Ahmed Idbaih

Isocitrate Dehydrogenase 1 Codon 132 Mutation Is an Important Prognostic Biomarker in Gliomas

PURPOSE Unexpected mutations affecting the isocitrate dehydrogenase (IDH1) gene at codon 132 have been found in 12% of glioblastomas. PATIENTS AND METHODS IDH1 codon 132 sequencing was performed in a series of 404 patients with glioma (100 grade 2, 121 grade 3, and 183 grade 4 gliomas) and correlated with histology, genomic profile, methylguanyl methyltransferase (MGMT) promoter methylation status, and outcome. RESULTS A total of 155 codon 132 mutations were found, of which 131 were Arg132His (88.5%). The IDH1 mutation was inversely correlated with grade, affecting 77% of grade 2, 55% of grade 3, and 6% of grade 4 gliomas (P < 10(-15)). The IDH1 mutation was tightly associated with a 1p19q codeleted genotype (P < 10(-14)) and an MGMT methylated status (P < .001) but mutually exclusive with EGFR amplification (P < 10(-15)) and loss of chromosome 10 (P < 10(-15)). The presence (v absence) of IDH1 mutation was associated with a better outcome in grade 2 (150.9 v 60.1 months, respectively; P = .01), grade 3 (81.1 v 19.4 months, respectively; P < .001), and grade 4 gliomas (27.4 v 14 months, respectively; P < .01). After adjustment for grade, age, MGMT status, genomic profile, and treatment, multivariate analysis confirmed that IDH1 mutation was an independent favorable prognostic marker (hazard ratio = 0.297; 95% CI, 0.157 to 0.564, P = .00021). CONCLUSION This study indicates that IDH1 codon 132 mutation is closely linked to the genomic profile of the tumor and constitutes an important prognostic marker in grade 2 to 4 gliomas.

Genome-wide association study identifies five susceptibility loci for glioma.

To identify risk variants for glioma, we conducted a meta-analysis of two genome-wide association studies by genotyping 550K tagging SNPs in a total of 1,878 cases and 3,670 controls, with validation in three additional independent series totaling 2,545 cases and 2,953 controls. We identified five risk loci for glioma at 5p15.33 (rs2736100, TERT; P = 1.50 × 10−17), 8q24.21 (rs4295627, CCDC26; P = 2.34 × 10−18), 9p21.3 (rs4977756, CDKN2A-CDKN2B; P = 7.24 × 10−15), 20q13.33 (rs6010620, RTEL1; P = 2.52 × 10−12) and 11q23.3 (rs498872, PHLDB1; P = 1.07 × 10−8). These data show that common low-penetrance susceptibility alleles contribute to the risk of developing glioma and provide insight into disease causation of this primary brain tumor.

IDH1 and IDH2 Mutations Are Prognostic but not Predictive for Outcome in Anaplastic Oligodendroglial Tumors: A Report of the European Organization for Research and Treatment of Cancer Brain Tumor Group

Purpose: Recent studies have shown the prognostic significance of IDH1 mutations in glioma. It is yet unclear if IDH1 mutations are predictive for outcome to chemotherapy. We determined the effect of IDH1 mutations on progression-free survival and overall survival (OS), and its correlation with other clinical and molecular features in the prospective randomized European Organization for Research and Treatment of Cancer study 26951 on adjuvant procarbazine, 1-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea, and vincristine (PCV) in anaplastic oligodendroglioma. Experimental Design: IDH1 and IDH2 alterations of the mutational hotspot codons R132 and R172 were assessed by the bidirectional cycle sequencing of PCR-amplified fragments. MGMT promoter methylation was assessed using methylation-specific multiplex ligation–dependant probe amplification based on methylation-sensitive restriction analysis. Loss of chromosomes 1p, 19q, 10, and 10q and the gain of 7 and the EGFR gene were assessed with fluorescence in situ hybridization. Results: From 159 patients, sufficient material was available for IDH1 analysis. In 151 and 118 of these patients, respectively, the 1p/19q status and the MGMT promoter methylation status were known. In 73 cases (46%), an IDH1 mutation was found and only one IDH2 mutation was identified. The presence of IDH1 mutations correlated with 1p/19q codeletion and MGMT promoter methylation, and inversely correlated with loss of chromosome 10, EGFR amplification, polysomy of chromosome 7, and the presence of necrosis. IDH1 mutations were found to be prognostic in the radiotherapy- and the radiotherapy/PCV-treated patients, for both progression-free survival and OS. With Cox proportional hazard modeling for OS with stepwise selection, IDH1 mutations and 1p/19q codeletion but not MGMT promoter methylation were independent prognostic factors. Conclusion: In this homogeneously treated group of anaplastic oligodendroglioma patients, the presence of IDH1 mutations was found to carry a very strong prognostic significance for OS but without evidence of a predictive significance for outcome to PCV chemotherapy. IDH1 mutations were strongly associated with 1p/19q codeletion and MGMT promoter methylation. Clin Cancer Res; 16(5); 1597–604

Maintenance Therapy With Tumor-Treating Fields Plus Temozolomide vs Temozolomide Alone for Glioblastoma: A Randomized Clinical Trial

IMPORTANCE Glioblastoma is the most devastating primary malignancy of the central nervous system in adults. Most patients die within 1 to 2 years of diagnosis. Tumor-treating fields (TTFields) are a locoregionally delivered antimitotic treatment that interferes with cell division and organelle assembly. OBJECTIVE To evaluate the efficacy and safety of TTFields used in combination with temozolomide maintenance treatment after chemoradiation therapy for patients with glioblastoma. DESIGN, SETTING, AND PARTICIPANTS After completion of chemoradiotherapy, patients with glioblastoma were randomized (2:1) to receive maintenance treatment with either TTFields plus temozolomide (n = 466) or temozolomide alone (n = 229) (median time from diagnosis to randomization, 3.8 months in both groups). The study enrolled 695 of the planned 700 patients between July 2009 and November 2014 at 83 centers in the United States, Canada, Europe, Israel, and South Korea. The trial was terminated based on the results of this planned interim analysis. INTERVENTIONS Treatment with TTFields was delivered continuously (>18 hours/day) via 4 transducer arrays placed on the shaved scalp and connected to a portable medical device. Temozolomide (150-200 mg/m2/d) was given for 5 days of each 28-day cycle. MAIN OUTCOMES AND MEASURES The primary end point was progression-free survival in the intent-to-treat population (significance threshold of .01) with overall survival in the per-protocol population (n = 280) as a powered secondary end point (significance threshold of .006). This prespecified interim analysis was to be conducted on the first 315 patients after at least 18 months of follow-up. RESULTS The interim analysis included 210 patients randomized to TTFields plus temozolomide and 105 randomized to temozolomide alone, and was conducted at a median follow-up of 38 months (range, 18-60 months). Median progression-free survival in the intent-to-treat population was 7.1 months (95% CI, 5.9-8.2 months) in the TTFields plus temozolomide group and 4.0 months (95% CI, 3.3-5.2 months) in the temozolomide alone group (hazard ratio [HR], 0.62 [98.7% CI, 0.43-0.89]; P = .001). Median overall survival in the per-protocol population was 20.5 months (95% CI, 16.7-25.0 months) in the TTFields plus temozolomide group (n = 196) and 15.6 months (95% CI, 13.3-19.1 months) in the temozolomide alone group (n = 84) (HR, 0.64 [99.4% CI, 0.42-0.98]; P = .004). CONCLUSIONS AND RELEVANCE In this interim analysis of 315 patients with glioblastoma who had completed standard chemoradiation therapy, adding TTFields to maintenance temozolomide chemotherapy significantly prolonged progression-free and overall survival. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00916409.

IDH1 or IDH2 mutations predict longer survival and response to temozolomide in low-grade gliomas.

Objectives: Recent studies have shown that IDH1 and IDH2 mutations occur frequently in gliomas, including low-grade gliomas. However, their impact on the prognosis and chemosensitivity of low-grade gliomas remains unclear. Methods: Search for IDH1 and IDH2 mutations, loss of heterozygosity on chromosomes 1p and 19q, MGMT promoter methylation, and p53 expression was performed in a series of 271 low-grade gliomas and correlated with overall survival. A subgroup of 84 patients treated up-front with temozolomide was individualized. Response to temozolomide was evaluated by progression-free survival, as well as by tumor size on successive MRI scans, and then correlated with molecular alterations. Results: IDH (IDH1 or IDH2) mutations were found in 132/189 patients (70%). IDH mutation and 1p-19q codeletion were associated with prolonged overall survival in univariate (p = 0.002 and p = 0.0001) and multivariate analysis (p = 0.003 and p = 0.004). 1p-19q codeletion, MGMT promoter methylation, and IDH mutation (p = 0.01) were correlated with a higher rate of response to temozolomide. Further analysis of the course of the disease prior to any treatment except for surgery (untreated subgroup) showed that 1p-19q codeletion was associated with prolonged progression-free survival in univariate analysis, whereas IDH mutation was not. Conclusion: IDH mutation appears to be a significant marker of positive prognosis and chemosensitivity in low-grade gliomas, independently of 1p-19q codeletion, whereas its impact on the course of untreated tumors seems to be limited.

Temozolomide for low-grade gliomas Predictive impact of 1p/19q loss on response and outcome

Objective: To evaluate the predictive impact of chromosome 1p/19q deletions on the response and outcome of progressive low-grade gliomas (LGG) treated with up-front temozolomide (TMZ) chemotherapy. Methods: Adult patients with measurable, progressive LGG (WHO grade II) treated with TMZ delivered at the conventional schedule (200 mg/m2/day for 5 consecutive days, repeated every 28 days) were retrospectively evaluated for response by central review of MRI-s. Chromosome 1p and 19q deletions were detected by the loss of the heterozygosity technique (LOH). Results: A total of 149 consecutive patients were included in this retrospective, single center observational study. The median number of TMZ cycles delivered was 14 (range 2 to 30). Seventy-seven patients (53%) experienced an objective response (including 22 [15%] cases of partial response and 55 [38%] cases of minor response), 55 (37%) patients had stable disease, and 14 (10%) had a progressive disease. The median time to maximum tumor response was 12 months (range 3 to 30 months). The median progression-free survival (PFS) was 28 months (95% CI: 23.4 to 32.6). Material for genotyping was available for 86 patients. Combined 1p/19q LOH was present in 42% of the cases and was significantly associated with a higher rate (p = 0.02) and longer objective response to chemotherapy (p = 0.017), and both longer PFS (p = 4.10−5) and overall survival (p = 0.04). Conclusion: Low-grade gliomas respond to temozolomide and loss of chromosome 1p/19q predicts both a durable chemosensitivity and a favorable outcome.

A new alternative mechanism in glioblastoma vascularization: tubular vasculogenic mimicry

Glioblastoma is one of the most angiogenic human tumours and endothelial proliferation is a hallmark of the disease. A better understanding of glioblastoma vasculature is needed to optimize anti-angiogenic therapy that has shown a high but transient efficacy. We analysed human glioblastoma tissues and found non-endothelial cell-lined blood vessels that were formed by tumour cells (vasculogenic mimicry of the tubular type). We hypothesized that CD133+ glioblastoma cells presenting stem-cell properties may express pro-vascular molecules allowing them to form blood vessels de novo. We demonstrated in vitro that glioblastoma stem-like cells were capable of vasculogenesis and endothelium-associated genes expression. Moreover, a fraction of these glioblastoma stem-like cells could transdifferentiate into vascular smooth muscle-like cells. We describe here a new mechanism of alternative glioblastoma vascularization and open a new perspective for the antivascular treatment strategy.

All the 1p19q codeleted gliomas are mutated on IDH1 or IDH2

Background: Recently, the gene encoding the human cytosolic NADPH-dependent isocitrate dehydrogenase (IDH1) was reported frequently mutated in gliomas. Rare mutations were also found in the sequence of the mitochondrial isoform IDH2. Methods: In a series of 764 gliomas genome-wide characterized, we determined the presence of mutations in the sequences of both IDH1 and IDH2 genes by direct sequencing. Results: We found that all tumors with complete 1p19q codeletion (n = 128) were mutated in the IDH1 (118) or IDH2 (10) gene. This 100% mutation rate contrasted strikingly with other gliomas exhibiting either variable 1p and 19q alterations (n = 159, IDH1/IDH2 mutation rate of 33%) or no 1p19q alteration (n = 477, IDH1/IDH2 mutation rate 32%). Our data also confirm the prognostic impact of IDH1/IDH2 mutation in gliomas whatever grade considered: patients harboring mutations of IDH1/IDH2 have an improved median overall survival. Moreover, in WHO grade II and III gliomas, 3 groups with significantly different outcomes were identified according to their 1p19q and IDH1/IDH2 statuses. Tumors carrying both alterations had longer overall survival than their nonmutated counterpart. Conclusions: This exclusive association suggests a new mechanism of tumorigenesis. Perhaps the IDH1/IDH2 mutation is a prerequisite for the occurrence of the t(1;19) translocation, or it is required for the 1p19q codeleted cells to acquire a tumor phenotype.

MRI of Clot in Cerebral Venous Thrombosis High Diagnostic Value of Susceptibility-Weighted Images

Background and Purpose— In cerebral venous thrombosis (CVT), the sensitivity of conventional MRI sequences to detect clot in the sinuses or veins is incomplete and largely depends on the time elapsed since thrombus formation. Little is known concerning the corresponding diagnostic value of fluid-attenuated inversion recovery (FLAIR), echo-planar T2* susceptibility-weighted imaging (T2*SW) or diffusion-weighted images (DWI). Methods— We performed a retrospective analysis of 114 MRI examinations from 39 patients with CVT using a structured assessment. The time course of sensitivity in the detection of clot (n=166 clots) was analyzed for different MR sequences using a multilevel logistic model. The sensitivity of different MR sequences for diagnosis of cortical venous thrombosis was tested separately (n=38 clots). Results— The sensitivity of T2*SW and T1-weighted spin echo image (T1SE) sequences to detect clot in the sinuses or veins was estimated at 90% and 71% between day 1 and day 3, which was much higher than that of T2SE, FLAIR or DWI during the first week of clinical onset. The sensitivity of T2*SW was stable in the first week. After this period, the sensitivity of T2*SW decreased less than that of T1SE. Thrombosed cortical veins, even in the absence of visible occlusion on magnetic resonance venography, were detected more frequently with T2*SW (97%) and T1SE (78%) than with FLAIR or DWI (<40%). Conclusions— T2*SW imaging appears to be of additional diagnostic value in CVT. The T2*SW sequence may be particularly useful during the acute phase of CVT when the sensitivity of the other sequences is incomplete and for the diagnosis of isolated cortical venous thrombosis.

Two Types of Chromosome 1p Losses with Opposite Significance in Gliomas

Deletion of the short arm of chromosome 1 (1p) is considered a favorable prognostic factor in glial tumors. High‐density array‐comparative genomic hybridization analysis of 108 gliomas shows two distinct types of 1p deletions. Complete hemizygous losses of 1p, which are tightly associated with 19q loss and oligodendroglial phenotype, and partial 1p deletions mainly observed in astrocytic tumors and not associated with 19q loss. Whereas the first type predicts longer overall and progression‐free survival (p < 0.0001), the second type has a pejorative prognostic value. Complete 1p‐arm evaluation therefore is required to appreciate the real clinical significance of 1p loss in gliomas. Ann Neurol 2005;58:483–487