Erik P. Sulman

Identification of a CpG Island Methylator Phenotype that Defines a Distinct Subgroup of Glioma

We have profiled promoter DNA methylation alterations in 272 glioblastoma tumors in the context of The Cancer Genome Atlas (TCGA). We found that a distinct subset of samples displays concerted hypermethylation at a large number of loci, indicating the existence of a glioma-CpG island methylator phenotype (G-CIMP). We validated G-CIMP in a set of non-TCGA glioblastomas and low-grade gliomas. G-CIMP tumors belong to the proneural subgroup, are more prevalent among lower-grade gliomas, display distinct copy-number alterations, and are tightly associated with IDH1 somatic mutations. Patients with G-CIMP tumors are younger at the time of diagnosis and experience significantly improved outcome. These findings identify G-CIMP as a distinct subset of human gliomas on molecular and clinical grounds.

A Randomized Trial of Bevacizumab for Newly Diagnosed Glioblastoma

BACKGROUND Concurrent treatment with temozolomide and radiotherapy followed by maintenance temozolomide is the standard of care for patients with newly diagnosed glioblastoma. Bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor A, is currently approved for recurrent glioblastoma. Whether the addition of bevacizumab would improve survival among patients with newly diagnosed glioblastoma is not known. METHODS In this randomized, double-blind, placebo-controlled trial, we treated adults who had centrally confirmed glioblastoma with radiotherapy (60 Gy) and daily temozolomide. Treatment with bevacizumab or placebo began during week 4 of radiotherapy and was continued for up to 12 cycles of maintenance chemotherapy. At disease progression, the assigned treatment was revealed, and bevacizumab therapy could be initiated or continued. The trial was designed to detect a 25% reduction in the risk of death and a 30% reduction in the risk of progression or death, the two coprimary end points, with the addition of bevacizumab. RESULTS A total of 978 patients were registered, and 637 underwent randomization. There was no significant difference in the duration of overall survival between the bevacizumab group and the placebo group (median, 15.7 and 16.1 months, respectively; hazard ratio for death in the bevacizumab group, 1.13). Progression-free survival was longer in the bevacizumab group (10.7 months vs. 7.3 months; hazard ratio for progression or death, 0.79). There were modest increases in rates of hypertension, thromboembolic events, intestinal perforation, and neutropenia in the bevacizumab group. Over time, an increased symptom burden, a worse quality of life, and a decline in neurocognitive function were more frequent in the bevacizumab group. CONCLUSIONS First-line use of bevacizumab did not improve overall survival in patients with newly diagnosed glioblastoma. Progression-free survival was prolonged but did not reach the prespecified improvement target. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00884741.).

The transcriptional network for mesenchymal transformation of brain tumours

The inference of transcriptional networks that regulate transitions into physiological or pathological cellular states remains a central challenge in systems biology. A mesenchymal phenotype is the hallmark of tumour aggressiveness in human malignant glioma, but the regulatory programs responsible for implementing the associated molecular signature are largely unknown. Here we show that reverse-engineering and an unbiased interrogation of a glioma-specific regulatory network reveal the transcriptional module that activates expression of mesenchymal genes in malignant glioma. Two transcription factors (C/EBPβ and STAT3) emerge as synergistic initiators and master regulators of mesenchymal transformation. Ectopic co-expression of C/EBPβ and STAT3 reprograms neural stem cells along the aberrant mesenchymal lineage, whereas elimination of the two factors in glioma cells leads to collapse of the mesenchymal signature and reduces tumour aggressiveness. In human glioma, expression of C/EBPβ and STAT3 correlates with mesenchymal differentiation and predicts poor clinical outcome. These results show that the activation of a small regulatory module is necessary and sufficient to initiate and maintain an aberrant phenotypic state in cancer cells.

A multigene predictor of outcome in glioblastoma

Only a subset of patients with newly diagnosed glioblastoma (GBM) exhibit a response to standard therapy. To date, a biomarker panel with predictive power to distinguish treatment sensitive from treatment refractory GBM tumors does not exist. An analysis was performed using GBM microarray data from 4 independent data sets. An examination of the genes consistently associated with patient outcome, revealed a consensus 38-gene survival set. Worse outcome was associated with increased expression of genes associated with mesenchymal differentiation and angiogenesis. Application to formalin fixed-paraffin embedded (FFPE) samples using real-time reverse-transcriptase polymerase chain reaction assays resulted in a 9-gene subset which appeared robust in these samples. This 9-gene set was then validated in an additional independent sample set. Multivariate analysis confirmed that the 9-gene set was an independent predictor of outcome after adjusting for clinical factors and methylation of the methyl-guanine methyltransferase promoter. The 9-gene profile was also positively associated with markers of glioma stem-like cells, including CD133 and nestin. In sum, a multigene predictor of outcome in glioblastoma was identified which appears applicable to routinely processed FFPE samples. The profile has potential clinical application both for optimization of therapy in GBM and for the identification of novel therapies targeting tumors refractory to standard therapy.

Epidermal Growth Factor Receptor Variant III Status Defines Clinically Distinct Subtypes of Glioblastoma

PURPOSE The clinical significance of epidermal growth factor receptor variant III (EGFRvIII) expression in glioblastoma multiforme (GBM) and its relationship with other key molecular markers are not clear. We sought to evaluate the clinical significance of GBM subtypes as defined by EGFRvIII status. PATIENTS AND METHODS The expression of EGFRvIII was assessed by immunohistochemistry in 649 patients with newly diagnosed GBM. These data were then examined in conjunction with the expression of phospho-intermediates (in a subset of these patients) of downstream AKT and Ras pathways and YKL-40 as well as with known clinical risk factors, including the Radiation Therapy Oncology Groups recursive partitioning analysis (RTOG-RPA) class. RESULTS The RTOG-RPA class was highly predictive of survival in EGFRvIII-negative patients but much less predictive in EGFRvIII-positive patients. These findings were seen in both an initial test set (n = 268) and a larger validation set (n = 381). Similarly, activation of the AKT/MAPK pathways and YKL-40 positivity were predictive of poor outcome in EGFRvIII-negative patients but not in EGFRvIII-positive patients. Pair-wise combinations of markers identified EGFRvIII and YKL-40 as prognostically important. In particular, outcome in patients with EGFRvIII-negative/YKL-40-negative tumors was significantly better than the outcome in patients with the other three combinations of these two markers. CONCLUSION Established prognostic factors in GBM were not predictive of outcome in the EGFRvIII-positive subset, although this requires confirmation in independent data sets. GBMs negative for both EGFRvIII and YKL-40 show less aggressive behavior.

Phase II Trial of Erlotinib Plus Concurrent Whole-Brain Radiation Therapy for Patients With Brain Metastases From Non–Small-Cell Lung Cancer

PURPOSE Brain metastasis (BM) is a leading cause of death from non-small-cell lung cancer (NSCLC). Reasoning that activation of the epidermal growth factor receptor (EGFR) contributes to radiation resistance, we undertook a phase II trial of the EGFR inhibitor erlotinib with whole-brain radiation therapy (WBRT) in an attempt to extend survival time for patients with BM from NSCLC. Additional end points were radiologic response and safety. PATIENTS AND METHODS Eligible patients had BM from NSCLC, regardless of EGFR status. Erlotinib was given at 150 mg orally once per day for 1 week, then concurrently with WBRT (2.5 Gy per day 5 days per week, to 35 Gy), followed by maintenance. EGFR mutation status was tested by DNA sequencing at an accredited core facility. RESULTS Forty patients were enrolled and completed erlotinib plus WBRT (median age, 59 years; median diagnosis-specific graded prognostic assessment score, 1.5). The overall response rate was 86% (n = 36). No increase in neurotoxicity was detected, and no patient experienced grade ≥ 4 toxicity, but three patients required dose reduction for grade 3 rash. At a median follow-up of 28.5 months (for living patients), median survival time was 11.8 months (95% CI, 7.4 to 19.1 months). Of 17 patients with known EGFR status, median survival time was 9.3 months for those with wild-type EGFR and 19.1 months for those with EGFR mutations. CONCLUSION Erlotinib was well tolerated in combination with WBRT, with a favorable objective response rate. The higher-than-expected rate of EGFR mutations in these unselected patients raises the possibility that EGFR-mutated tumors are prone to brain dissemination.

MGMT promoter methylation is predictive of response to radiotherapy and prognostic in the absence of adjuvant alkylating chemotherapy for glioblastoma

Hypermethylation of the O(6)-methylguanine-DNA-methyltransferase (MGMT) gene has been shown to be associated with improved outcome in glioblastoma (GBM) and may be a predictive marker of sensitivity to alkylating agents. However, the predictive utility of this marker has not been rigorously tested with regard to sensitivity to other therapies, namely radiation. To address this issue, we assessed MGMT methylation status in a cohort of patients with GBM who underwent radiation treatment but did not receive chemotherapy as a component of adjuvant treatment. Formalin-fixed, paraffin-embedded tumor samples from 225 patients with newly diagnosed GBM were analyzed via methylation-specific, quantitative real-time polymerase chain reaction following bisulfite treatment on isolated DNA to assess MGMT promoter methylation status. In patients who received radiotherapy alone following resection, methylation of the MGMT promoter correlated with an improved response to radiotherapy. Unmethylated tumors were twice as likely to progress during radiation treatment. The median time interval between resection and tumor progression of unmethylated tumors was also nearly half that of methylated tumors. Promoter methylation was also found to confer improved overall survival in patients who did not receive adjuvant alkylating chemotherapy. Multivariable analysis demonstrated that methylation status was independent of age, Karnofsky performance score, and extent of resection as a predictor of time to progression and overall survival. Our data suggest that MGMT promoter methylation appears to be a predictive biomarker of radiation response. Since this biomarker has also been shown to predict response to alkylating agents, perhaps MGMT promoter methylation represents a general, favorable prognostic factor in GBM.

The transcriptional coactivator TAZ regulates mesenchymal differentiation in malignant glioma

Recent molecular classification of glioblastoma (GBM) has shown that patients with a mesenchymal (MES) gene expression signature exhibit poor overall survival and treatment resistance. Using regulatory network analysis of available expression microarray data sets of GBM, including The Cancer Genome Atlas (TCGA), we identified the transcriptional coactivator with PDZ-binding motif (TAZ), to be highly associated with the MES network. TAZ expression was lower in proneural (PN) GBMs and lower-grade gliomas, which correlated with CpG island hypermethylation of the TAZ promoter compared with MES GBMs. Silencing of TAZ in MES glioma stem cells (GSCs) decreased expression of MES markers, invasion, self-renewal, and tumor formation. Conversely, overexpression of TAZ in PN GSCs as well as murine neural stem cells (NSCs) induced MES marker expression and aberrant osteoblastic and chondrocytic differentiation in a TEAD-dependent fashion. Using chromatin immunoprecipitation (ChIP), we show that TAZ is directly recruited to a majority of MES gene promoters in a complex with TEAD2. The coexpression of TAZ, but not a mutated form of TAZ that lacks TEAD binding, with platelet-derived growth factor-B (PDGF-B) resulted in high-grade tumors with MES features in a murine model of glioma. Our studies uncover a direct role for TAZ and TEAD in driving the MES differentiation of malignant glioma.

IMRT Reirradiation of Head and Neck Cancer-Disease Control and Morbidity Outcomes

PURPOSE Institutional and cooperative group experience has demonstrated the feasibility of reirradiation for head and neck cancer. Limited data are available regarding the use of intensity-modulated radiotherapy (IMRT) for this indication. We reviewed our initial experience using IMRT for previously irradiated head and neck cancer patients. METHODS AND MATERIALS Records of 78 consecutive patients reirradiated with IMRT for head and neck cancer between 1999 and 2004 were reviewed; 74 cases were analyzed. Reirradiation was defined as any overlap between original and new radiation treatment volumes regardless of the time interval between initial and subsequent treatment. Severe reirradiation-related toxicity was defined as toxic events resulting in hospitalization, corrective surgery, or patient death. Longitudinal estimates of survival were calculated by Kaplan-Meier technique. RESULTS Twenty (27%) patients underwent salvage surgical resection and 36 (49%) patients received chemotherapy. Median follow-up from reirradiation was 25 months. Median time interval between initial radiation and reirradiation was 46 months. Median reirradiation dose was 60 Gy. Median lifetime radiation dose was 116.1 Gy. The 2-year overall survival and locoregional control rates were 58% and 64%, respectively. Severe reirradiation related toxicity occurred in 15 patients (20%); one treatment-related death was observed. CONCLUSIONS The use of IMRT for reirradiation of recurrent or second primary head and neck cancers resulted in encouraging local control and survival. Reirradiation-related morbidity was significant, but may be less severe than previously published reports using conventional techniques.

IDH1 mutant malignant astrocytomas are more amenable to surgical resection and have a survival benefit associated with maximal surgical resection

BACKGROUND IDH1 gene mutations identify gliomas with a distinct molecular evolutionary origin. We sought to determine the impact of surgical resection on survival after controlling for IDH1 status in malignant astrocytomas-World Health Organization grade III anaplastic astrocytomas and grade IV glioblastoma. METHODS Clinical parameters including volumetric assessment of preoperative and postoperative MRI were recorded prospectively on 335 malignant astrocytoma patients: n = 128 anaplastic astrocytomas and n = 207 glioblastoma. IDH1 status was assessed by sequencing and immunohistochemistry. RESULTS IDH1 mutation was independently associated with complete resection of enhancing disease (93% complete resections among mutants vs 67% among wild-type, P < .001), indicating IDH1 mutant gliomas were more amenable to resection. The impact of residual tumor on survival differed between IDH1 wild-type and mutant tumors. Complete resection of enhancing disease among IDH1 wild-type tumors was associated with a median survival of 19.6 months versus 10.7 months for incomplete resection; however, no survival benefit was observed in association with further resection of nonenhancing disease (minimization of total tumor volume). In contrast, IDH1 mutants displayed an additional survival benefit associated with maximal resection of total tumor volume (median survival 9.75 y for >5 cc residual vs not reached for <5 cc, P = .025). CONCLUSIONS The survival benefit associated with surgical resection differs based on IDH1 genotype in malignant astrocytic gliomas. Therapeutic benefit from maximal surgical resection, including both enhancing and nonenhancing tumor, may contribute to the better prognosis observed in the IDH1 mutant subgroup. Thus, individualized surgical strategies for malignant astrocytoma may be considered based on IDH1 status.