O6-Methylguanine-DNA-methyltransferase in recurring anaplastic ependymomas: PCR and immunohistochemistry

Primary spinal anaplastic ependymoma: A single-institute retrospective cohort and systematic review

Objective

Primary spinal anaplastic ependymoma (PSAE) is an extremely rare disease. We aim to report the largest PSAE cohort, evaluate the treatments, and investigate the prognostic factors for progression-free survival (PFS).

Methods

Clinical data collected from the authors' institute and literature articles were pooled and described. Survival analysis and multivariable Cox regression analysis were performed to evaluate therapies and investigate prognostic factors for PFS.

Results

Our cohort included 22 females and 16 males, with a median age of 33 years. PSAE developed mostly on cervical and cervicothoracic levels. The median length measured 3 segments. Half of PSAE were intramedullary. Pain was the most common symptom. The median duration of symptoms was 6 months. Neurological statuses were improved in 76% following treatments, whereas clinical tumor progression occurred in 41.7%. The estimated median progression-free survival was 132 months, and the estimated median survival was 192 months. The median Ki-67 index was 15%. Patients aged less than or equal to 25 experienced worse neurological statuses and more repeated progression. Age less than or equal to 25 (HR 10.312, 95%CI 1.535-69.260, p=0.016), gross total resection (HR 0.116, 95%CI 0.020-0.688, p=0.018), and radiotherapy (HR 0.084, 95%CI 0.009-0.804, p=0.032) are three prognostic factors for tumor progression.

Conclusion

Tumor progression remains a big concern in the clinical course of PSAE. Being aged above 25, undergoing GTR, and accepting adjuvant radiotherapy put patients at lower risk for tumor progression. Younger patients might have worse neurological statuses compared with those aged over 25.

Ependymoma: Evaluation and Management Updates

PURPOSE OF REVIEW

To review state of art and relevant advances in the molecular genetics and management of ependymomas of children and adults.

RECENT FINDINGS

Ependymomas may occur either in the brain or in the spinal cord. Compared with intracranial ependymomas, spinal ependymomas are less frequent and exhibit a better prognosis. The new WHO classification of CNS tumors of 2021 has subdivided ependymomas into different histomolecular subgroups with different outcome. The majority of studies have shown a major impact of extent of resection; thus, a complete resection must be performed, whenever possible, at first surgery or at reoperation. Conformal radiotherapy is recommended for grade 3 or incompletely resected grade II tumors. Proton therapy is increasingly employed especially in children to reduce the risk of neurocognitive and endocrine sequelae. Craniospinal irradiation is reserved for metastatic disease. Chemotherapy is not useful as primary treatment and is commonly employed as salvage treatment for patients failing surgery and radiotherapy. Standard treatments are still the mainstay of treatment: the discovery of new druggable pathways will hopefully increase the therapeutic armamentarium in the near future.

The biology of ependymomas and emerging novel therapies

Ependymomas are rare central nervous system tumours that can arise in the brain's supratentorial region or posterior fossa, or in the spinal cord. In 1924, Percival Bailey published the first comprehensive study of ependymomas. Since then, and especially over the past 10 years, our understanding of ependymomas has grown exponentially. In this Review, we discuss the evolution in knowledge regarding ependymoma subgroups and the resultant clinical implications. We also discuss key oncogenic and tumour suppressor signalling pathways that regulate tumour growth, the role of epigenetic dysregulation in the biology of ependymomas, and the various biological features of ependymoma tumorigenesis, including cell immortalization, stem cell-like properties, the tumour microenvironment and metastasis. We further review the limitations of current therapies such as relapse, radiation-induced cognitive deficits and chemotherapy resistance. Finally, we highlight next-generation therapies that are actively being explored, including tyrosine kinase inhibitors, telomerase inhibitors, anti-angiogenesis agents and immunotherapy.

An Insight into Pathophysiological Features and Therapeutic Advances on Ependymoma

Simple Summary

Although biological information and the molecular classification of ependymoma have been studied, the treatment systems for ependymoma are still insufficient. In addition, because the disease occurs infrequently, it is difficult to obtain sufficient data to conduct large-scale or randomized clinical trials. Therefore, this study is intended to emphasize the importance of understanding its pathological characteristics and prognosis as well as developing treatments for ependymoma through multilateral studies.

Abstract

Glial cells comprise the non-sensory parts of the central nervous system as well as the peripheral nervous system. Glial cells, also known as neuroglia, constitute a significant portion of the mammalian nervous system and can be viewed simply as a matrix of neural cells. Despite being the “Nervenkitt” or “glue of the nerves”, they aptly serve multiple roles, including neuron repair, myelin sheath formation, and cerebrospinal fluid circulation. Ependymal cells are one of four kinds of glial cells that exert distinct functions. Tumorigenesis of a glial cell is termed a glioma, and in the case of an ependymal cell, it is called an ependymoma. Among the various gliomas, an ependymoma in children is one of the more challenging brain tumors to cure. Children are afflicted more severely by ependymal tumors than adults. It has appeared from several surveys that ependymoma comprises approximately six to ten percent of all tumors in children. Presently, the surgical removal of the tumor is considered a standard treatment for ependymomas. It has been conspicuously evident that a combination of irradiation therapy and surgery is much more efficacious in treating ependymomas. The main purpose of this review is to present the importance of both a deep understanding and ongoing research into histopathological features and prognoses of ependymomas to ensure that effective diagnostic methods and treatments can be developed.

A phase II study of dose-dense temozolomide and lapatinib for recurrent low-grade and anaplastic supratentorial, infratentorial, and spinal cord ependymoma

BACKGROUND

No standard medical treatment exists for adult patients with recurrent ependymoma, and prospective clinical trials in this population have not succeeded because of its rarity and challenges in accruing patients. The Collaborative Ependymoma Research Network conducted a prospective phase II clinical trial of dose-dense temozolomide (TMZ) and lapatinib, targeting the unmethylated O6-methylguanine-DNA methyltransferase (MGMT) promoter status and increased expression of ErbB2 (human epidermal growth factor receptor 2) and ErbB1 (epidermal growth factor receptor) in ependymomas.

METHODS

Patients age 18 or older with histologically proven and progressive ependymoma or anaplastic ependymoma were eligible and received dose-dense TMZ and daily lapatinib. The primary outcome measure was median progression-free survival (PFS). Landmark 6- and 12-month PFS and objective response were measured. Serial assessments of symptom burden using the MD Anderson Symptom Inventory Brain Tumor (MDASI-BT)/MDASI-Spine Tumor modules were collected.

RESULTS

The 50 patients enrolled had a median age of 43.5 years, median Karnofsky performance status of 90, and a median of 2 prior relapses. Twenty patients had grade III, 16 grade II, and 8 grade I ependymoma. Half had spinal cord tumors; 15 had a supratentorial tumor, 8 infratentorial, and 2 had disseminated disease. Treatment was well tolerated. The median PFS was 7.8 months (95% CI: 5.5,12.2); the 6- and 12-month PFS rates were 55% and 38%, with 2 complete and 6 partial responses. Measures of symptom burden showed reduction in moderate-severe pain and other disease-related symptoms in most patients.

CONCLUSIONS

This treatment, with demonstrated clinical activity with objective responses and prolonged disease control associated with disease-related symptom improvements, is an option as a salvage regimen for adult patients with recurrent ependymoma.

Abemaciclib, A Selective CDK4/6 Inhibitor, Restricts the Growth of Pediatric Ependymomas

Simple Summary

Pediatric ependymomas are malignant pediatric brain tumors, and one-third of patients exhibit recurrence within two years of initial treatment. Therefore, this study aimed to find new agents to overcome these chemoresistant tumors and defer radiotherapy treatment. By using integrated bioinformatics and experimental validation, we demonstrated that abemaciclib, a CDK4/6 inhibitor, effectively inhibited cell proliferation and induced cell death. Therefore, treatment with abemaciclib showed encouraging results in preclinical pediatric ependymoma models and provide a new therapeutic strategy in the future.

Abstract

Pediatric ependymomas are a type of malignant brain tumor that occurs in children. The overall 10-year survival rate has been reported as being 45–75%. Maximal safe surgical resection combined with adjuvant chemoradiation therapy is associated with the highest overall and progression-free survival rates. Despite aggressive treatment, one-third of ependymomas exhibit recurrence within 2 years of initial treatment. Therefore, this study aimed to find new agents to overcome chemoresistance and defer radiotherapy treatment since, in addition, radiation exposure may cause long-term side effects in the developing brains of young children. By using integrated bioinformatics and through experimental validation, we found that at least one of the genes CCND1 and CDK4 is overexpressed in ependymomas. The use of abemaciclib, a highly selective CDK4/6 inhibitor, effectively inhibited cell proliferation and reduced the expression of cell-cycle-related and DNA-repair-related gene expression via the suppression of RB phosphorylation, which was determined through RNA-seq and Western blot analyses. Furthermore, abemaciclib effectively induced cell death in vitro. The efficiency of abemaciclib was validated in vivo using subcutaneously implanted ependymoma tissues from patient-derived xenografts (PDXs) in mouse models. Treatment with abemaciclib showed encouraging results in preclinical pediatric ependymoma models and represents a potential therapeutic strategy for treating challenging tumors in children.

DNA methylation-based profiling for paediatric CNS tumour diagnosis and treatment: a population-based study

BACKGROUND

Marked variation exists in the use of genomic data in tumour diagnosis, and optimal integration with conventional diagnostic technology remains uncertain despite several studies reporting improved diagnostic accuracy, selection for targeted treatments, and stratification for trials. Our aim was to assess the added value of molecular profiling in routine clinical practice and the impact on conventional and experimental treatments.

METHODS

This population-based study assessed the diagnostic and clinical use of DNA methylation-based profiling in childhood CNS tumours using two large national cohorts in the UK. In the diagnostic cohort-which included routinely diagnosed CNS tumours between Sept 1, 2016, and Sept 1, 2018-we assessed how the methylation profile altered or refined diagnosis in routine clinical practice and estimated how this would affect standard patient management. For the archival cohort of diagnostically difficult cases, we established how many cases could be solved using modern standard pathology, how many could only be solved using the methylation profile, and how many remained unsolvable.

FINDINGS

Of 484 patients younger than 20 years with CNS tumours, 306 had DNA methylation arrays requested by the neuropathologist and were included in the diagnostic cohort. Molecular profiling added a unique contribution to clinical diagnosis in 107 (35%; 95% CI 30-40) of 306 cases in routine diagnostic practice-providing additional molecular subtyping data in 99 cases, amended the final diagnosis in five cases, and making potentially significant predictions in three cases. We estimated that it could change conventional management in 11 (4%; 95% CI 2-6) of 306 patients. Among 195 historically difficult-to-diagnose tumours in the archival cohort, 99 (51%) could be diagnosed using standard methods, with the addition of methylation profiling solving a further 34 (17%) cases. The remaining 62 (32%) cases were unresolved despite specialist pathology and methylation profiling.

INTERPRETATION

Together, these data provide estimates of the impact that could be expected from routine implementation of genomic profiling into clinical practice, and indicate limitations where additional techniques will be required. We conclude that DNA methylation arrays are a useful diagnostic adjunct for childhood CNS tumours.

FUNDING

The Brain Tumour Charity, Children with Cancer UK, Great Ormond Street Hospital Children's Charity, Olivia Hodson Cancer Fund, Cancer Research UK, and the National Institute of Health Research.

EANO guidelines for the diagnosis and treatment of ependymal tumors

Ependymal tumors are rare CNS tumors and may occur at any age, but their proportion among primary brain tumors is highest in children and young adults. Thus, the level of evidence of diagnostic and therapeutic interventions is higher in the pediatric compared with the adult patient population.The diagnosis and disease staging is performed by craniospinal MRI. Tumor classification is achieved by histological and molecular diagnostic assessment of tissue specimens according to the World Health Organization (WHO) classification 2016. Surgery is the crucial initial treatment in both children and adults. In pediatric patients with intracranial ependymomas of WHO grades II or III, surgery is followed by local radiotherapy regardless of residual tumor volume. In adults, radiotherapy is employed in patients with anaplastic ependymoma WHO grade III, and in case of incomplete resection of WHO grade II ependymoma. Chemotherapy alone is reserved for young children <12 months and for adults with recurrent disease when further surgery and irradiation are no longer feasible. A gross total resection is the mainstay of treatment in spinal ependymomas, and radiotherapy is reserved for incompletely resected tumors. Nine subgroups of ependymal tumors across different anatomical compartments (supratentorial, posterior fossa, spinal) and patient ages have been identified with distinct genetic and epigenetic alterations, and with distinct outcomes. These findings may lead to more precise diagnostic and prognostic assessments, molecular subgroup-adapted therapies, and eventually new recommendations pending validation in prospective studies.

Significance of cyclin D1 overexpression in progression and radio-resistance of pediatric ependymomas

Due to the limited efficacy of chemotherapy, the applications of adjuvant irradiation play an important role for ependymoma treatment. However, in the young ages, the resistance of residual and recurrent tumor, and long-term intellectual sequelae remain the major obstacles of radiotherapy. Understanding the mechanism of therapeutic failure caused by radio-resistance is, therefore, crucial in ependymoma treatment. Here we retrospectively analyze clinic-pathological factors in 82 cases of ependymoma less than 20 years old and identify radio-resistant genes through gene expression microarray followed by qRT-PCR validation and immunohistochemistry staining. Thirty-one out of 82 (37.8%) patients are under 3-year-old. The 10 years PFS and OS are 38% and 60%. Gross-total resection is the single significant prognostic factor for longer 10 years PFS and OS in the multivariant analysis (p<0.05). According to the microarray analysis, CCND1 is up-regulated in supratentorial and infratentorial ependymomas and is associated with DNA repair. We demonstrated that 24 primary and 16 recurrent ependymomas were up-regulated, and 5 out of 7 paired samples exhibited higher CCND1 expression in recurrent tumors. We also found RAD51, another DNA repair gene, was up-regulated in supratentorial and infratentorial ependymomas. Knocking down CCND1 reduced cell proliferation and repressed several genes associated with S-phase and DNA repair. Homologous recombination activities of DNA repair were significantly decreased in CCND1-deficient cells while the level of γH2AX was increased after irradiation. In summary, these observations suggest a robust role of CCND1 in regulating cell proliferation and radio-resistance in ependymomas, providing a potential therapeutic target for pediatric ependymomas.

Chemotherapy for intracranial ependymoma in adults

Background

Ependymal tumors in adults are rare, accounting for less than 4 % of primary tumors of the central nervous system in this age group. The low prevalence of intracranial ependymoma in adults limits the ability to perform clinical trials. Therefore, treatment decisions are based on small, mostly retrospective studies and the role of chemotherapy has remained unclear.

Methods

We performed a retrospective study on 17 adult patients diagnosed with intracranial World Health Organisation grade II or III ependymoma, who were treated with chemotherapy at any time during the disease course. Benefit from chemotherapy was estimated by applying Macdonald criteria. Progression-free (PFS) and overall survival (OS) were calculated from start of chemotherapy, using the Kaplan-Meier method.

Results

Eleven patients had supratentorial and 6 infratentorial tumors. Ten patients were treated with temozolomide (TMZ), 3 with procarbazine/lomustine/vincristine (PCV), 3 with platinum-based chemotherapy and 1 patient received epirubicin/ifosfamide. Response rates were as follows: TMZ 8/10 stable disease; PCV 3/3 stable disease; platinum-based chemotherapy 1/3 partial response; epirubicin/ifosfamide 1/1 complete response. PFS rates at 6, 12 and 24 months were 52.9, 35.3 and 23.5 %. OS rates at 6, 12 and 24 months were 82.4, 82.4 and 70.1 %. There was no indication for a favourable prognostic role of O⁶-methylguanyl-DNA-methyltransferase (MGMT) promoter methylation which was detected in 3/12 investigated tumors.

Conclusions

Survival outcomes in response to chemotherapy in adult intracranial ependymoma patients vary substantially, but individual patients may respond to any kind of chemotherapy. There were too few patients to compare survival data between chemotherapeutic subgroups.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2323-0) contains supplementary material, which is available to authorized users.

Biology and management of ependymomas

Ependymomas are rare primary tumors of the central nervous system in children and adults that comprise histologically similar but genetically distinct subgroups. The tumor biology is typically more associated with the site of origin rather than being age-specific. Genetically distinct subgroups have been identified by genomic studies based on locations in classic grade II and III ependymomas. They are supratentorial ependymomas with C11orf95-RELA fusion or YAP1 fusion, infratentorial ependymomas with or without a hypermethylated phenotype (CIMP), and spinal cord ependymomas. Myxopapillary ependymomas and subependymomas have different biology than ependymomas with typical WHO grade II or III histology. Surgery and radiotherapy are the mainstays of treatment, while the role of chemotherapy has not yet been established. An in-depth understanding of tumor biology, developing reliable animal models that accurately reflect tumor molecule features, and high throughput drug screening are essential for developing new therapies. Collaborative efforts between scientists, physicians, and advocacy groups will enhance the translation of laboratory findings into clinical trials. Improvements in disease control underscore the need to incorporate assessment and management of patients' symptoms to ensure that treatment advances translate into improvement in quality of life.

Temozolomide Treatment for Pediatric Refractory Anaplastic Ependymoma with Low MGMT Protein Expression

The benefit of postoperative chemotherapy for anaplastic ependymoma remains unknown. We report two pediatric patients with refractory anaplastic ependymoma treated with temozolomide (TMZ). We did not detect O(6) -methylguanine-DNA methyltransferase (MGMT) promoter methylation in tumor samples; however, MGMT protein expression was low. With TMZ treatment, one patient had a 7-month complete remission; the other, stable disease for 15 months. Three other patients did not respond to TMZ; two had high and one low MGMT expression, and two showed no MGMT promoter methylation. These findings suggest that TMZ may be effective for pediatric refractory anaplastic ependymoma with low MGMT protein expression.

Temozolomide as salvage treatment for recurrent intracranial ependymomas of the adult: a retrospective study

BACKGROUND

Few data are available on temozolomide (TMZ) in ependymomas.We investigated the response, survival, and correlation with MGMT promoter methylation in a cohort of patients with adult intracranial ependymoma receiving TMZ as salvage therapy after failure of surgery and radiotherapy.

PATIENTS AND METHODS

We retrieved clinical information from the institutional database and follow-up visits, and response to TMZ on MRI was evaluated according to the MacDonald criteria.

RESULTS

Eighteen patients (median age, 42 y), with either WHO grade III (10) or grade II (8) ependymoma were evaluable. Tumor location at diagnosis was supratentorial in 11 patients and infratentorial in 7. Progression before TMZ was local in 11 patients, local and spinal in 6 patients, and spinal only in one patient. A median of 8 cycles of TMZ (1-24) was administered. Response to TMZ consisted of complete response (CR) in one (5%) patient, partial response (PR) in 3 (17%) patients, stable disease (SD) in 7 (39%) patients, and progressive disease (PD) in 7 (39%) patients. Maximum response occurred after 3, 10, 14, and 15 cycles, respectively, with neurological improvement in 2 patients. All 4 responding patients were chemotherapy naïve. Both anaplastic (2) and grade II (2) tumors responded. Median progression-free survival and overall survival were 9.69 months (95% CI, 3.22-30.98) and 30.55 months (95% CI, 12.85-52.17), respectively. MGMT methylation was available in 11 patients and was not correlated with response or outcome.

CONCLUSION

TMZ has a role in recurrent chemo-naïve adult patients with intracranial ependymoma, regardless of tumor grade and MGMT methylation. We suggest that, after failure of surgery and radiotherapy, TMZ should be considered as a possible first-line treatment for recurrent ependymoma.

The potential for epigenetic analysis of paediatric CNS tumours to improve diagnosis, treatment and prognosis

Tumours of central nervous system (CNS) origin are the second most prevalent group of cancers in children, yet account for the majority of childhood cancer-related deaths. Such tumours show diverse location, cell type of origin, disease course and long-term outcome, both across and within tumour types, making treatment problematic and contributing to the relatively modest progress in reducing mortality over recent decades. As technological advances begin to reveal the genetic landscape of all cancers, it is becoming increasingly clear that genetic disruption represents only one 'layer' of molecular disruption associated with disease aetiology. Obtaining a full understanding of tumour behaviour requires an understanding of the cellular and molecular pathways disrupted during tumourigenesis, particularly in relation to gene expression. The utility of such an approach has allowed stratification of cancers such as medulloblastoma into subgroups based on molecular features, with potential to refine risk prediction. Given that epigenetic disruption is a universal feature of all human cancers, it is logical to speculate that interrogating epigenetic marks may help to further define the molecular profile, and therefore the clinical trajectory, of tumours. An integrated approach to build a molecular 'signature' of individual tumours that incorporates traditional morphological and demographic information, genetic and transcriptome analysis, in addition to epigenomics (DNA methylation and non-coding RNA analysis), offers tremendous promise to (i) inform treatment approach, (ii) facilitate accurate early identification (preferably at diagnosis) of variable risk groups (both good and poor prognosis groups), and (iii) track disease progression in childhood CNS tumours.

Current treatment options for pediatric and adult patients with ependymoma

OPINION STATEMENT

Survival rates for patients with ependymoma, a glial tumor arising from the ependymal cells lining the ventricles of the brain and spinal cord canal, have changed little during the past decade. Contemporary "standard" therapy for children and adults with ependymoma consists of maximal surgical resection followed by focal irradiation except in cases of disseminated disease. Despite refinements in radiotherapy techniques and improvements in survival for patients with gross totally resected, nonanaplastic disease, many therapeutic challenges remain, especially for patients with unresectable, macroscopic, metastatic, or anaplastic disease. Moreover, radiotherapy to the developing central nervous system, especially in patients younger than age 5 years, can have potential long-term neurocognitive and neuroendocrine sequelae. Chemotherapy has not played a role in most treatment regimens for ependymoma to date, but due to the ongoing therapeutic challenges for a subset of patients, this modality is being reinvestigated in a few ongoing studies. Early recognition of patients who will not respond to primary therapy is imperative to modify treatment regimens, such as intensification with the addition of adjuvant chemotherapy, the use of novel experimental therapies, or their combination. Refinements in patient stratification schemes that are based on a combination of clinical variables and molecular profiles also require improved knowledge of tumor biology. Several molecular alterations have been identified already, some of which may be of prognostic significance. Furthermore, disruption of molecular alterations in signaling pathways involved in the development and maintenance of ependymoma by using novel molecularly targeted therapies may improve outcomes and reduce toxicity for patients with ependymoma.

Genetic expression profiles of adult and pediatric ependymomas: molecular pathways, prognostic indicators, and therapeutic targets

Ependymomas are tumors that can present within either the intracranial or spinal regions. While 90% of all pediatric ependymomas are intracranial, spinal cord ependymomas are more commonly found in patients 20-40 years old. Treatment for spinal lesions has achieved local control rates up to 100% following gross total resection, while pediatric intracranial tumors have 40-60% mortality. Given the inability to effectively treat ependymomas with current standard practices, researchers have focused their efforts on evaluating chromosomal alterations, genetic expression profiles, epigenetic events, and molecular pathways. While these studies have provided critical insight into the potential mechanisms underlying ependymoma pathogenesis, understanding of the intricate interplay between the various pathways involved in tumor initiation, development, and progression will require deeper investigation. However, several potential prognostic markers and therapeutic targets have been identified, providing key areas of focus for future research. The utilization of unique genetic expression profiles based upon patient age, tumor location, tumor grade, and subtype has revealed a multitude of findings warranting further study. Inspection of various molecular pathways associated with ependymomas may establish the foundation for developing novel therapies capable of achieving significant clinical improvements with individualized regimens specifically designed for personalized treatment strategies.

MGMT promoter hypermethylation and its associations with genetic alterations in a series of 350 brain tumors

MGMT (O⁶-methylguanine-DNA methyltransferase) promoter hypermethylation is a helpful prognostic marker for chemotherapy of gliomas, although with some controversy for low-grade tumors. The objective of this study was to retrospectively investigate MGMT promoter hypermethylation status for a series of 350 human brain tumors, including 275 gliomas of different malignancy grade, 21 glioblastoma multiforme (GBM) cell lines, and 75 non-glial tumors. The analysis was performed by methylation-specific PCR and capillary electrophoresis. MGMT expression at the protein level was also evaluated by both immunohistochemistry (IHC) and western blotting analysis. Associations of MGMT hypermethylation with IDH1/IDH2 mutations, EGFR amplification, TP53 mutations, and 1p/19q co-deletion, and the prognostic significance of these, were investigated for the gliomas. MGMT promoter hypermethylation was identified in 37.8% of gliomas, but was not present in non-glial tumors, with the exception of one primitive neuroectodermal tumor (PNET). The frequency was similar for all the astrocytic gliomas, with no correlation with histological grade. Significantly higher values were obtained for oligodendrogliomas. MGMT promoter hypermethylation was significantly associated with IDH1/IDH2 mutations (P = 0.0207) in grade II–III tumors, whereas it had a borderline association with 1p deletion (P = 0.0538) in oligodendrogliomas. No other association was found. Significant correlation of MGMT hypermethylation with MGMT protein expression was identified by IHC in GBMs and oligodendrogliomas (P = 0.0001), but not by western blotting. A positive correlation between MGMT protein expression, as detected by either IHC or western blotting, was also observed. The latter was consistent with MGMT promoter hypermethylation status in GBM cell lines. In low-grade gliomas, MGMT hypermethylation, but not MGMT protein expression, was associated with a trend, only, toward better survival, in contrast with GBMs, for which it had favorable prognostic significance.

O6-Methylguanine-DNA methyltransferase protein expression by immunohistochemistry in brain and non-brain systemic tumours: systematic review and meta-analysis of correlation with methylation-specific polymerase chain reaction

Background

The DNA repair protein O⁶-Methylguanine-DNA methyltransferase (MGMT) confers resistance to alkylating agents. Several methods have been applied to its analysis, with methylation-specific polymerase chain reaction (MSP) the most commonly used for promoter methylation study, while immunohistochemistry (IHC) has become the most frequently used for the detection of MGMT protein expression. Agreement on the best and most reliable technique for evaluating MGMT status remains unsettled. The aim of this study was to perform a systematic review and meta-analysis of the correlation between IHC and MSP.

Methods

A computer-aided search of MEDLINE (1950-October 2009), EBSCO (1966-October 2009) and EMBASE (1974-October 2009) was performed for relevant publications. Studies meeting inclusion criteria were those comparing MGMT protein expression by IHC with MGMT promoter methylation by MSP in the same cohort of patients. Methodological quality was assessed by using the QUADAS and STARD instruments. Previously published guidelines were followed for meta-analysis performance.

Results

Of 254 studies identified as eligible for full-text review, 52 (20.5%) met the inclusion criteria. The review showed that results of MGMT protein expression by IHC are not in close agreement with those obtained with MSP. Moreover, type of tumour (primary brain tumour vs others) was an independent covariate of accuracy estimates in the meta-regression analysis beyond the cut-off value.

Conclusions

Protein expression assessed by IHC alone fails to reflect the promoter methylation status of MGMT. Thus, in attempts at clinical diagnosis the two methods seem to select different groups of patients and should not be used interchangeably.

Molecular diagnostics of gliomas: state of the art

Modern neuropathology serves a key function in the multidisciplinary management of brain tumor patients. Owing to the recent advancements in molecular neurooncology, the neuropathological assessment of brain tumors is no longer restricted to provide information on a tumor's histological type and malignancy grade, but may be complemented by a growing number of molecular tests for clinically relevant tissue-based biomarkers. This article provides an overview and critical appraisal of the types of genetic and epigenetic aberrations that have gained significance in the molecular diagnostics of gliomas, namely deletions of chromosome arms 1p and 19q, promoter hypermethylation of the O6-methylguanine-methyl-transferase (MGMT) gene, and the mutation status of the IDH1 and IDH2 genes. In addition, the frequent oncogenic aberration of BRAF in pilocytic astrocytomas may serve as a novel diagnostic marker and therapeutic target. Finally, this review will summarize recent mechanistic insights into the molecular alterations underlying treatment resistance in malignant gliomas and outline the potential of genome-wide profiling approaches for increasing our repertoire of clinically useful glioma markers.

Ependymomas in adults

Ependymomas are rare primary central nervous system tumors in adults. They occur most commonly in the spinal cord, where histopathologic evaluation is critical to differentiate the grade I myxopapillary ependymoma from the grade II ependymoma or grade III anaplastic ependymoma. Brain ependymomas are either grade II or III. Treatment for all grades and types includes maximum surgical resection. For myxopapillary ependymoma, complete removal while maintaining capsule integrity may be curative. Some grade II ependymomas may be observed carefully after imaging confirms complete resection, but grade III tumors require adjuvant radiation treatment. Radiation commonly is given to the region of tumor, except in cases in which there is imaging or cerebrospinal fluid evidence of tumor dissemination. Chemotherapy has not been studied extensively, although most reports suggest only modest benefit. Ongoing laboratory studies have uncovered important signal transduction pathways that may be better therapeutic targets, leading to the development of clinical trials using targeted agents.

Treatment and outcome of children with relapsed ependymoma: a multi-institutional retrospective analysis

INTRODUCTION

More than a third of children with ependymoma experience relapse, and despite multimodal treatment, less than 25% of them can then achieve long-term survival. Prognostic factors for patients who relapse have not been extensively analyzed.

PATIENTS AND METHODS

We retrospectively analyzed 82 patients from four pediatric oncology European institutions in order to identify prognostic factors and influence of treatment modalities in relapsed ependymoma.

RESULTS

First relapse occurred after a median of 19 months (1 month-16 years). Five-year progression-free survival and overall survival of the cohort were 17% and 27.6%, respectively. Survival was statistically significantly higher for patients achieving gross total resection. No survival benefit was seen for children receiving chemotherapy whereas patients who were amenable to some form of re-irradiation had a better outcome. Objective responses were found in more than 25% of patients receiving oral etoposide, temozolomide, or vincristine/etoposide/cyclophosphamide regimens. Multivariate analysis confirmed that patients with mixed relapses, no surgery at relapse, and receiving chemotherapy did worse (hazard ratio = 3.6, 3.3, and 1.7, respectively, all p < 0.05).

DISCUSSION

Relapsed ependymoma carries a very poor prognosis with an indolent chronic course, leading to death in approximately 90% of the patients. Complete surgical resection whenever possible should be encouraged. Radiation therapy of the relapsed lesions can provide some minor benefit whereas chemotherapy despite the occasional responses provides no benefit in the final outcome which is dismal. Efforts have to be orchestrated internationally to enroll these patients on clinical trials using biology-based therapies.

Management strategies for recurrent ependymoma in the paediatric population

INTRODUCTION

The management of recurrent ependymoma within the paediatric population remains a therapeutic challenge. The options available are varied and patients may have already received prior radio- or chemotherapy. As yet, no consensus exists regarding their optimal treatment. We review the literature and present our contemporary management strategies for this interesting group of patients.

RESULTS AND DISCUSSION

Survival following recurrence is poor and those prognostic factors that predispose to recurrence include extent of surgical resection and the timing of administration of adjuvant therapy. The extent of resection at re-operation can confer a survival advantage, without a necessary increase in morbidity. Strategies aimed at improving surgical resection at first diagnosis include improving and centralising post-surgical radiological review, defining what are true residuals, and centralising surgical review of incompletely resected tumours. Re-irradiation can improve survival, and with the use of conformal radiation fields need not necessarily lead to neuropsychological damage. Cisplatin and etoposide remain the most effective chemotherapeutic agents to date and with an increase in the understanding of tumour biology this may improve further. Because of the complex nature of this group of patients, decisions regarding their management require the involvement of a paediatric neurosurgeon, paediatric neuro-oncologist and paediatric radiation oncologist.

Pediatric ependymoma: biological perspectives

Pediatric ependymomas are enigmatic tumors that continue to present a clinical management challenge despite advances in neurosurgery, neuroimaging techniques, and radiation therapy. Difficulty in predicting tumor behavior from clinical and histological factors has shifted the focus to the molecular and cellular biology of ependymoma in order to identify new correlates of disease outcome and novel therapeutic targets. This article reviews our current understanding of pediatric ependymoma biology and includes a meta-analysis of all comparative genomic hybridization (CGH) studies done on primary ependymomas to date, examining more than 300 tumors. From this meta-analysis and a review of the literature, we show that ependymomas in children exhibit a different genomic profile to those in adults and reinforce the evidence that ependymomas from different locations within the central nervous system (CNS) are distinguishable at a genomic level. Potential biological markers of prognosis in pediatric ependymoma are assessed and the ependymoma cancer stem cell hypothesis is highlighted with respect to tumor resistance and recurrence. We also discuss the shifting paradigm for treatment modalities in ependymoma that target molecular alterations in tumor-initiating cell populations.