Genomic profiling reveals distinctive molecular relapse patterns in IDH1/2 wild-type glioblastoma.

Molecular changes associated with the progression of glioblastoma after standard radiochemotherapy remain poorly understood. We compared genomic profiles of 27 paired primary and recurrent IDH1/2 wild-type glioblastomas by genome-wide array-based comparative genomic hybridization. By bioinformatic analysis, primary and recurrent tumor profiles were normalized and segmented, chromosomal gains and losses identified taking the tumor cell content into account, and difference profiles deduced. Seven of 27 (26%) pairs lacked DNA copy number differences between primary and recurrent tumors (equal pairs). The recurrent tumors in 9/27 (33%) pairs contained all chromosomal imbalances of the primary tumors plus additional ones, suggesting a sequential acquisition of and/or selection for aberrations during progression (sequential pairs). In 11/27 (41%) pairs, the profiles of primary and recurrent tumors were divergent, i.e., the recurrent tumors contained additional aberrations but had lost others, suggesting a polyclonal composition of the primary tumors and considerable clonal evolution (discrepant pairs). Losses on 9p21.3 harboring the CDKN2A/B locus were significantly more common in primary tumors from sequential and discrepant (nonequal) pairs. Nonequal pairs showed ten regions of recurrent genomic differences between primary and recurrent tumors harboring 46 candidate genes associated with tumor recurrence. In particular, copy numbers of genes encoding apoptosis regulators were frequently changed at progression. In summary, approximately 25% of IDH1/2 wild-type glioblastoma pairs have stable genomic imbalances. In contrast, approximately 75% of IDH1/2 wild-type glioblastomas undergo further genomic aberrations and alter their clonal composition upon recurrence impacting their genomic profile, a process possibly facilitated by 9p21.3 loss in the primary tumor. © 2014 Wiley Periodicals, Inc.

Molecular characterization of long-term survivors of glioblastoma using genome- and transcriptome-wide profiling.

The prognosis of glioblastoma, the most malignant type of glioma, is still poor, with only a minority of patients showing long-term survival of more than three years after diagnosis. To elucidate the molecular aberrations in glioblastomas of long-term survivors, we performed genome- and/or transcriptome-wide molecular profiling of glioblastoma samples from 94 patients, including 28 long-term survivors with >36 months overall survival (OS), 20 short-term survivors with <12 months OS and 46 patients with intermediate OS. Integrative bioinformatic analyses were used to characterize molecular aberrations in the distinct survival groups considering established molecular markers such as isocitrate dehydrogenase 1 or 2 (IDH1/2) mutations, and O(6) -methylguanine DNA methyltransferase (MGMT) promoter methylation. Patients with long-term survival were younger and more often had IDH1/2-mutant and MGMT-methylated tumors. Gene expression profiling revealed over-representation of a distinct (proneural-like) expression signature in long-term survivors that was linked to IDH1/2 mutation. However, IDH1/2-wildtype glioblastomas from long-term survivors did not show distinct gene expression profiles and included proneural, classical and mesenchymal glioblastoma subtypes. Genomic imbalances also differed between IDH1/2-mutant and IDH1/2-wildtype tumors, but not between survival groups of IDH1/2-wildtype patients. Thus, our data support an important role for MGMT promoter methylation and IDH1/2 mutation in glioblastoma long-term survival and corroborate the association of IDH1/2 mutation with distinct genomic and transcriptional profiles. Importantly, however, IDH1/2-wildtype glioblastomas in our cohort of long-term survivors lacked distinctive DNA copy number changes and gene expression signatures, indicating that other factors might have been responsible for long survival in this particular subgroup of patients.

Lymph node and tumor-associated PD-L1+ macrophages antagonize dendritic cell vaccines by suppressing CD8+ T cells.

Current immunotherapies provide limited benefits against T cell-depleted tumors, calling for therapeutic innovation. Using multi-omics integration of cancer patient data, we predict a type I interferon (IFN) responseHIGH state of dendritic cell (DC) vaccines, with efficacious clinical impact. However, preclinical DC vaccines recapitulating this state by combining immunogenic cancer cell death with induction of type I IFN responses fail to regress mouse tumors lacking T cell infiltrates. Here, in lymph nodes (LNs), instead of activating CD4+/CD8+ T cells, DCs stimulate immunosuppressive programmed death-ligand 1-positive (PD-L1+) LN-associated macrophages (LAMs). Moreover, DC vaccines also stimulate PD-L1+ tumor-associated macrophages (TAMs). This creates two anatomically distinct niches of PD-L1+ macrophages that suppress CD8+ T cells. Accordingly, a combination of PD-L1 blockade with DC vaccines achieves significant tumor regression by depleting PD-L1+ macrophages, suppressing myeloid inflammation, and de-inhibiting effector/stem-like memory T cells. Importantly, clinical DC vaccines also potentiate T cell-suppressive PD-L1+ TAMs in glioblastoma patients. We propose that a multimodal immunotherapy and vaccination regimen is mandatory to overcome T cell-depleted tumors.

Migration of mesenchymal stem cells towards glioblastoma cells depends on hepatocyte-growth factor and is enhanced by aminolaevulinic acid-mediated photodynamic treatment.

Hepatocyte-growth factor (HGF) is expressed by glioblastomas and contributes to their growth, migration and invasion. HGF also mediates migration of mesenchymal stem cells (MSC) to sites of apoptotic cell death. Moreover, MSC show tropism for glioblastomas, which is exploited in gene therapy to deliver the therapeutics to the tumor cells. Here, we have studied whether HGF contributes to the recruitment of MSC by glioblastoma cells and whether aminolaevulinic acid-mediated photodynamic therapy (ALA/PDT), a novel therapeutic approach that induces apoptosis in glioblastoma cells, affects HGF release and this migratory response. MSC expressed the HGF receptor MET and migrated towards U87 and U251 glioblastoma spheroids. Migration increased significantly when spheroids were subjected to ALA/PDT, which was associated with induction of apoptosis and up-regulation of HGF. Neutralizing HGF resulted in significant inhibition of MSC migration towards untreated as well as ALA/PDT-treated spheroids. Thus, glioblastoma cells express HGF, which contributes to the attraction of MSC. ALA/PDT induces apoptosis and augments HGF release causing enhanced MSC migration towards the tumor cells. ALA/PDT may therefore be exploited to improve targeting of MSC delivered gene therapy, but it may also constitute a risk in terms of beneficial effects for the tumor.

Multiomics and spatial mapping characterizes human CD8+ T cell states in cancer.

Clinically relevant immunological biomarkers that discriminate between diverse hypofunctional states of tumor-associated CD8+ T cells remain disputed. Using multiomics analysis of CD8+ T cell features across multiple patient cohorts and tumor types, we identified tumor niche-dependent exhausted and other types of hypofunctional CD8+ T cell states. CD8+ T cells in "supportive" niches, like melanoma or lung cancer, exhibited features of tumor reactivity-driven exhaustion (CD8+ TEX). These included a proficient effector memory phenotype, an expanded T cell receptor (TCR) repertoire linked to effector exhaustion signaling, and a cancer-relevant T cell-activating immunopeptidome composed of largely shared cancer antigens or neoantigens. In contrast, "nonsupportive" niches, like glioblastoma, were enriched for features of hypofunctionality distinct from canonical exhaustion. This included immature or insufficiently activated T cell states, high wound healing signatures, nonexpanded TCR repertoires linked to anti-inflammatory signaling, high T cell-recognizable self-epitopes, and an antiproliferative state linked to stress or prodeath responses. In situ spatial mapping of glioblastoma highlighted the prevalence of dysfunctional CD4+:CD8+ T cell interactions, whereas ex vivo single-cell secretome mapping of glioblastoma CD8+ T cells confirmed negligible effector functionality and a promyeloid, wound healing-like chemokine profile. Within immuno-oncology clinical trials, anti-programmed cell death protein 1 (PD-1) immunotherapy facilitated glioblastoma's tolerogenic disparities, whereas dendritic cell (DC) vaccines partly corrected them. Accordingly, recipients of a DC vaccine for glioblastoma had high effector memory CD8+ T cells and evidence of antigen-specific immunity. Collectively, we provide an atlas for assessing different CD8+ T cell hypofunctional states in immunogenic versus nonimmunogenic cancers.

Promoter methylation and expression of MGMT and the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2 in paired primary and recurrent glioblastomas.

Epigenetic silencing of the O(6) -methylguanine-DNA methyltransferase (MGMT) gene promoter is associated with prolonged survival in glioblastoma patients treated with temozolomide (TMZ). We investigated whether glioblastoma recurrence is associated with changes in the promoter methylation status and the expression of MGMT and the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2 in pairs of primary and recurrent glioblastomas of 80 patients, including 64 patients treated with radiotherapy and TMZ after the first operation. Among the primary tumors, the MGMT promoter was methylated in 31 patients and unmethylated in 49 patients. In 71 patients (89%), the MGMT promoter methylation status of the primary tumor was retained at recurrence. MGMT promoter methylation, but not MGMT protein expression, was associated with longer progression-free survival, overall survival and postrecurrence survival (PRS). Moreover, PRS was increased under salvage chemotherapy. Investigation of primary and recurrent glioblastomas of 43 patients did not identify promoter methylation in any of the four MMR genes. However, recurrent glioblastomas demonstrated significantly lower MSH2, MSH6 and PMS2 protein expression as detected by immunohistochemistry. In conclusion, reduced expression of MMR proteins, but not changes in MGMT promoter methylation, is characteristic of glioblastomas recurring after the current standards of care.

Molecular signatures classify astrocytic gliomas by IDH1 mutation status.

To identify novel glioma-associated pathomechanisms and molecular markers, we performed an array-based comparative genomic hybridization analysis of 131 diffuse astrocytic gliomas, including 87 primary glioblastomas (pGBIV), 13 secondary glioblastomas (sGBIV), 19 anaplastic astrocytomas (AAIII) and 12 diffuse astrocytomas (AII). All tumors were additionally screened for IDH1 and IDH2 mutations. Expression profiling was performed for 74 tumors (42 pGBIV, 11 sGBIV, 13 AAIII, 8 AII). Unsupervised and supervised bioinformatic analyses revealed distinct genomic and expression profiles separating pGBIV from the other entities. Classifier expression signatures were strongly associated with the IDH1 gene mutation status. Within pGBIV, the rare subtype of IDH1 mutant tumors shared expression profiles with IDH1 mutant sGBIV and was associated with longer overall survival compared with IDH1 wild-type tumors. In patients with IDH1 wild-type pGBIV, PDGFRA gain or amplification as well as 19q gain were associated with patient outcome. Array-CGH analysis additionally revealed homozygous deletions of the FGFR2 gene at 10q26.13 in 2 pGBIV, with reduced FGFR2 mRNA levels being frequent in pGBIV and linked to poor outcome. In conclusion, we report that diffuse astrocytic gliomas can be separated into 2 major molecular groups with distinct genomic and mRNA profiles as well as IDH1 gene mutation status. In addition, our results suggest FGFR2 as a novel glioma-associated candidate tumor suppressor gene on the long arm of chromosome 10.

Rapid and sensitive assessment of the IDH1 and IDH2 mutation status in cerebral gliomas based on DNA pyrosequencing.

Diffusely infiltrating cerebral gliomas frequently carry point mutations in codon 132 of the isocitrate dehydrogenase 1 (IDH1) gene or in codon 172 of the IDH2 gene, which are both clinically important as diagnostic and prognostic markers. Here, we report on a method that allows for the rapid detection of IDH1 and IDH2 mutations based on pyrosequencing. The method is applicable to routinely processed tissue specimens and provides quantitative mutation data within less than one working day. Due to its high sensitivity, the technique may also be used for the diagnostic assessment of IDH1 or IDH2 mutation in tissue samples with low tumor cell content, such as the infiltration zone of diffuse gliomas. Using pyrosequencing and/or conventional cycle sequencing of IDH1 and IDH2 in 262 gliomas, we confirm frequent mutations in diffuse astrocytic and oligodendroglial gliomas, corroborate a prognostic role for IDH1 mutation in primary glioblastomas and show that pleomorphic xanthoastrocytomas generally lack mutations in these genes.

Treatment-Related Uptake of O-(2-18F-Fluoroethyl)-l-Tyrosine and l-[Methyl-3H]-Methionine After Tumor Resection in Rat Glioma Models.

Assessment of residual tumor after resection of cerebral gliomas can be difficult with MRI and may be improved by amino acid PET. The aim of this experimental study was to investigate uptake of 2-18F-fluoroethyl-l-tyrosine (18F-FET) and l-[methyl-3H]-methionine (3H-MET) in residual tumor after surgery and possible false-positive uptake in treatment-related changes. Methods: F98 or GS-9L rat gliomas were implanted into the brain of 64 rats. Tumors were resected after 1 wk of tumor growth, and sham surgery was performed in an additional 10 animals. At different time points after surgery (1, 2, 3, 7, and 14-16 d), rats underwent ex vivo dual-tracer autoradiography using 18F-FET and 3H-MET. Histologic slices were evaluated by immunostaining for cell density and astrogliosis. Tracer uptake was quantified by lesion-to-brain ratios (L/B) at the rim of the resection cavity (considered treatment-related uptake) and in residual or recurrent tumor tissue. Four animals showing no residual tumor underwent PET 3 d after surgery to examine time-activity curves of 18F-FET uptake in treatment-related changes. Results: Treatment-related uptake with a mean L/B of 2.0 ± 0.3 for 18F-FET and a mean L/B of 1.7 ± 0.2 for 3H-MET was noted at the rim of the resection cavity in the first week after surgery, decreasing significantly by 14-16 d (P < 0.01). Treatment-related tracer uptake was significantly higher for 18F-FET than for 3H-MET (P < 0.001). Tracer uptake in rat gliomas exceeded treatment-related tracer uptake at all time points (P < 0.001), but the latter was in the range of human gliomas. Reactive astrogliosis was noted near the resection cavity from the second day after surgery. Time-activity curves of 18F-FET uptake in those areas revealed constantly increasing uptake. Conclusion: Surgery may induce significant treatment-related 18F-FET and 3H-MET uptake near the resection cavity in the first week after surgery, presumably caused by reactive astrogliosis. Treatment-related tracer uptake was less pronounced for 3H-MET, indicating that 11C-MET may be better suited for assessing the postoperative situation than 18F-FET. Assessment of residual tumor after surgery by amino acid PET seems to be more reliable after an interval of 14 d.

Accumulation of protoporphyrin IX in medulloblastoma cell lines and sensitivity to subsequent photodynamic treatment.

BACKGROUND: Medulloblastoma (MB) is the most common malignant primary brain tumor of childhood. High risk patients still have a poor outcome, and especially young patients suffer from standard therapy induced sequelae. Therefore, other therapeutic options need to be explored. In glioblastoma (GBM), application of 5-aminolaevulinic acid (5-ALA) results in selective accumulation of protoporphyrin IX (PPIX) in the tumor cells, which can be exploited during fluorescence-guided surgery to increase the extent of resection or for photodynamic therapy (PDT) induced phototoxicity. It is not entirely clear, whether MB cells accumulate PPIX and are sensitive to PDT. METHODS: Human MYC-amplified (Med8A and D283) and non-amplified (UW228-2 and ONS76) MB cell lines were incubated for 2, 4 or 6 h with increasing doses (0-100 µg/ml) of 5-ALA, and PPIX accumulation was determined by flow cytometry. To assess sensitivity to 5-ALA/PDT, cells were incubated with 5-ALA and subsequently exposed to laser light of 635 nm wavelength (18.75 J/cm2). After an additional 24 h culture period, viability of cells was quantified using the WST-1 assay. Expression of ferrochelatase was detected by reverse transcription and quantitative polymerase chain reaction. Ferrochelatase activity was quantified by measuring the enzymatic conversion of PPIX to zinc-protoporphyrin. Expression of the ABCG2 transporter protein CD338 was detected by flow cytometry. RESULTS: All MB cell lines showed a time- and dose-dependent accumulation of PPIX after exposure to exogenous 5-ALA and became sensitive to 5-ALA/PDT-induced phototoxicity. PPIX accumulation was reduced compared to U373 GBM cells at shorter incubation periods and limiting 5-ALA doses. Moreover, not all MB cells became PPIX positive and overall phototoxicity was lower in the MB cell lines. Notably, the MYC-amplified MB cells demonstrated a more pronounced photosensitivity compared to their non-amplified counterparts. There was no difference in expression of ferrochelatase, but enzymatic activity appeared to be reduced in the MB cells compared to U373 GBM cells, whereas CD338 was expressed on the MB cells only. CONCLUSION: Medulloblastoma cell lines accumulate PPIX after application of 5-ALA and become sensitive to PDT, associated with low ferrochelatase expression and activity. Photosensitivity is more pronounced in MYC-amplified cell lines. In contrast to GBM cells, however, PPIX accumulation appears to be reduced, restricted to a subset of cells and associated with lower photosensitivity of the MB cell lines, possibly due to expression of the ABCG2 transporter protein CD338 on MB cells.

Cellular immunity of patients with malignant glioma: prerequisites for dendritic cell vaccination immunotherapy.

OBJECT: Vaccination therapy that uses dendritic cells (DCs) is a promising immunotherapeutic approach. However, it relies on intact cellular immunity and efficient generation of mature DCs, both of which can be impaired in patients with glioma. Therefore, the immune status and ex vivo generation of DC in such patients were studied. METHODS: The frequencies of white blood cell subsets and monocyte-derived, mature DCs in patients with high-grade gliomas and healthy control volunteers were analyzed using flow cytometry. In the patients, frequencies of lymphocytes, T cells, and B cells were reduced in comparison with the volunteers in the control group, whereas frequencies of neutrophils and monocytes were increased. There were no differences between the two groups in terms of white blood cell counts or the frequency of NK cells and the major T-cell subsets. The responsiveness of T cells to lectin stimulation was normal. For monocytes, lower frequencies of CD80+ and CD86+ cells but not of CD40+ and HLA-DR+ cells were observed in patients. Ex vivo DC generation in a two-step culture protocol in autologous plasma-supplemented medium or in serum-free medium showed only minor differences in CD80 and HLA-DR expression between the patient and control groups. Frequencies of CD83+, CD1a+, CD14-, CD40+, and CD86+ cells were comparable. Overall, the serum-free medium was superior to the plasma-supplemented medium and allowed efficient ex vivo generation of CD83+, CD1a+, and CD14- mature DCs. CONCLUSIONS: Only minor defects in the immune status of patients with glioma were observed, which probably would not hamper immunotherapy. Mature DCs can be generated successfully in normal numbers and with typical immunophenotypes from monocytes of patients with glioma, particularly under serum-free conditions.

Human glioblastoma stem-like cells accumulate protoporphyrin IX when subjected to exogenous 5-aminolaevulinic acid, rendering them sensitive to photodynamic treatment.

Glioblastoma (GBM) is the most frequent and lethal primary brain tumor in adults. Despite multimodal therapy combining resection, radio- and alkylating chemotherapy, disease recurrence is universal and prognosis of patients is poor. Glioblastoma stem-like cells (GSC), which can be grown as neurospheres from primary tumors in vitro, appear to be resistant to the established therapies and are suspected to be the driving force for disease recurrence. Thus, efficacy of emerging therapies may depend on targeting GSC. 5-aminolaevulinic acid-mediated photodynamic therapy (5-ALA/PDT) is a promising therapeutic approach in GBM. It utilizes the selective accumulation of the photosensitizer protoporphyrin IX (PPIX) in GBM cells after application of 5-ALA. When exposed to laser light of 635nm wavelength, PPIX initiates a photochemical reaction resulting in the generation of reactive oxygen species, which kill the tumor cells. Whether GSC accumulate PPIX and are sensitive to 5-ALA/PDT is currently unknown. Therefore, human GSC were derived from primary tumors and grown as neurospheres under serum free conditions. When subjected to exogenous 5-ALA, a dose- and time-dependent accumulation of PPIX in GSC was observed by flow cytometry, which varied between individual GSC preparations. Subsequent exposure to laser light of 635nm wavelength substantially killed GSC, whereas treatment with 5-ALA or exposure to laser light only had no effect. LD50 values differed between GSC preparations, but were negatively correlated with PPIX accumulation in GSC. In summary, we report for the first time that glioblastoma stem-like cells accumulate PPIX when subjected to 5-aminolaevulinic acid and are sensitive to 5-aminolaevulinc acid based photodynamic therapy.

Complete resection of contrast-enhancing tumor volume is associated with improved survival in recurrent glioblastoma-results from the DIRECTOR trial.

BACKGROUND: The role of reoperation for recurrent glioblastoma (GBM) remains unclear. Prospective studies are lacking. Here, we studied the association of clinical outcome with extent of resection upon surgery for recurrent GBM in the patient cohort of DIRECTOR, a prospective randomized multicenter trial comparing 2 dose-intensified temozolomide regimens at recurrence of GBM. METHODS: We analyzed prospectively collected clinical and imaging data from the DIRECTOR cohort (N = 105). Volumetric analysis was performed on gadolinium contrast-enhanced MRI as well as fluid attenuated inversion recovery/T2 MRI and correlated with PFS after initial progression (PFS2) and post-recurrence survival (PRS). Quality of life was monitored by the EORTC QLQ-C30 and QLQ-BN20 questionnaires at 8-week intervals. RESULTS: Seventy-one patients received surgery at first recurrence. Prognostic factors, including age, MGMT promoter methylation, and Karnofsky performance score, were balanced between patients with and without reoperation. Outcome in patients with versus without surgery at recurrence was similar for PFS2 (2.0 mo vs 1.9 mo, P = .360) and PRS (11.4 mo vs 9.8 mo, P = .633). Among reoperated patients, post-surgery imaging was available in 59 cases. In these patients, complete resection of contrast-enhancing tumor (N = 40) versus residual detection of contrast enhancement (N = 19) was associated with improved PRS (12.9 mo [95% CI: 11.5-18.2] vs 6.5 mo [95% CI: 3.6-9.9], P < .001) and better quality of life. Incomplete tumor resection was associated with inferior PRS compared with patients who did not undergo surgery (6.5 vs 9.8 mo, P = .052). Quality of life was similar in these 2 groups. CONCLUSION: Surgery at first recurrence of GBM improves outcome if complete resection of contrast-enhancing tumor is achieved.

Long-term analysis of the NOA-04 randomized phase III trial of sequential radiochemotherapy of anaplastic glioma with PCV or temozolomide.

BACKGROUND: Optimal treatment and precise classification for anaplastic glioma are needed. METHODS: The objective for long-term follow-up of NOA-04 is to optimize the treatment sequence for patients with anaplastic gliomas. Patients were randomized 2:1:1 to receive the standard radiotherapy (RT) (arm A), procarbazine, lomustine and vincristine (PCV) (arm B1), or temozolomide (TMZ) (arm B2). RESULTS: Primary endpoint was time-to-treatment-failure (TTF), defined as progression after 2 lines of therapy or any time before if no further therapy was administered. Exploratory analyses examined associations of molecular marker status with TTF, progression-free survival (PFS), and overall survival (OS). At 9.5 (95% CI: 8.6-10.2) years, no difference between arms (A vs B1/B2) was observed: median TTF (4.6 [3.4-5.1] y vs 4.4 [3.3-5.3) y), PFS (2.5 [1.3-3.5] y vs 2.7 [1.9-3.2] y), and OS (8 [5.5-10.3] y vs 6.5 [5.4-8.3] y). Oligodendroglial versus astrocytic histology-but more so the subgroups according to CpG island methylator phenotype (CIMP) and 1p/19q co-deletion status-revealed a strong prognostic value of CIMPpos with (CIMPcodel) versus without 1p/19 co-deletion (CIMPnon-codel) versus CIMPneg. but no differential efficacy of RT versus chemotherapy for any of the endpoints. PFS was better for PCV- than for TMZ-treated patients with CIMPcodel tumors (HR B1 vs B2 0.39 [0.17-0.92], P = .031). In CIMPneg. tumors, hypermethylation of the O6-methyl-guanyl-DNA methyltransferase promoter (MGMT) provided a risk reduction for PFS with chemotherapy. CONCLUSIONS: There is no differential activity of primary chemotherapy versus RT in any subgroup of anaplastic glioma. Molecular diagnosis is superior to histology. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00717210.

MGMT Promoter Methylation Is a Strong Prognostic Biomarker for Benefit from Dose-Intensified Temozolomide Rechallenge in Progressive Glioblastoma: The DIRECTOR Trial.

PURPOSE: Rechallenge with temozolomide (TMZ) at first progression of glioblastoma after temozolomide chemoradiotherapy (TMZ/RT→TMZ) has been studied in retrospective and single-arm prospective studies, applying temozolomide continuously or using 7/14 or 21/28 days schedules. The DIRECTOR trial sought to show superiority of the 7/14 regimen. EXPERIMENTAL DESIGN: Patients with glioblastoma at first progression after TMZ/RT→TMZ and at least two maintenance temozolomide cycles were randomized to Arm A [one week on (120 mg/m(2) per day)/one week off] or Arm B [3 weeks on (80 mg/m(2) per day)/one week off]. The primary endpoint was median time-to-treatment failure (TTF) defined as progression, premature temozolomide discontinuation for toxicity, or death from any cause. O(6)-methylguanine DNA methyltransferase (MGMT) promoter methylation was prospectively assessed by methylation-specific PCR. RESULTS: Because of withdrawal of support, the trial was prematurely closed to accrual after 105 patients. There was a similar outcome in both arms for median TTF [A: 1.8 months; 95% confidence intervals (CI), 1.8-3.2 vs. B: 2.0 months; 95% CI, 1.8-3.5] and overall survival [A: 9.8 months (95% CI, 6.7-13.0) vs. B: 10.6 months (95% CI, 8.1-11.6)]. Median TTF in patients with MGMT-methylated tumors was 3.2 months (95% CI, 1.8-7.4) versus 1.8 months (95% CI, 1.8-2) in MGMT-unmethylated glioblastoma. Progression-free survival rates at 6 months (PFS-6) were 39.7% with versus 6.9% without MGMT promoter methylation. CONCLUSIONS: Temozolomide rechallenge is a treatment option for MGMT promoter-methylated recurrent glioblastoma. Alternative strategies need to be considered for patients with progressive glioblastoma without MGMT promoter methylation.

Oligodendroglial tumors: refinement of candidate regions on chromosome arm 1p and correlation of 1p/19q status with survival.

Loss of heterozygosity (LOH) on the chromosome arms 1p and 19q is frequent in oligodendroglial tumors and has been correlated with chemosensitivity and good prognosis in anaplastic oligodendrogliomas. The oligodendroglioma-associated tumor suppressor genes on 1p and 19q are as yet unknown. To narrow down candidate regions on 1p, we investigated oligodendroglial tumors from 89 patients for LOH at up to 30 polymorphic loci on 1p. In addition, all tumors were studied for LOH at 7 loci on 19q. Combined LOH on 1p and 19q was detected in 20 (83%) of 24 oligodendrogliomas, 15(63%) of 24 anaplastic oligodendrogliomas, 10 (56%) of 18 oligoastrocytomas, and 12 (52%) of 23 anaplastic oligoastrocytomas. Five tumors demonstrated partial deletions on 1p, which allowed to define 3 distinct candidate regions at 1p36.31-pter distal to D1S2633, 1p36.22-p36.31 between D1S489 and D1S2642, and 1p34.2-p36.1 between D1S2743 and D1S482, respectively. No partial deletions were detected on 19q. Combined LOH on 1p and 19q was associated with prolonged time to progression (TTP), longer overall survival (OS), and a higher 5-year survival rate. Depending on the presence or absence of combined LOH on 1p and 19q, patients with anaplastic oligodendroglial tumors treated with adjuvant radio- and/or chemotherapy showed a median TTP of 86 months versus 39 months, a median OS of 91 months versus 46 months, and a 5-year survival rate of 80% versus 36%, respectively. Similarly, LOH on 1p and 19q was associated with longer survival in patients with low-grade oligodendroglial tumors (TTP: 57 months versus 47 months; OS: 172 months versus 105 months; 5-year survival rate: 92% versus 70%). Thus, our results refine the location of putative oligodendroglioma suppressor genes on 1p and support the significance of LOH on 1p and 19q as a favorable prognostic marker.

MiR-328 promotes glioma cell invasion via SFRP1-dependent Wnt-signaling activation.

Background Diffusely infiltrative growth of human astrocytic gliomas is one of the major obstacles to successful tumor therapy. Thorough insights into the molecules and pathways signaling glioma cell invasion thus appear of major relevance for the development of targeted and individualized therapies. By miRNA expression profiling of microdissected human tumor biopsy specimens we identified miR-328 as one of the main miRNAs upregulated in invading glioma cells in vivo and further investigated its role in glioma pathogenesis. Methods We employed miRNA mimics and inhibitors to functionally characterize miR-328, 3' untranslated region luciferase assays, and T-cell factor/lymphoid enhancer factor reporter assays to pinpoint miR-328 targets and signaling pathways, and analyzed miR-328 expression in a large panel of gliomas. Results First, we corroborated the invasion-promoting role of miR-328 in A172 and TP365MG glioma cells. Secreted Frizzled-related protein 1 (SFRP1), an inhibitor of Wnt signaling, was then pinpointed as a direct miR-328 target. SFRP1 expression is of prognostic relevance in gliomas with reduced expression, being associated with significantly lower overall patient survival in both the Repository of Molecular Brain Neoplasia Data (REMBRANDT) and The Cancer Genome Atlas. Of note, miR-328 regulated both SFRP1 protein expression levels and Wnt signaling pathway activity. Finally, in human glioma tissues miR-328 appeared to account for the downregulation of SFRP1 preferentially in lower-grade astrocytic gliomas and was inversely related to SFRP1 promoter hypermethylation. Conclusion Taken together, we report on a novel molecular miR-328-dependent mechanism that via SFRP1 inhibition and Wnt activation contributes to the infiltrative glioma phenotype at already early stages of glioma progression, with unfavorable prognostic implications for the final outcome of the disease.

Prognostic or predictive value of MGMT promoter methylation in gliomas depends on IDH1 mutation.

OBJECTIVE: To explore whether the isocitrate dehydrogenase 1 (IDH1) or 1p/19q status determines the prognostic vs predictive role of O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation in the Neuro-Oncology Working Group of the German Cancer Society (NOA)-04 trial anaplastic glioma biomarker cohort. METHODS: Patients (n = 183) of the NOA-04 trial with known MGMT and IDH1 status were analyzed for interdependency of the prognostic vs predictive role of MGMT promoter methylation from IDH1 or 1p/19q status and treatment, using progression-free survival (PFS) as an endpoint. An independent validation cohort of the German Glioma Network (n = 75) and the NOA-08 trial (n = 34) served as a confirmation cohort. RESULTS: In tumors with IDH1 mutation, MGMT promoter methylation was associated with prolonged PFS with chemotherapy ± radiotherapy (RT) or RT-only groups, and is thus prognostic. In tumors without IDH1 mutation, MGMT promoter methylation was associated with increased PFS in patients treated with chemotherapy, but not in those who received RT alone as the first-line treatment, and is thus chemotherapy-predictive. In contrast, 1p/19q codeletions showed no such association with the prognostic vs predictive value of MGMT. CONCLUSIONS: MGMT promoter methylation is a predictive biomarker for benefit from alkylating agent chemotherapy in patients with IDH1-wild-type, but not IDH1-mutant, malignant gliomas of World Health Organization grades III/IV. Combined IDH1/MGMT assessment may help to individualize clinical decision-making in neuro-oncology.

Prognostic significance of molecular markers and extent of resection in primary glioblastoma patients.

PURPOSE: Despite multimodal aggressive treatment glioblastoma patients still face a rather poor prognosis. Recent data indicate that certain molecular markers, in particular MGMT promoter hypermethylation, are associated with response to alkylating chemotherapy and longer survival. The clinical significance of other glioblastoma-associated molecular aberrations and their relationship to MGMT promoter hypermethylation is still poorly understood. EXPERIMENTAL DESIGN: We conducted a translational study involving 67 newly diagnosed glioblastoma patients treated at our institution from 1998 to 2004. All patients were treated by open resection, followed by radiotherapy and adjuvant temozolomide chemotherapy. The tumors were investigated for MGMT promoter methylation, mRNA and protein expression, as well as presence of MGMT sequence polymorphisms. In addition, we screened for genetic aberrations of the EGFR, TP53, CDK4, MDM2, and PDGFRA genes as well as allelic losses on chromosomal arms 1p, 10q, and 19q. RESULTS: Correlation of molecular findings with clinical data revealed significantly longer time to progression after onset of chemotherapy and longer overall survival of patients with MGMT-hypermethylated tumors. In contrast, MGMT protein expression, MGMT polymorphisms, and aberrations in any of the other genes and chromosomes were not significantly linked to patient outcome. Multivariate analysis identified MGMT promoter hypermethylation and near-complete tumor resection as the most important parameters associated with better prognosis. CONCLUSION: Our study provides novel insights into the significance of molecular and clinical markers in predicting the prognosis of glioblastoma patients, which may improve stratification of patients into distinct prognostic subgroups.