Temozolomide Versus Procarbazine, Lomustine, and Vincristine in Recurrent High-Grade Glioma

Primary brain tumours in adults

Important advances have been made in the understanding and management of adult gliomas and primary CNS lymphomas--the two most common primary brain tumours. Progress in imaging has led to a better analysis of the nature and grade of these tumours. Findings from large phase 3 studies have yielded some standard treatments for gliomas, and have confirmed the prognostic value of specific molecular alterations. High-throughput methods that enable genome-wide analysis of tumours have improved the knowledge of tumour biology, which should lead to a better classification of gliomas and pave the way for so-called targeted therapy trials. Primary CNS lymphomas are a group of rare non-Hodgkin lymphomas. High-dose methotrexate-based regimens increase survival, but the standards of care and the place of whole-brain radiotherapy remain unclear, and are likely to depend on the age of the patient. The focus now is on the development of new polychemotherapy regimens to reduce or defer whole-brain radiotherapy and its delayed complications.

Anaplastic gliomas: radiation, chemotherapy, or both?

The optimal treatment of anaplastic gliomas is controversial. Options for treatment include radiation, chemotherapy or a combination of modalities. This article describes how treatment algorithms for anaplastic gliomas have evolved and interprets the results of recent studies. The available evidence indicates that patients can be treated with either chemotherapy or radiation as initial therapy, with use of the other treatment modality at relapse. Whether subpopulations exist for whom one treatment modality is superior to the other at initial diagnosis must be studied prospectively.

Dose dense 1 week on/1 week off temozolomide in recurrent glioma: a retrospective study

Alternative temozolomide regimens have been proposed to overcome O(6)-methylguanine-DNA methyltransferase mediated resistance. We investigated the efficacy and tolerability of 1 week on/1 week off temozolomide (ddTMZ) regimen in a cohort of patients treated with ddTMZ between 2005 and 2011 for the progression of a glioblastoma during or after chemo-radiation with temozolomide or a recurrence of another type of glioma after radiotherapy and at least one line of chemotherapy. Patients received ddTMZ at 100-150 mg/m(2)/d (days 1-7 and 15-21 in cycles of 28-days). All patients had a contrast enhancing lesion on MRI and the response was assessed by MRI using the RANO criteria; complete and partial responses were considered objective responses. Fifty-three patients were included. The median number of cycles of ddTMZ was 4 (range 1-12). Eight patients discontinued chemotherapy because of toxicity. Two of 24 patients with a progressive glioblastoma had an objective response; progression free survival at 6 months (PFS-6) in glioblastoma was 29%. Three of the 16 patients with a recurrent WHO grade 2 or 3 astrocytoma or oligodendroglioma or oligo-astrocytoma without combined 1p and 19q loss had an objective response and PFS-6 in these patients was 38%. Four out of the 12 evaluable patients with a recurrent WHO grade 2 or 3 oligodendroglioma or oligo-astrocytoma with combined 1p and 19q loss had an objective response; PFS-6 in these patients was 62%. This study indicates that ddTMZ is safe and effective in recurrent glioma, despite previous temozolomide and/or nitrosourea chemotherapy. Our data do not suggest superior efficacy of this schedule as compared to the standard day 1-5 every 4 weeks schedule.

Evolution of care for patients with relapsed glioblastoma

Glioblastoma is the most common and aggressive form of brain tumor in adults and has a poor prognosis and a high recurrence rate despite optimal care. The management of patients with relapsed glioblastoma is challenging, with no widely agreed standard of care. Different chemotherapy and radiotherapy combination treatment strategies provide only modest benefits. Recently, several novel agents, including bevacizumab and XL-184, have demonstrated promising results in Phase II trials with their further evaluation ongoing in Phase III randomized trials. Interpreting the data from such trials is a key challenge in glioblastoma, highlighting the need for relevant and standardized patient assessment techniques. Data from ongoing and planned trials should help to define optimal treatment strategies for this disease.

Towards personalized therapy for patients with glioblastoma

Combined therapy with temozolomide and radiotherapy is a standard treatment and improves the survival for patients with newly diagnosed glioblastoma. However, the prognosis remains poor, with a median survival time of 12-15 months. Currently, several clinical trials of dose-dense temozolomide regimen or molecular-targeting therapies have been performed to overcome the resistance of glioblastoma. In these therapies, rational prognostic biomarkers have also been investigated to predict their outcome and response to treatment. This advanced understanding of the biological markers can help to develop personalized therapies for glioblastoma patients. Generally, due to a reduced tolerance, elderly patients do not seem to benefit from intensive treatment. This population needs individual treatments depended on their age or performance status. In this article, we review the recent studies that can provide personalized therapy for glioblastoma, based on molecular tumor profiling or patients' physical status.

MGMT CpG island is invariably methylated in adult astrocytic and oligodendroglial tumors with IDH1 or IDH2 mutations

We have previously identified a region containing 16 CpGs within the MGMT CpG islands which is critical for the transcriptional control of MGMT (Malley, Acta Neuropathol 2011). To investigate the patterns and incidence of MGMT methylation in astrocytic and oligodendroglial tumors, we quantitatively assessed methylation at these 16 CpGs using bisulfite modification followed by pyrosequencing of 362 gliomas not treated with temozolomide, and correlated the findings with previously identified patterns of genetic abnormalities, patients' age and survival. The MGMT gene was considered to be methylated when the mean methylation of the 16 CpGs was 10% or higher. This cut-off value distinguished diffuse astrocytomas with high and low MGMT expression. Within each tumor type, the patterns of methylation were highly variable and also highly heterogeneous across the 16 CpGs. A high incidence of MGMT methylation was observed in all subtypes of gliomas included in this study. Among a subset of 97 tumors where conventional methylation-specific PCR (MSP) was also applied, methylation was detected by both methods in 54 tumors, while the pyrosequencing results identified a further 17 tumors. No additional cases were found using MSP alone, indicating that pyrosequencing is a robust method for methylation analysis. All tumors with IDH1/IDH2 mutations except two had MGMT methylation, while there were many tumors with MGMT methylation, particularly primary glioblastomas, which had no mutations of IDH1/2. We suggest that MGMT methylation may be one of the earliest events in the development of astrocytic and oligodendroglial tumors.

Recurrent high-grade glioma: a diagnostic and therapeutic challenge

The management of recurrent high-grade gliomas with conventional, as well as targeted, therapies is problematic owing to several confounding issues. First, the diagnosis of recurrence using MRI is not straightforward, making the assessment of images in daily routines, as well as in clinical trials, challenging. While chemotherapies with cytotoxic agents have demonstrated initial treatment response, most tumors recur quickly. Second, targeted therapy itself is confounded by the heterogeneous expression of drug targets and nonlinear signaling effects, with functional redundancy and sidestream feedback mechanisms resulting in treatment failure; however, several active agents have been identified, most notably, bevacizumab (an antibody that sequesters VEGF), cilengitide (an inhibitor of integrin αvβ3/5 signaling) and cediranib (an oral tyrosine kinase inhibitor targeting PDGF receptor, c-Kit and all VEGF receptor subtypes). All of these agents have undergone multiple clinical trials and have demonstrated benefits and progression-free survival prolongation in recurrent disease. Given these advances, it is likely that tailored therapies for tumors harboring specific signaling defects will become more efficient and successful in the management of glioblastoma.

Evolving strategies: future treatment of glioblastoma

Despite recent advances, there remains an unmet need for more effective treatments for newly diagnosed and recurrent glioblastoma (GBM). While currently available alkylator-based and antiangiogenic agents provide some efficacy, novel antiangiogenic and antiglioma treatments that provide enhanced efficacy with improvements in overall survival, the potential to overcome drug resistance and decreased treatment-related toxicity are still needed. Although VEGF-directed angiogenesis is critical during GBM pathogenesis, alternative proangiogenic and glioma-promoting pathways also play a key role in tumor progression. This article reviews the limitations of current GBM treatment, the importance of angiogenic signaling pathways in GBM pathogenesis and the preliminary results of novel antiangiogenic-targeted treatments being evaluated in GBM. Therapies that inhibit multiple glioma signaling pathways, including angiogenesis, have the possibility for further improving outcome in GBM and may represent the best option for increasing overall survival.

Knockdown of stomatin-like protein 2 (STOML2) reduces the invasive ability of glioma cells through inhibition of the NF-κB/MMP-9 pathway

Stomatin-like protein 2 (STOML2), a member of the stomatin family, has been reported to be up-regulated in several types of human cancers. The clinical significance and biological role of STOML2 in gliomas remain largely unknown. Here, we describe the significantly up-regulated expression of STOML2 in glioma cell lines and glioma tissues at both the transcriptional and translational levels. Silencing endogenous STOML2 in glioma cells and primary glioma cells drastically reduced their migratory speed and invasive ability, associated with induction of matrix metallopeptidase 9 (MMP-9). We also demonstrated that knockdown of STOML2 significantly inhibited the transcriptional activity of NF-κB and repressed the expression levels of NF-κB target genes, including MMP-9. A luciferase reporter assay revealed that the impact of STOML2 on MMP-9 expression is NF-κB-dependent. Immunohistochemical analysis showed that the up-regulation of STOML2 was significantly correlated with the WHO histological grade of gliomas (p < 0.001). Patients with higher STOML2 expression levels had an overall shorter survival time, whereas patients with lower expression of STOML2 had a longer survival time. A multivariate analysis revealed that STOML2 expression might be an independent prognostic indicator for the survival of glioma patients. Taken together, our results suggest that overexpression of STOML2 is associated with glioma aggressiveness and may represent an independent prognostic factor for the outcome of glioma patients.

International retrospective study of over 1000 adults with anaplastic oligodendroglial tumors

Treatment for newly diagnosed anaplastic oligodendroglial tumors is controversial. Radiotherapy (RT) alone and in combination with chemotherapy (CT) are the most well studied strategies. However, CT alone is often advocated, especially in cases with 1p19q codeletion. We retrospectively identified 1013 adults diagnosed from 1981-2007 treated initially with RT alone (n = 200), CT + RT (n = 528), CT alone (n = 201), or other strategies (n = 84). Median overall survival (OS) was 6.3 years and time to progression (TTP) was 3.1 years. 1p19q codeletion correlated with longer OS and TTP than no 1p or 19q deletion. In codeleted cases, median TTP was longer following CT + RT (7.2 y) than following CT (3.9 y, P = .003) or RT (2.5 y, P < .001) alone but without improved OS; median TTP was longer following treatment with PCV alone than temozolomide alone (7.6 vs. 3.3 y, P = .019). In cases with no deletion, median TTP was longer following CT + RT (3.1 y) than CT (0.9 y, P = .0124) or RT (1.1 y, P < .0001) alone; OS also favored CT + RT (median 5.0 y) over CT (2.2 y, P = .02) or RT (1.9 y, P < .0001) alone. In codeleted cases, CT alone did not appear to shorten OS in comparison with CT + RT, and PCV appeared to offer longer disease control than temozolomide but without a clear survival advantage. Combined CT + RT led to longer disease control and survival than did CT or RT alone in cases with no 1p19q deletion. Ongoing trials will address these issues prospectively.

Current concepts and management of glioblastoma

Glioblastoma is the most common malignant primary brain tumor in adults. Its often rapid clinical course, with many medical and psychosocial challenges, requires a multidisciplinary management. Modern multimodality treatment and care improve patients' life expectancy and quality of life. This review covers major aspects of care of glioblastoma patients with a focus on the management of common symptoms and complications. We aim to provide a guide for clinicians confronted with glioblastoma patients in their everyday practice.

Salvage therapy with single agent bendamustine for recurrent glioblastoma

The treatment of recurrent glioblastoma (GBM) remains challenging notwithstanding the recent approval of bevacizumab for this indication. Bendamustine has a bifunctional mechanism of action including alkylation, penetrates the CNS and does not show cross resistance to other alkylator chemotherapies. In a single institution phase 2 trial, patients with recurrent GBM were treated with bendamustine (100 mg/m(2)/day administered intravenously for two consecutive days every 4 weeks). The primary study endpoint was 6-month progression free survival (PFS-6). An interim analysis for futility was conducted according to a Simon two-stage minimax design. Complete blood counts were obtained bimonthly, clinical evaluations and brain imaging every month for the first cycle and bimonthly thereafter. Treatment responses were based upon MacDonald criteria. Sixteen patients were enrolled (nine men; seven women), with a median age of 53 years (range 36-68) and a median Karnofsky performance status of 90 (range 70-100). Nine patients were treated at first relapse and seven at second relapse (five patients were bevacizumab failures). A total of 25 cycles of bendamustine were administered with a median of 1 (range 1-6). Bendamustine-related toxicity was seen in eight patients; lymphopenia in seven (5 grade 3; 2 Grade 4), thrombocytopenia in two (1 Grade 3; 1 Grade 4), and neutropenia in one (1 Grade 3). Fourteen patients have died due to disease progression, two patients are alive and on alternative therapies. Only one patient was progression-free at 6 months, triggering the stopping rule for futility. Bendamustine was reasonably well tolerated but failed to meet the study criteria for activity in adults with recurrent GBM.

Combined use of anticancer drugs and an inhibitor of multiple drug resistance-associated protein-1 increases sensitivity and decreases survival of glioblastoma multiforme cells in vitro

Glioblastoma multiforme (GBM) is a brain tumour characterised by a remarkably high chemoresistance and infiltrating capability. To date, chemotherapy with temozolomide has contributed only poorly to improved survival rates in patients. One of the most important mechanisms of chemoresistance comes about through the activity of certain proteins from the ATP-binding cassette superfamily that extrudes antitumour drugs, or their metabolites, from cells. We identify an increased expression of the multiple drug resistance-associated protein 1 (Mrp1) in glioblastoma multiforme biopsies and in T98G and G44 cell lines. The activity of this transporter was also confirmed by measuring the extrusion of the fluorescent substrate CFDA. The sensitivity of GBM cells was low upon exposure to temozolomide, vincristine and etoposide, with decreases in cell viability of below 20% seen at therapeutic concentrations of these drugs. However, combined exposure to vincristine or etoposide with an inhibitor of Mrp1 efficiently decreased cell viability by up to 80%. We conclude that chemosensitization of cells with inhibitors of Mrp1 activity might be an efficient tool for the treatment of human GBM.

A distinct region of the MGMT CpG island critical for transcriptional regulation is preferentially methylated in glioblastoma cells and xenografts

O(6)-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein that removes alkyl DNA adducts such as those induced by alkylating agents. Loss of MGMT expression through transcriptional silencing by hypermethylation of its CpG island (CGI) is found in diverse human cancers including glioblastomas. Glioblastomas that have MGMT methylation respond to temozolomide, an alkylating agent, resulting in improved survival. Consequently, assessment of MGMT methylation has become a therapy response and prognostic indicator. However, it is not clear whether the region of the MGMT CGI commonly analysed is the critical region involved in transcriptional control. We measured methylation levels at each CpG site for the entire MGMT CGI using bisulfite modification and pyrosequencing, and compared them with MGMT mRNA expression in glioblastoma cell lines, xenografts and normal brain tissues (41 samples). Two critical regions were identified (DMR1 and DMR2). DMR2 encompasses the commonly analysed region and was always methylated when DMR1 was methylated. A luciferase reporter assay showed that substitutions of several specific CpG sites within DMR2 significantly attenuated the promoter activity of the MGMT CGI. Our results indicate that several CpG sites within DMR2 play a critical role in the transcriptional control of MGMT, making DMR2 the optimal target for methylation testing. However, given the highly variable patterns of MGMT methylation associated with transcriptional silencing observed in this region among the tumours in this study, methylation levels need to be measured at a number of individual CpGs within DMR2 to confidently predict transcriptional silencing and thus sensitivity to alkylating agents.

Controversies in the adjuvant therapy of high-grade gliomas

The 2-year survival rate of patients with glioblastoma accrued to research studies increased from 10% to nearly 40% from 2000 to 2010. These improvements began with the demonstration of a survival benefit when daily temozolomide was administered with 6 weeks of standard radiation and for 6 months thereafter. This treatment regimen is often associated with significant lymphopenia, thrombocytopenia, and progressive blood-brain barrier dysfunction that can result in clinical and radiologic deterioration without true tumor progression ("pseudoprogression"). With new evidence that combining this cytotoxic agent with radiation improves survival in this malignancy, many investigators have modified the regimen to further improve patient outcomes. These largely uncontrolled studies highlight controversies regarding the optimal therapy of this disease. This review focuses on the following selected controversies: (a) What is the appropriate temozolomide dose, schedule, and duration in the postradiation period? (b) How should other U.S. Food and Drug Administration-approved therapies (such as carmustine wafers and bevacizumab) be incorporated into this treatment regimen? (c) Should the results in glioblastoma be extrapolated to patients aged >70 and to patients with lower grade gliomas? and (d) How should novel therapeutic approaches be added to radiation and temozolomide in clinical trials for patients with newly diagnosed glioblastoma?