOR TREATING FIELDS WITH TEMOZOLOMIDE IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

AbstractTumor treating fields (TTFields) are a physical anti-mitotic treatment modality characterized by their immediate mode of action and lack of a half-life. It has been shown previously that average monthly compliance with TTFields is correlated with overall survival in recurrent glioblastoma. A ≥75% compliance, i.e. an average daily use of at least 18h/d, has been suggested as a target for patients with recurrent glioblastoma when receiving TTFields as monotherapy. In the EF-14 phase 3 trial in newly diagnosed glioblastoma, TTFields were applied together with temozolomide (TTFields/TMZ) and led to superior progression free (PFS) and overall survival (OS) compared to TMZ alone. Patients in the TTFields/TMZ arm received TTFields for a median of 8.2 months (95%CI 7.9–9.3), with 13%, 3%, 1% and 90% compliance: PFS HR 0.54 95%CI 0.37–0.79; OS HR 0.52 95%CI 0.35–0.79). A Cox model controlling for gender, extent of resection, MGMT methylation status, age, region and performance status indicated compliance is independent of these factors (HR 0.78; p=0.031; for OS at compliance ≥75% vs <75%). In conclusion, in the EF-14 trial a compliance threshold of 50% with TTFields treatment was correlated with significantly improved outcomes. The results clearly show that the higher patients’ compliance with TTFields, the better their outcomes. This effect was independent of other prognostic factors such as performance status, age and MGMT methylation.

NIMG-43. GLIOMA PATIENT OUTCOME AND TUMOR BIOLOGY CORRELATE WITH INTRAOPERATIVE MRI FLAIR AND T2 TUMOR VOLUMES COMPARED WITH IMMEDIATE AND 3 MONTH POSTOPERATIVE VOLUMES

AbstractINTRODUCTIONIntraoperative MRI is a useful tool in the operative management of human gliomas. T2 and FLAIR signals are often used as resection margins. We hypothesized that intraoperatively obtained MRI T2 and FLAIR signal volumes might not reflect corresponding post-operative volumes due to tumor edema after resection and brain manipulation.METHODSWe examined 160 patients, average age 48.0 (range 16-82) 71 females and 89 males, who underwent intraoperative imaging during glioma surgery. We excluded patients with a new vascular injury identified on diffusion-weighted imaging. Volumetric assessment of T2 and FLAIR signals were made with OSRIX image analysis program and ratios calculated for intraoperative, immediate and 3 month post-operative images for each patient. This was correlated with tumor histology and various molecular markers including IDH-1 mutation and MGMT methylation status as well a patient progression-free and overall survival.RESULTSWe examined 13 grade I gliomas (DNET, ganglioglioma, JPA) with postop/intraop FLAIR and T2 ratios of roughly 3. In a similar fashion we found that ratios of FLAIR and T2 images for grade 2 tumors (29 LGA, 16 oligo) averaged around 3-4 times larger for immediate and 3 months post op images. A similar ratio was found for high-grade gliomas, (17 AA, 10 AO and 75 GBM). Molecular markers did not predict imaging volume ratios.CONCLUSIONSPostoperative FLAIR and T2 signal volumes are significantly higher than intraoperatively obtained corresponding volumes for most gliomas studied. Further work will be required but this study questions the validity of T2 and FLAIR images obtained intraoperatively.

Pseudoprogression as an adverse event of glioblastoma therapy.

We explored predictive factors of pseudoprogression (PsP) and its impact on prognosis in a retrospective series of uniformly treated glioblastoma patients. Patients were classified as having PsP, early progression (eP) or neither (nP). We examined potential associations with clinical, molecular, and basal imaging characteristics and compared overall survival (OS), progression‐free survival (PFS), post‐progression survival (PPS) as well as the relationship between PFS and PPS in the three groups. Of the 256 patients studied, 56 (21.9%) were classified as PsP, 70 (27.3%) as eP, and 130 (50.8%) as nP. Only MGMT methylation status was associated to PsP. MGMT methylated patients had a 3.5‐fold greater possibility of having PsP than eP (OR: 3.48; 95% CI: 1.606–7.564; P = 0.002). OS was longer for PsP than eP patients (18.9 vs. 12.3 months; P = 0.0001) but was similar for PsP and nP patients (P = 0.91). OS was shorter–though not significantly so—for PsP than nP patients (OS: 19.5 vs. 27.9 months; P = 0.63) in methylated patients. PPS was similar for patients having PsP, eP or nP (PPS: 7.2 vs. 5.4 vs. 6.7; P = 0.43). Neurological deterioration occurred in 64.3% of cases at the time they were classified as PsP and in 72.8% of cases of eP (P = 0.14). PsP confounds the evaluation of disease and does not confer a survival advantage in glioblastoma.

Comparative assessment of three methods to analyze MGMT methylation status in a series of 350 gliomas and gangliogliomas

MGMT promoter methylation is considered as a prognostic and predictive biomarker indicating response to chemotherapy and radiotherapy in glioblastoma. A number of different methods and platforms including pyrosequencing (PSQ), quantitative methylation-specific PCR (qMSP) and immunohistochemistry (IHC), methylation-sensitive high resolution melting (MS-HRM) and NGS (Next Generation Sequencing) have been used to detect MGMT promoter methylation in gliomas. However, controversy remains about the most appropriate method to use for analyzing MGMT status. The MGMT promoter methylation status of a total of 350 gliomas and gangliogliomas was examined using PSQ, qMSP and IHC in parallel. Using PSQ as a recommended standard method, the sensitivity, specificity, positive/negative predictive value and correlation with the other assays were calculated. Among 350 glioma and ganglioglioma cases, the MGMT promoter tested positive for methylation in 53.1%, 55.4%, and 70.3% of the cases by PSQ, qMSP and IHC, respectively. The sensitivity and specificity of qMSP were 97.8% and 92.7%, respectively. Twelve cases that tested positive for methylation using qMSP were negative according to PSQ, and four cases that were negative according to qMSP tested positive according to PSQ. The concordance rate between PSQ and qMSP was 90.8%. The sensitivity and specificity of IHC for the detection of MGMT at the protein level were 84.4% and 45.7%, respectively. The concordance rate between PSQ and IHC was 30.8%.This study demonstrated that qMSP is an effective and rapid detection method for routine use in pathology laboratories for the identification of MGMT promoter methylation. A combination of IHC and qMSP assays can provide high sensitivity and specificity for the prediction of MGMT status. A few cases that tested negative with PSQ did harbor MGMT promoter methylation, as confirmed by qMSP and sequencing, and this subgroup of patients may benefit from temozolomide.