Allelic loss of chromosome 1p and radiotherapy plus chemotherapy in patients with oligodendrogliomas

Evaluation of chromosome 1p/19q deletion by Fluorescence in Situ Hybridization (FISH) as prognostic factors in malignant glioma patients on treatment with alkylating chemotherapy

BACKGROUND

Either deletion or co-deletion of chromosomal arms 1p or 19q is a characteristic and early genetic event in oligodendroglial tumors that is associated with a better prognosis and enhanced response to therapy. Information of 1p/19q status is now regarded as the standard of care when managing oligodendroglial tumors for therapeutic options in anticipation of the increased survival and progression-free survival times associated with it. Keeping this in view, we first time attempted to establish the FISH based detection of 1p/19q deletion in glioma tissue samples to evaluate its role and involvement in the disease.

METHOD

Overall 39 glioma cases of different histologies were evaluated by fluorescence in situ hybridization (FISH) technique using specific FISH probes with Olympus BX43 fluorescent microscope to detect chromosomes 1p and 19q or co-deletions therein.

RESULTS

Of the 39 glioma samples, overall 27 (69.2%) were found to have deletion either in 1p, 19q or both. Deletions were observed in 23.0%, 7.6% and 38.4% in 1p, 19q and 1p/19q co-deletions respectively. Overall oligidendrioglioma presented with 53.8% (21 of 39) deletions, astrocytoma group showed 12.8% and GBM accounted for 2.5% deletions. Overall survival and disease free survival was seen significantly better in oligidendrioglioma and astrocytoma with deleted tumors as compared to non-deleted ones (p<0.05).

CONCLUSION

Allelic losses on 1p and 19q, either discretely or shared, were more frequent in classic oligodendrogliomas than in either astrocytoma or Glioblastoma with better survival and response to therapy.

Evaluation of the Oncomine Comprehensive Assay v3 panel for the detection of 1p/19q codeletion in oligodendroglial tumours

AIMS

Accurate assessment of 1p/19q codeletion status in diffuse gliomas is of paramount importance for diagnostic, prognostic and predictive purposes. While targeted next generation sequencing (NGS) has been widely implemented for glioma molecular profiling, its role in detecting structural chromosomal variants is less well established, requiring supplementary informatic tools for robust detection. Herein, we evaluated a commercially available amplicon-based targeted NGS panel (Oncomine Comprehensive Assay v3) for the detection of 1p/19q losses in glioma tissues using an Ion Torrent platform and the standard built-in NGS data analysis pipeline solely.

METHODS

Using as little as 20 ng of DNA from formalin-fixed paraffin-embedded tissues, we analysed 25 previously characterised gliomas for multi-locus copy number losses (CNLs) on 1p and 19q, including 11 oligodendrogliomas (ODG) and 14 non-oligodendroglial (non-ODG) controls. Fluorescence in-situ hybridisation (FISH) was used as a reference standard.

RESULTS

The software confidently detected combined contiguous 1p/19q CNLs in 11/11 ODGs (100% sensitivity), using a copy number cut-off of ≤1.5 and a minimum of 10 amplicons covering the regions. Only partial non-specific losses were identified in non-ODGs (100% specificity). Copy number averages of ODG and non-ODG groups were significantly different (p<0.001). NGS was concordant with FISH and was superior to it in distinguishing partial from contiguous losses indicative of whole-arm chromosomal deletion.

CONCLUSIONS

This commercial NGS panel, along with the standard Ion Torrent algorithm, accurately detected 1p/19q losses in ODG samples, obviating the need for specialised custom-made informatic analyses. This can easily be incorporated into routine glioma workflow as an alternative to FISH.

The Epidemiology of Brain and Spinal Cord Tumors

CNS tumors are a diverse group of neoplasms that emerge from a variety of different CNS cell types. These tumors may be benign, malignant, or borderline in nature. The majority of high grade glial tumors are fatal, with the exception of pilocytic astrocytoma. Primary malignant CNS tumors occur at a global annual rate of 2.1 to 5.8 per 100,000 persons. Males are more likely to develop malignant brain tumors than females, whereas benign meningiomas are more common in adult females. Additionally, gender inequalities in non-malignant tumors peak between the ages of 25 and 29 years. Only a small number of genetic variants have been associated with survival and prognosis. Notably, central nervous system (CNS) tumors exhibit significant age, gender, and race variation. Race is another factor that affects the incidence of brain and spinal cord tumors. Different races exhibit variation in terms of the prevalence of brain and CNS malignancies. This chapter discusses ongoing research on brain and spinal cord tumor epidemiology, as well as the associated risks and accompanied disorders.

Glioblastoma: Prognostic Factors and Predictive Response to Radio and Chemotherapy

Glioblastoma multiforme (GBM) is characterized by poor prognosis despite an aggressive therapeutic strategy. In recent years, many advances have been achieved in the field of glioblastoma biology. Here we try to summarize the main clinical and biological factors impacting clinical prognostication and therapy of GBM patients. From that standpoint, hopefully, in the near future, personalized therapies will be available.

Pattern of disease progression following stereotactic radiosurgery in malignant glioma patients

INTRODUCTION

The clinical benefit of stereotactic radiosurgery (SRS) in the treatment of malignant glioma remains controversial. We analyzed failure patterns of malignant gliomas following SRS to identify the clinical implications of SRS against these malignancies.

MATERIALS AND METHODS

We retrospectively reviewed 58 consecutive patients who received SRS with a gamma knife for their malignant glioma from January 2013 to December 2018. A total of 51 patients were available for analysis of failure patterns. Failure patterns were defined by the recurrent tumors' spatial relation to SRS target as follows: in-field local recurrence, remote recurrence, and leptomeningeal seeding. If patients demonstrated several types of failure patterns simultaneously, we categorized them as a combined failure pattern.

RESULTS

In-field local recurrence was found in 47.1% of patients. Other types of failure patterns were as follows: remote recurrence (19.6%), leptomeningeal seeding (13.7%), and combined failure pattern (19.6%). The majority of patients (52.9%) experienced disease progression beyond the radiation field of SRS, which implies limited efficacy of local therapy against these invasive tumors. The prognosis of patients differed according to failure pattern and patients with local recurrence had better survival outcomes compared to other types of disease progression (p-value = 0.0015, log-rank test).

CONCLUSIONS

This study illustrated that SRS could not improve survival of malignant gliomas significantly even when it had some effect within radiation field. Our findings support utilizing a multidisciplinary treatment strategy to improve the prognosis of malignant gliomas and suggest that SRS is one element of that treatment strategy.

Co-polysomy of 1p/19q in glial tumors: Retrospective analysis of 221 cases from single center

Glial tumors are malignant brain tumors that arise from glial cells of brain or spine and have genetic aberrations in their genome. 1p/19q co-deletion is associated with increased Overall Survival (OS) time with enhanced response to chemo- and radio-therapy in oligodendrogliomas. However, prognostic significance of 1p/19q co-polysomy is still unclear. We evaluated 1p/19q status of 221 patients with glial tumor by Fluorescent in situ Hybridization (FISH). Records of the patients were collected retrospectively. Our results demonstrated that 1p/19q co-polysomy was associated with decreased OS time, high P53 expression and frequently located in temporal lobe, whereas 1p/19q co-deletion was associated with increased overall survival time, low P53 expression and frontal lobe location. Furthermore, classification of patients based on both 1p/19q status and P53 expression revealed that patients with 1p/19q co-polysomy and high P53 expression had the worst prognosis. Lastly, our bioinformatic survival analysis revealed that high expression of SRM, ICMT, and FTL located in 1p36.13-p36.31 and 19q13.2-q13.33 region were related with decreased OS time in patients with Low Grade Glioma (LGG). The study demonstrated that 1p/19q co-polysomy is a poor prognostic marker for glial tumor.

ATRX immunohistochemistry can help refine 'not elsewhere classified' categorisation for grade II/III gliomas

Purpose: The 2016 WHO tumour classification highlights the role of IDH1/2 gene mutation and 1p/19q co-deletion in classifying grade II/III gliomas. A recent cIMPACT-NOW update proposes the use of the term 'Not Elsewhere Classified' (NEC) for IDH-mutant, non co-deleted tumours. Here we show how the incorporation of ATRX immunohistochemistry can be used to better delineate the NEC group. Methods: Clinical data was collected for 112 patients (59% male) treated at our unit. Mutations in IDH1/2 genes were detected by pyrosequencing or immunohistochemistry, 1p/19q co-deletion was assessed with fluorescence in situ hybridisation and ATRX status was determined using immunohistochemical techniques. Tumours were grouped on the basis of molecular markers and outcomes compared. Results: The mean age of diagnosis was 42.6 years (20-73 years). There were 88 oligodendrogliomas (II = 47, III = 41), 18 diffuse astrocytomas (II = 9, III = 9) and 6 oligoastrocytomas (II = 4, III = 2). The majority of gliomas (87.5%) had mutations in IDH1/2. 1p/19q co-deletion was significantly associated with oligodendroglial morphology (p = < 0.001) and was mutually exclusive with ATRX mutation. Classification on the basis of molecular information showed a significant different in survival between the groups. Conclusions: ATRX immunohistochemisty is a useful adjunct which can be used with IDH mutation status, 1p/19q co-deletion and histological findings to further define tumour groups. More work is needed to understand the molecular profiles and prognostic implications for non co-deletion, ATRX preserved cases.

Determination of genetic aberrations and novel transcripts involved in the pathogenesis of oligodendroglioma using array comparative genomic hybridization and next generation sequencing

The aim of the present study was to determine the genetic aberrations and novel transcripts, particularly the fusion transcripts, involved in the pathogenesis of low-grade and anaplastic oligodendroglioma. In the present study, tissue samples were obtained from patients with oligodendroglioma and additionally from archived tissue samples from the Brain Tumor Tissue Bank of the Brain Tumor Foundation of Canada. Six samples were obtained, three of which were low-grade oligodendroglioma and the other three anaplastic oligodendroglioma. DNA and RNA were extracted from each tissue sample. The resulting genomic DNA was then hybridized using the Agilent CytoSure 4×180K oligonucleotide array. Human reference DNA and samples were labeled using Cy3 cytidine 5′-triphosphate (CTP) and Cy5 CTP, respectively, while human Cot-1 DNA was used to reduce non-specific binding. Microarray-based comparative genomic hybridization data was then analyzed for genetic aberrations using the Agilent Cytosure Interpret software v3.4.2. The total RNA isolated from each sample was mixed with oligo dT magnetic beads to enrich for poly(A) mRNA. cDNAs were then synthesized and subjected to end-repair, poly(A) addition and connected using sequencing adapters using the Illumina TruSeq RNA Sample Preparation kit. The fragments were then purified and selected as templates for polymerase chain reaction amplification. The final library was constructed with fragments between 350–450 base pairs and sequenced using deep transcriptome sequencing on an Illumina HiSeq 2500 sequencer. The array comparative genomic hybridization revealed numerous amplifications and deletions on several chromosomes in all samples. However, the most interesting result was from the next generation sequencing, where one anaplastic oligodendroglioma sample was demonstrated to have five novel fusion genes that may potentially serve a critical role in tumor pathogenesis and progression.

Patterns of care and outcomes of postoperative radiation for low-grade gliomas in United States hospitals

It is unclear whether there is a survival benefit with postoperative radiation for low-grade gliomas deemed to be high-risk. We sought to analyze patterns of care and outcomes of radiation use. We accessed the National Cancer Database to identify patients with WHO grade II oligodendroglioma or astrocytoma between 2010 and 2012. Multivariable logistic regression was used to identify predictors of radiation use and multivariable Cox regression was used to identify covariables associated with differences in survival. There were 1952 patients included in this study, of which 518 (26.5%) received postoperative radiation. The majority had oligodendroglioma histology (n = 1121, 57.4%) compared to astrocytoma (n = 831, 42.6%). There were 1626 patients who were either ≥40 years old or underwent a subtotal resection ("high-risk"), and from these 495 (30.4%) received postoperative radiation. On multivariable logistic regression treatment at an academic facility (OR 0.72) was associated with a lower likelihood of receiving postoperative radiation. Astrocytoma histology (OR 2.08), age ≥40 years (OR 2.23), tumor size ≥6 cm (OR 1.64), subtotal resection (OR 1.55), and chemotherapy use (OR 3.93) were associated with an increased likelihood of postoperative radiation. On multivariable analysis, astrocytoma histology (HR 3.49, p < 0.001) and receipt of radiation (HR 2.06, p < 0.001) were associated with worse overall survival. GTR (HR 0.51, p = 0.001) was associated with improved overall survival. Patients treated in United States hospitals are not routinely referred for postoperative radiation for high-risk, low-grade gliomas. Patients who received radiation did not do better than those who did not receive radiation.

Clair WH, Lightner DD, Villano JL. Comprehensive evaluation of treatment and outcomes of low-grade diffuse gliomas

Background

Low-grade gliomas affect younger adults and carry a favorable prognosis. They include a variety of biological features affecting clinical behavior and treatment. Having no guidelines on treatment established, we aim to describe clinical and treatment patterns of low-grade gliomas across the largest cancer database in the United States.

Methods

We analyzed the National Cancer Database from 2004 to 2015, for adult patients with a diagnosis of World Health Organization grade II diffuse glioma.

Results

We analyzed 13,621 cases with median age of 41 years. Over 56% were male, 88.4% were white, 6.1% were black, and 7.6% Hispanic. The most common primary site location was the cerebrum (79.9%). Overall, 72.2% received surgery, 36.0% radiation, and 27.3% chemotherapy. Treatment combinations included surgery only (41.5%), chemotherapy + surgery (6.6%), chemotherapy only (3.1%), radiation + chemotherapy + surgery (10.7%), radiation + surgery (11.5%), radiation only (6.1%), and radiotherapy + chemotherapy (6.7%). Radiation was more common in treatment of elderly patients, 1p/19q co-deletion (37.3% versus 24.3%, p<0.01), and tumors with midline location. Median survival was 11 years with younger age, 1p/19q co-deletion, and cerebrum location offered survival advantage.

Conclusions

Tumor location, 1p/19q co-deletion, and age were the main determinants of treatment received and survival, likely reflecting tumor biology differences. Any form of treatment was preferred over watchful waiting in the majority of the patients (86.1% versus 8.1%). Survival of low-grade gliomas is higher than previously reported in the majority of clinical trials and population-based analyses. Our analysis provides a real world estimation of treatment decisions, use of molecular data, and outcomes.

Non-invasive genotype prediction of chromosome 1p/19q co-deletion by development and validation of an MRI-based radiomics signature in lower-grade gliomas

PURPOSE

To perform radiomics analysis for non-invasively predicting chromosome 1p/19q co-deletion in World Health Organization grade II and III (lower-grade) gliomas.

METHODS

This retrospective study included 277 patients histopathologically diagnosed with lower-grade glioma. Clinical parameters were recorded for each patient. We performed a radiomics analysis by extracting 647 MRI-based features and applied the random forest algorithm to generate a radiomics signature for predicting 1p/19q co-deletion in the training cohort (n = 184). The clinical model consisted of pertinent clinical factors, and was built using a logistic regression algorithm. A combined model, incorporating both the radiomics signature and related clinical factors, was also constructed. The receiver operating characteristics curve was used to evaluate the predictive performance. We further validated the predictability of the three developed models using a time-independent validation cohort (n = 93).

RESULTS

The radiomics signature was constructed as an independent predictor for differentiating 1p/19q co-deletion genotypes, which demonstrated superior performance on both the training and validation cohorts with areas under curve (AUCs) of 0.887 and 0.760, respectively. These results outperformed the clinical model (AUCs of 0.580 and 0.627 on training and validation cohorts). The AUCs of the combined model were 0.885 and 0.753 on training and validation cohorts, respectively, which indicated that clinical factors did not present additional improvement for the prediction.

CONCLUSION

Our study highlighted that an MRI-based radiomics signature can effectively identify the 1p/19q co-deletion in histopathologically diagnosed lower-grade gliomas, thereby offering the potential to facilitate non-invasive molecular subtype prediction of gliomas.

Long-Term Outcome of Postoperative Irradiation in Patients with Newly Diagnosed WHO Grade III Anaplastic Gliomas

Purpose

Patients with anaplastic gliomas have a more favorable overall survival than patients with glioblastomas. In most analyses, WHO grade III and IV tumors are not analyzed separately. The present analysis reports outcome after postoperative radiotherapy in patients with WHO grade III gliomas.

Patients and methods

Between January 1988 and January 2007, 127 patients with WHO grade III tumors were treated with radiotherapy; the histological classification was pure astrocytoma in 104 patients, oligoastrocytoma in 12 and pure oligodendroglioma in 11 patients. Median age was 48 years. After the primary diagnosis, a biopsy had been performed in 72 patients; subtotal and total resections were performed in 37 and 18 patients, respectively. In all patients radiotherapy was applied with a median dose of 60 Gy in conventional fractionation. The median follow-up time was 18 months.

Results

Median overall survival was 17 months. Overall survival was significantly influenced by the extent of surgery. Median overall survival was 32 months after complete resection, 36 months after subtotal resection, and 12 months after biopsy. Median overall survival was 7 months for patients with anaplastic astrocytomas, 44 months for patients with mixed tumors, and 47 months for those with pure oligodendrogliomas. Age significantly influenced overall survival. Median progression-free survival was 9 months; the extent of neurosurgical resection significantly influenced progression-free survival.

Conclusion

Patients with WHO grade III anaplastic astrocytomas, oligodendrogliomas and oligoastrocytomas show favorable overall survival after postoperative radiotherapy compared with glioblastoma patients and should therefore be analyzed separately. Radiochemotherapy might further improve outcome.

Cerebrospinal Fluid (Vascular Endothelial Growth Factor) and Serologic (Recoverin) Tumor Markers for Malignant Glioma

BACKGROUND

Clinically useful tumor markers have yet to be identified for malignant glioma. We report on two potential novel tumor markers, vascular endothelial growth factor (VEGF) and recoverin (protein A). VEGF is a highly specific endothelial cell activator that induces angiogenesis both in vivo and in vitro. Our study was designed to assess whether VEGF could be measured in the cerebrospinal fluid (CSF) of patients with cerebral neoplasms and used as a marker of particular tumors. We also studied serum recoverin levels in patients with various brain tumors and compared these to controls. Recoverin is a detectable serologic protein that is expressed in patients with cancer-associated retinopathy, a paraneoplastic syndrome.

METHODS

In the VEGF arm, we used a solid-phase ELISA to determine the levels of VEGF. CSF samples from patients with anaplastic astrocytoma and glioblastoma multiforme (GBM) and with metastatic and nonastrocytic brain tumors were compared with nontumor control samples. In our recoverin study, an immunoenzymetric assay was used to measure the serum recoverin levels patients with glioma and compared with controls.

RESULTS

In the VEGF arm, 89% of samples with malignant astrocytoma and 27% of nonastrocytoma samples had detectable levels of VEGF. VEGF was not detectable in normal CSF samples. The levels of VEGF were significantly higher in high-grade astrocytomas than in nonastrocytic tumors. Recoverin levels were 10-fold higher in patients with recurrent GBM relative to controls. In patients with low-grade glioma, anaplastic glioma, and GBM with no evidence of recurrence, a 3- to 5-fold increase was observed.

CONCLUSIONS

VEGF is detectable in CSF and may be a potential marker for differentiating astrocytic from nonastrocytic tumors. Recoverin is detectable in serum and may be a useful glioma tumor marker, especially for recurrent active disease. These markers may have application for tumor diagnosis, surveillance, and treatment response.

Clinicopathologic features of small cell glioblastomas

Small cell glioblastoma (SCGBM) is a variant of glioblastomas characterized by a predominant population of small and monomorphic glial cells. The aim of the present study was to investigate clinical, neuroimaging, pathologic, and genetic features of SCGBM. The clinicopathologic and genetic features were evaluated in 14 patients with SCGBM. All cases were divided into multifocal and solitary type by MRI, and extent of microvascular proliferation, intratumoral necrosis, and perivascular lymphocytic accumulation were investigated. IDH1 mutations by immunohistochemistry (IDH1 R132H) and 1p 19q codeletion by fluorescence in situ hybridization were detected. Patients ranged from 23 to 92 years of age (median: 71 years), with three females and eleven males. The overall survival time of the patients ranged from 7 to 23 months (mean: 11 months). Nine patients (64%) were the multifocal type. Pathologic study revealed that the microvascular proliferation, necrosis, and lymphocytic infiltration were limited in SCGBM. Immunohistochemically, tumor cells were negative for IDH1 R132H in all patients. FISH analysis demonstrated that no SCGBM had 1p/19q codeletion in informative patients. Our investigation suggested that an elderly onset and multifocal lesions were characteristics of SCGBM associated with degradation of the immune response, infiltrative feature of tumor cells, and an unfavorable prognosis.

Proposed therapeutic strategy for adult low-grade glioma based on aggressive tumor resection

OBJECT There is no standard therapeutic strategy for low-grade glioma (LGG). The authors hypothesized that adjuvant therapy might not be necessary for LGG cases in which total radiological resection was achieved. Accordingly, they established a treatment strategy based on the extent of resection (EOR) and the MIB-1 index: patients with a high EOR and low MIB-1 index were observed without postoperative treatment, whereas those with a low EOR and/or high MIB-1 index received radiotherapy (RT) and/or chemotherapy. In the present retrospective study, the authors reviewed clinical data on patients with primarily diagnosed LGGs who had been treated according to the above-mentioned strategy, and they validated the treatment policy. Given their results, they will establish a new treatment strategy for LGGs stratified by EOR, histological subtype, and molecular status. METHODS One hundred fifty-three patients with diagnosed LGG who had undergone resection or biopsy at Tokyo Women's Medical University between January 2000 and August 2010 were analyzed. The patients consisted of 84 men and 69 women, all with ages ≥ 15 years. A total of 146 patients underwent surgical removal of the tumor, and 7 patients underwent biopsy. RESULTS Postoperative RT and nitrosourea-based chemotherapy were administered in 48 and 35 patients, respectively. Extent of resection was significantly associated with both overall survival (OS; p = 0.0096) and progression-free survival (PFS; p = 0.0007) in patients with diffuse astrocytoma but not in those with oligodendroglial subtypes. Chemotherapy significantly prolonged PFS, especially in patients with oligodendroglial subtypes (p = 0.0009). Patients with a mutant IDH1 gene had significantly longer OS (p = 0.034). Multivariate analysis did not identify MIB-1 index or RT as prognostic factors, but it did identify chemotherapy as a prognostic factor for PFS and EOR as a prognostic factor for OS and PFS. CONCLUSIONS The findings demonstrated that EOR was significantly correlated with patient survival; thus, one should aim for maximum tumor resection. In addition, patients with a higher EOR can be safely observed without adjuvant therapy. For patients with partial resection, postoperative chemotherapy should be administered for those with oligodendroglial subtypes, and repeat resection should be considered for those with astrocytic tumors. More aggressive treatment with RT and chemotherapy may be required for patients with a poor prognosis, such as those with diffuse astrocytoma, 1p/19q nondeleted tumors, or IDH1 wild-type oligodendroglial tumors with partial resection.

Phase II trial of pre-irradiation and concurrent temozolomide in patients with newly diagnosed anaplastic oligodendrogliomas and mixed anaplastic oligoastrocytomas: long term results of RTOG BR0131

We report on the long-term results of a phase II study of pre-irradiation temozolomide followed by concurrent temozolomide and radiotherapy (RT) in patients with newly diagnosed anaplastic oligodendroglioma (AO) and mixed anaplastic oligoastrocytoma. Pre-RT temozolomide was given for up to 6 cycles. RT with concurrent temozolomide was administered to patients with less than a complete radiographic response. Forty eligible patients were entered and 32 completed protocol treatment. With a median follow-up time of 8.7 years (range 1.1-10.1), median progression-free survival (PFS) is 5.8 years (95 % CI 2.0, NR) and median overall survival (OS) has not been reached (5.9, NR). 1p/19q data are available in 37 cases; 23 tumors had codeletion while 14 tumors had no loss or loss of only 1p or 19q (non-codeleted). In codeleted patients, 9 patients have progressed and 4 have died; neither median PFS nor OS have been reached and two patients who received only pre-RT temozolomide and no RT have remained progression-free for over 7 years. 3-year PFS and 6-year OS are 78 % (95 % CI 61-95 %) and 83 % (95 % CI 67-98 %), respectively. Codeleted patients show a trend towards improved 6-year survival when compared to the codeleted procarbazine/CCNU/vincristrine (PCV) and RT cohort in RTOG 9402 (67 %, 95 % CI 55-79 %). For non-codeleted patients, median PFS and OS are 1.3 and 5.8 years, respectively. These updated results suggest that the regimen of dose intense, pre-RT temozolomide followed by concurrent RT/temozolomide has significant activity, particularly in patients with 1p/19q codeleted AOs and MAOs.

EPMA position paper in cancer: current overview and future perspectives

At present, a radical shift in cancer treatment is occurring in terms of predictive, preventive, and personalized medicine (PPPM). Individual patients will participate in more aspects of their healthcare. During the development of PPPM, many rapid, specific, and sensitive new methods for earlier detection of cancer will result in more efficient management of the patient and hence a better quality of life. Coordination of the various activities among different healthcare professionals in primary, secondary, and tertiary care requires well-defined competencies, implementation of training and educational programs, sharing of data, and harmonized guidelines. In this position paper, the current knowledge to understand cancer predisposition and risk factors, the cellular biology of cancer, predictive markers and treatment outcome, the improvement in technologies in screening and diagnosis, and provision of better drug development solutions are discussed in the context of a better implementation of personalized medicine. Recognition of the major risk factors for cancer initiation is the key for preventive strategies (EPMA J. 4(1):6, 2013). Of interest, cancer predisposing syndromes in particular the monogenic subtypes that lead to cancer progression are well defined and one should focus on implementation strategies to identify individuals at risk to allow preventive measures and early screening/diagnosis. Implementation of such measures is disturbed by improper use of the data, with breach of data protection as one of the risks to be heavily controlled. Population screening requires in depth cost-benefit analysis to justify healthcare costs, and the parameters screened should provide information that allow an actionable and deliverable solution, for better healthcare provision.

Exploitation of adaptive evolution in glioma treatment

Glioblastoma multiforme (GBM) is a malignant neoplasm of the CNS with almost uniform lethality. Even with standard-of-care treatments, the prognosis for patients remains dismal. GBM, as with other malignancies, often acquires treatment resistance after an initial response to therapy. Treatment resistance may come about through the adaptive evolution of tumors in response to selection pressures from treatment interventions and the microenvironment. This review discusses how adaptive evolution might potentially be exploited as a new paradigm in GBM treatment.

The future of high-grade glioma: Where we are and where are we going

High-grade glioma (HGG) are optimally treated with maximum safe surgery, followed by radiotherapy (RT) and/or systemic chemotherapy (CT). Recently, the treatment of newly diagnosed anaplastic glioma (AG) has changed, particularly in patients with 1p19q codeleted tumors. Results of trials currenlty ongoing are likely to determine the best standard of care for patients with noncodeleted AG tumors. Trials in AG illustrate the importance of molecular characterization, which are germane to both prognosis and treatment. In contrast, efforts to improve the current standard of care of newly diagnosed glioblastoma (GB) with, for example, the addition of bevacizumab (BEV), have been largely disappointing and furthermore molecular characterization has not changed therapy except in elderly patients. Novel approaches, such as vaccine-based immunotherapy, for newly diagnosed GB are currently being pursued in multiple clinical trials. Recurrent disease, an event inevitable in nearly all patients with HGG, continues to be a challenge. Both recurrent GB and AG are managed in similar manner and when feasible re-resection is often suggested notwithstanding limited data to suggest benefit from repeat surgery. Occassional patients may be candidates for re-irradiation but again there is a paucity of data to commend this therapy and only a minority of selected patients are eligible for this approach. Consequently systemic therapy continues to be the most often utilized treatment in recurrent HGG. Choice of therapy, however, varies and revolves around re-challenge with temozolomide (TMZ), use of a nitrosourea (most often lomustine; CCNU) or BEV, the most frequently used angiogenic inhibitor. Nevertheless, no clear standard recommendation regarding the prefered agent or combination of agents is avaliable. Prognosis after progression of a HGG remains poor, with an unmet need to improve therapy.

The molecular biology of WHO grade II gliomas

The WHO grading scheme for glial neoplasms assigns Grade II to 5 distinct tumors of astrocytic or oligodendroglial lineage: diffuse astrocytoma, oligodendroglioma, oligoastrocytoma, pleomorphic xanthoastrocytoma, and pilomyxoid astrocytoma. Although commonly referred to collectively as among the "low-grade gliomas," these 5 tumors represent molecularly and clinically unique entities. Each is the subject of active basic research aimed at developing a more complete understanding of its molecular biology, and the pace of such research continues to accelerate. Additionally, because managing and predicting the course of these tumors has historically proven challenging, translational research regarding Grade II gliomas continues in the hopes of identifying novel molecular features that can better inform diagnostic, prognostic, and therapeutic strategies. Unfortunately, the basic and translational literature regarding the molecular biology of WHO Grade II gliomas remains nebulous. The authors' goal for this review was to present a comprehensive discussion of current knowledge regarding the molecular characteristics of these 5 WHO Grade II tumors on the chromosomal, genomic, and epigenomic levels. Additionally, they discuss the emerging evidence suggesting molecular differences between adult and pediatric Grade II gliomas. Finally, they present an overview of current strategies for using molecular data to classify low-grade gliomas into clinically relevant categories based on tumor biology.

Leptomeningeal Disease from Oligodendroglioma: Clinical and Molecular Analysis

Background:

Leptomeningeal disease (LMD) is a late complication of malignant glioma, mostly of glioblastoma, that usually responds poorly to treatment and is rapidly fatal. A long surviving case led us to review our experience with LMD in patients with oligodendrogliomas.

Methods:

A 15-year retrospective chart review was performed. Patients with both oligodendroglial tumors and LMD were identified. A single neuro-pathologist reviewed all histological sections, a single neuro-radiologist reviewed all available images and lp/19q status was assessed.

Results:

Seven out of 145 patients with oligodendroglioma were diagnosed with LMD. Six were male. Median age at tumor diagnosis was 41 years (range, 28-50). None had radiographic or pathological evidence of leptomeningeal or subependymal tumor at initial diagnosis. Most patients had pure anaplastic oligodendrogliomas (4/7); 6/7 had 1p/19q co-deletion. The median time to first relapse was 41 months (range, 19-127). The median time to LMD was 76 months (range, 19-151) from initial diagnosis and 28 months (range, 0-36) from first relapse, respectively. Leptomeningeal disease treatments included spinal radiation and intrathecal and systemic chemotherapy. After progression, some patients with LMD remained stable clinically. The median survival from initial diagnosis was 104 months (range, 19-183) and from LMD diagnosis was 32 months (range, 2-43).

Conclusion:

Leptomeningeal disease is a complication of oligodendroglioma that may occur preferentially in long surviving patients with 1p/19q co-deletion. Leptomeningeal disease in patients with oligodendrogliomas appears to be relatively indolent which may have implications for their treatment and be related to 1p/19q status.

Loss of heterozygosity 1p/19q and survival in glioma: a meta-analysis

BACKGROUND

Glioma is rarely curable, and factors that influence the prognosis of glioma patients are not fully understood. Loss of heterozygosity (LOH) of 1p/19q has long been known to be a typical molecular signature of oligodendroglial neoplasms. However, whether LOH of 1p/19q is associated with survival in gliomas remains controversial. Here our goal was to evaluate the association between LOH of 1p/19q and progression-free survival (PFS) and overall survival (OS) by conducting a meta-analysis among glioma cases.

METHODS

The PubMed and Embase databases were searched from the earliest records to May 2013 to identify studies that met prestated inclusion criteria. Reference lists of retrieved articles were also reviewed. Three authors independently extracted information needed for further analysis. Either a fixed- or a random-effects model was used to calculate the overall combined hazard ratio (HR) estimates.

RESULTS

Twenty-eight eligible studies involving 3 408 cases were included in the meta-analysis. Compared with the chromosomal intact group, codeletion of 1p and 19q was associated with a better PFS (HR = 0.63; 95% CI, 0.52-0.76) and OS (HR = 0.43; 95% CI, 0.35-0.53). Subgroup analyses showed this association to be independent of detection methods and the grades and subtypes of gliomas. Furthermore, isodeletion of chromosome 1p predicted a similar favorable disease outcome (PFS: HR = 0.68; 95% CI, 0.47-0.97) (OS: HR = 0.51; 95% CI, 0.35-0.75), especially in low-grade gliomas, whereas isodeletion of 19q only indicated longer PFS (HR = 0.70; 95% CI, 0.56-0.87).

CONCLUSION

Codeletion of 1p and 19q is associated with better survival rates in glioma. Isodeletion of 1p predicts similar outcomes but to a lesser extent, whereas the effects of isodeletion of 19q remained only marginal.

Short-term survivors in glioblastomas with oligodendroglioma component: a clinical study of 186 Chinese patients from a single institution

This study was designed to display the molecular genetic features of short-term survivors in glioblastomas with oligodendroglioma component (GBMO). A total of 186 patients with histological diagnosis of primary gliomas, including 11 GBMO-STS (short-term survivors, survival ≤12 months), 29 GBMO-LTS (relatively long-term survivors, survival >12 months), 36 anaplastic oligoastrocytoma (AOA) and 110 glioblastoma multiforme (GBM), enrolled in the study. An evaluation form was developed and used to document molecular pathological, clinical and treatment-associated parameters between subgroups. Kaplan–Meier plots for survival showed that the median progression-free survival (PFS) and overall survival (OS) of GBMO-STS were 5.0 and 10.0 months, respectively. Intergroup comparison revealed that the GBMO-STS harbored the most dismal prognosis than those with AOA, GBMO-LTS or GBM (P < 0.001 for PFS, P < 0.001 for OS, respectively). Cox regression analyses revealed that 1p/19q co-deletion and 19p polysomy were independent prognostic factors (P < 0.05). Pearson’s Chi square test demonstrated GBMO-STS exhibited lower 1p/19q co-deletion, IDH1 mutation rates than AOA or GBMO-LTS (P = 0.032, P = 0.045 for 1p/19q co-deletion; P = 0.034, P = 0.005 for IDH1 mutation, respectively) but higher chromosome 1q, 19p polysomy rates compared with AOA or GBM (P = 0.037, P = 0.030 for 1q polysomy; P = 0.017, P = 0.011 for 19p polysomy, respectively). Patients with glioblastomas with oligodendroglioma component concurrent with polysomy for chromosomes 1 and 19 always confers an unfavorable prognosis which needs our extra attention in clinic.

Chemoradiation for anaplastic oligodendrogliomas: clinical outcomes and prognostic value of molecular markers

Combination of procarbazine, lomustine and vincristine (PCV) with radiation therapy (RT) has been associated with longer survival in patients with anaplastic oligodendroglioma (AO) and anaplastic oligoastrocytoma (AOA), especially in those with chromosome 1p/19q codeletion. We report a multicenter retrospective study of 84 consecutive adult patients with AO and AOA treated with RT plus concomitant and adjuvant temozolomide (TMZ) between February 2004 and January 2011. Correlations between chromosome 1p/19q codeletion, isocitrate dehydrogenase1 (IDH1) mutation, and O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation with survival outcomes have been analyzed. For all 84 patients the median overall survival (OS) and progression-free survival rates were 55.6 and 45.2 months, respectively. Grade 3 or 4 hematological toxicity occurred in 17 % of patients. Chromosome 1p/19q codeletion was detected in 57 %, IDH1 mutation in 63 %, and MGMT promoter methylation in 74 % of evaluable patients. In multivariate analysis the presence of chromosome 1p/19q codeletion was associated with significant survival benefit (median OS 34 months in noncodeleted tumors and not reached in codeleted tumors; HR 0.16, 95 % CI 0.03-0.45; P = 0.005). IDH1 mutation was also of prognostic significance for longer survival (P = 0.001; HR 0.20, 95 % 0.06-0.41), whereas MGMT promoter methylation was only of borderline significance. The study indicates that RT with concomitant and adjuvant TMZ is a relatively safe treatment associated with longer survival in patients with 1p/19q codeleted and IDH1 mutated tumors. Results from ongoing randomized studies will be essential to clarify if RT plus TMZ may provide survival as good as or better than RT combined with PCV for patients with AO and AOA.

Primary glioblastoma with oligodendroglial differentiation has better clinical outcome but no difference in common biological markers compared with other types of glioblastoma

BACKGROUND

Glioblastoma multiforme with an oligodendroglial component (GBMO) has been recognized in the World Health Organization classification-however, the diagnostic criteria, molecular biology, and clinical outcome of primary GBMO remain unclear. Our aim was to investigate whether primary GBMO is a distinct clinicopathological subgroup of GBM and to determine the relative frequency of prognostic markers such as loss of heterozygosity (LOH) on 1p and/or 19q, O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation, and isocitrate dehydrogenase 1 (IDH1) mutation.

METHODS

We examined 288 cases of primary GBM and assessed the molecular markers in 57 GBMO and 50 cases of other primary GBM, correlating the data with clinical parameters and outcome.

RESULTS

GBMO comprised 21.5% of our GBM specimens and showed significantly longer survival compared with our other GBM (12 mo vs 5.8 mo, P = .006); there was also a strong correlation with younger age at diagnosis (56.4 y vs 60.6 y, P = .005). Singular LOH of 19q (P = .04) conferred a 1.9-fold increased hazard of shorter survival. There was no difference in the frequencies of 1p or 19q deletion, MGMT promoter methylation, or IDH1 mutation (P = .8, P = 1.0, P = 1.0, respectively).

CONCLUSIONS

Primary GBMO is a subgroup of GBM associated with longer survival and a younger age group but shows no difference in the frequency of LOH of 1p/19q, MGMT, and IDH1 mutation compared with other primary GBM.

The role of MGMT testing in clinical practice: a report of the association for molecular pathology

Recent advances in modern molecular technologies allow for the examination and measurement of cancer-related genomic changes. The number of molecular tests for evaluation of diagnostic, prognostic, or predictive markers is expected to increase. In recent years, O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation has been firmly established as a biomarker in patients diagnosed with gliomas, for both clinical trials and routine clinical management. Similarly, molecular markers, such as loss of heterozygosity (LOH) for 1p/19q have already demonstrated clinical utility in treatment of oligodendroglial tumors, and others might soon show clinical utility. Furthermore, nonrandom associations are being discovered among MGMT, 1p/19q LOH, isocitrate dehydrogenase (IDH) mutations, and other tumor-specific modifications that could possibly enhance our ability to predict outcome and response to therapy. While pathologists are facing new and more complicated requests for clinical genomic testing, clinicians are challenged with increasing numbers of molecular data coming from molecular pathology and genomic medicine. Both pathologists and oncologists need to understand the clinical utility of molecular tests and test results, including issues of turnaround time, and their impact on the application of targeted treatment regimens. This review summarizes the existing data that support the rationale for MGMT promoter methylation testing and possibly other molecular testing in clinically defined glioma subtypes. Various molecular testing platforms for evaluation of MGMT methylation status are also discussed.

How to use molecular markers when caring for a patient with brain cancer: 1P/19Q as a predictive and prognostic marker in the neuro-oncology clinic

Although the central role of 1p/19q codeletion in oligodendroglioma was established almost two decades ago, apart from clear prognostic significance the implications for clinical care have been less clear. This has changed with the long-term follow-up analysis of the EORTC and RTOG trials on procarbazine, lomustine, and vincristine (PCV) chemotherapy in anaplastic oligodendroglioma. These have shown that 1p/19q loss in these tumors is predictive of overall survival benefit of the addition of PCV chemotherapy to radiotherapy.

Molecular predictors of outcome in low-grade glioma

PURPOSE OF REVIEW

Recent and ongoing translational studies in neurooncology have investigated the role of molecular markers as potential predictors of outcome in patients with WHO grade I and II gliomas, commonly summarized as low-grade gliomas (LGGs). Here, we seek to highlight the most relevant molecular aberrations associated with these tumour types and update on recent findings on their potential prognostic and predictive value.

RECENT FINDINGS

So far, no biomarker discussed has any relevance for the postoperative course of disease without genotoxic treatment. Isocitrate dehydrogenase (IDH) mutations, 1p deletion or 1p/19q codeletion have the strongest prognostic impact on survival of patients with LGG, given a genotoxic treatment is provided. Recent findings from phase III clinical trials on anaplastic oligodendroglial tumours conducted in North America and Europe suggest that the addition of procarbazine, lomustine and vincristine to radiotherapy is beneficial in the treatment of anaplastic gliomas with 1p/19q codeletion. To decipher the role of 1p/19q codeletion in LGG will be challenging. Recent developments in v-raf murine sarcoma viral oncogene homolog B1 (BRAF)(V600E)-specific small molecule inhibitors and their clinical approval for other cancer types could turn BRAF(V600E) into a promising molecular predictor of outcome in pilocytic astrocytomas, given a treatment with a mutation-specific BRAF inhibitor is applied.

SUMMARY

Clinical prognostic factors such as age, tumour size and the presence or absence of clinical symptoms have long been recognized in the management of patients with LGGs. Molecular biomarkers are increasingly evolving as additional factors that facilitate diagnostics and therapeutic decision-making. However, further prospective randomized studies including multivariate analyses are needed to clearly distinguish between prognostic and predictive effects.

Distinct IDH1/IDH2 mutation profiles in purely insular versus paralimbic WHO Grade II gliomas

OBJECT

The molecular profile of diffuse WHO Grade II gliomas involving the insular lobe, with a possible impact on outcome, is controversial. The authors undertook this study to investigate a possible difference of molecular patterns between purely insular Grade II gliomas and paralimbic Grade II gliomas that involve both the insular lobe and the frontal and/or temporal structures.

METHODS

From a consecutive series of 47 patients who underwent resection of a Grade II glioma invading the insula, 2 subgroups were identified. The first subgroup included 11 patients with a purely insular tumor. The second subgroup included 36 patients with a paralimbic Grade II glioma also involving the frontal and/or temporal lobe. The authors searched systematically for TP53 mutations, 1p19q codeletion, and IDH1/IDH2 mutations.

RESULTS

There was no significant difference between the 2 subgroups with respect to 1p19q codeletion or TP53 mutations rates. Conversely, IDH1/IDH2 mutations were found in all 11 (100%) of the insular Grade II gliomas but only 20 (55%) of 36 paralimbic Grade II gliomas (p = 0.008). Ten (28%) of the 36 patients in the paralimbic tumor group experienced a malignant transformation, and 6 of them died; whereas neither transformation nor death occurred in the insular tumor group (trend toward significance, p = 0.088).

CONCLUSIONS

These findings demonstrate for the first time distinct IDH1/IDH2 and consequently distinct "triplenegative" patterns in purely insular versus paralimbic Grade II gliomas. Such findings could explain discrepancies reported in the literature, because insular and paralimbic gliomas have not been separated in previous reports. These results may enable physicians to refine the management of Grade II gliomas involving the insula according to the presence or lack of invasion of the frontal and/or temporal areas.

Diagnostic and therapeutic avenues for glioblastoma: no longer a dead end?

Glioblastomas are heterogeneous neoplasms that are driven by complex signalling pathways, and are among the most aggressive and challenging cancers to treat. Despite standard treatment with resection, radiation and chemotherapy, the prognosis of patients with glioblastomas remains poor. An increasing understanding of the molecular pathogenesis of glioblastomas has stimulated the development of novel therapies, including the use of molecular-targeted agents. Identification and validation of diagnostic, prognostic and predictive biomarkers has led to the advancement of clinical trial design, and identification of glioblastoma subgroups with a more-favourable prognosis and response to therapy. In this Review, we discuss common molecular alterations relevant to the biology of glioblastomas, targeted, antiangiogenic and immunotherapies that have impacted on the treatment of this disease, and the challenges and pitfalls associated with these therapies. In addition, we emphasize current biomarkers relevant to the management of patients with glioblastoma.

Enhancing diagnosis, prognosis, and therapeutic outcome prediction of gliomas using genomics

Malignant gliomas are the most frequent type of primary brain tumors. Patients' outcome has not improved despite new therapeutics, thus underscoring the need for a better understanding of their genetics and a fresh approach to treatment. The lack of reproducibility in the classification of many gliomas presents an opportunity where genomics may be paramount for accurate diagnosis and therefore best for therapeutic decisions. The aim of this work is to identify large and focal copy number abnormalities (CNA) and loss of heterozygosity (LOH) events in a malignant glioma population. We hypothesized that these explorations will allow discovery of genetic markers that may improve diagnosis and predict outcome. DNA from glioma specimens were subjected to CNA and LOH analyses. Our studies revealed more than 4000 CNA and several LOH loci. Losses of chromosomes 1p and/or 19q, 10, 13, 14, and 22 and gains of 7, 19, and 20 were found. Several of these alterations correlated significantly with histology and grade. Further, LOH was detected at numerous chromosomes. Interestingly, several of these loci harbor genes with potential or reported tumor suppressor properties. These novel genetic signatures may lead to critical insights into diagnosis, classification, prognosis, and design of individualized therapies.

Clinicopathological features in the recurrence of oligodendroglioma and diffuse astrocytoma

To investigate whether grade II oligodendroglioma was transformed to glioblastoma or not, histopathological evaluation of recurrent oligodendrogliomal tumors (OG) and diffuse astrocytomas (DA) was performed. The OG group was composed of ten patients with OG, including seven oligodendrogliomas and three oligoastrocytomas. The DA group was composed of ten patients with DA, including eight fibrillary astrocytomas and two gemistocytic astrocytomas. The histopathological parameters of glioblastoma including nuclear atypia, multinucleated giant cells, glomeruloid tufts (GT) as a marker of microvascular proliferation, necrosis, and the Ki-67 staining index were investigated. Evaluation of these parameters was scored as follows: 0, none; 1, sporadic; 2, partial; 3, extensive. There were no cases of transformation to glioblastoma in the OG group. There were five cases of transformation to secondary glioblastoma in the DA group. In recurrent tumors, scores of GT and necrosis in the OG group were significantly lower than those in the DA group (p < 0.005). Nuclear atypia and high proliferative activity (Ki-67 index) were identified in recurrent tumors of the OG group. Our study suggested that the extent of GT and necrosis in recurrent OG was less than that in recurrent DA, and transformation to glioblastoma from oligodendroglial tumor was exceptional.

The impact of extent of resection and histological subtype on the outcome of adult patients with high-grade gliomas

OBJECTIVE

We reviewed the relationship between extent of resection and survival of patients with high-grade gliomas with special consideration of an oligodendroglial component.

METHODS

A retrospective review was performed on 160 adult patients with histological diagnosis of high-grade gliomas since 2000. All histological slides were categorized as high-grade astrocytomas or oligodendroglial tumors. Extent of resection was assessed by early post-operative magnetic resonance imaging and classified as complete resection, incomplete resection and biopsy. Measured outcomes were overall survival and progression-free survival. The independent association of extent of resection and survival was analyzed by the multivariate proportional hazard model adjusting for prognostic factors.

RESULTS

The lesions were classified as high-grade astrocytomas in 93 patients and high-grade oligodendroglial tumors in 67 patients. In high-grade astrocytomas, the median survival after complete resection (n = 36), incomplete resection (n = 36) and biopsy (n = 21) was 23.4, 15.3 and 12.6 months, respectively. Complete resection was independently associated with increased overall survival (P < 0.001) and progression-free survival (P = 0.002) compared with incomplete resection, while incomplete resection was not associated with survival benefit compared with biopsy by multivariate analysis. On the other hand, in high-grade oligodendroglial tumors, the majority of patients were still alive and there is no significant difference in the survival between complete resection (n = 24) and incomplete resection (n = 33), while even incomplete resection had a significantly longer overall survival (P < 0.001) and progression-free survival (P = 0.006) compared with biopsy (n = 10).

CONCLUSIONS

Maximal cytoreduction improves the survival of high-grade gliomas, although our data indicated that the impact of extent of resection in high-grade astrocytomas is different from that in high-grade oligodendroglial tumors.

Detection of 1p19q deletion by real-time comparative quantitative PCR

1p/19q (1p and/or 19q) deletions are prognostic factors in oligodendroglial tumors (OT) and predict better survival after both chemotherapy and radiotherapy. While studying 1p/19q status as a potential variable within multivariate prognosis models for OT, we have frequently encountered unknown 1p/19q status within our glioma sample database due to lack of paired blood samples for loss of heterozygosity (LOH) assay and/or failure to perform fluorescence in situ hybridization (FISH). We realized that a 1p and 19q deletion assay that could be reliably performed solely on tumor DNA samples would allow us to fill in these molecular biology data "holes". We built recombinant DNA with fragments of the selected "marker" genes in 1p (E2F2, NOTCH2), and 19q (PLAUR) and "reference" genes (ERC2, SPOCK1, and SPAG16 ) and used it as quantification standard in real-time PCR to gain absolute ratios of marker/reference gene copy numbers in tumor DNA samples, thus called comparative quantitative PCR (CQ-PCR). Using CQ-PCR, we identified 1p and/ or 19q deletions in majority of pure low-grade oligodenroglioma (OG) tumors (17/21, 81%), a large portion of anaplastic oligodendroglioma (AO) tumors (6/15, 47%), but rarely found in mixed oligoastrcytomas (OA) tumors (1/8, 13%). These data are consistent with results of LOH and FISH assays generally reported for these tumor types. In addition, 15 out 18 samples showed concordant results between FISH and CQ-PCR. We conclude that CQ-PCR is a potential means to gain 1p/19q deletion information, which prognostic and predictive values of CQ-PCR-derived 1p/19q status will be determined in a future study.

Molecular biology of brain tumors

Much progress has been made in understanding the molecular genetics of brain tumors, especially gliomas.The development and use of high-throughput platforms that can interrogate molecular lesions on a variety of platforms will increase our ability to identify molecular subclasses of these tumors. Future challenges will include the development of methods to integrate these data among different platforms in order to identify optimal biomarkers and robust subclasses. The ultimate challenge, however, remains the translation of this biological knowledge into improved therapies for patients.

One hundred and one dysembryoplastic neuroepithelial tumors: an adult epilepsy series with immunohistochemical, molecular genetic, and clinical correlations and a review of the literature

Simple and complex forms of dysembryoplastic neuroepithelial tumors (DNTs) are readily recognizable but forms with diffuse growth pattern, and hybrid tumors, that is, mixed DNT and ganglioglioma (DNT/GG), are more contentious entities. Rare DNTs have shown aggressive behavior. We reviewed cortical growth patterns, immunophenotype (including CD34, nestin and calbindin), genetic profile, and outcome in 101 DNT in adults. Simple (n = 18), complex (n = 31), diffuse (n = 35) DNT, and mixed DNT/GG (n = 17) showed no difference in age of onset, associated seizure type, or outcome (67.5% free from seizure; mean follow-up, 6 years). CD34 was seen in 61%, calbindin in 57%, and nestin in 86% of all DNT types; these markers were less common in simple DNT. Peritumoral cortical changes (Layer I hypercellularity [61%], satellite nodules [51.6%]) were frequent, but dyslamination (cortical dysplasia) was not identified. Molecular genetic abnormalities identified in 17 cases were IDH1 mutation (n = 3), 1p/19q loss (n = 10), isolated loss 9q (n = 2), and PTEN loss (n = 3), which were not associated with tumor type or location, higher cell proliferation, or distinguishing clinical features (mean age of epilepsy onset, 9 years; age at surgery = 31 years; 69% free from seizure); none had progression on magnetic resonance imaging (mean follow-up, 6 years). No single feature was predictive of seizure-free outcome, but there was a trend for better outcome in CD34-positive tumors (p = 0.07). One case has shown transformation to a higher grade. This study supports the existence of a range of subtypes of DNT some with overlapping features with ganglioglioma; molecular genetic abnormalities were not predictive of atypical behavior.

Predictive and prognostic factors for gliomas

Despite recent therapeutic advances, gliomas, in particular the most frequent and malignant glioblastoma, remain devastating tumors and need a better molecular characterization to improve both classification and treatment. Currently, three molecular markers, related to better outcome, are particularly useful and complement the histological classification: the 1p/19q codeletion strongly predicts prolonged response to treatment and prolonged survival in oligodendroglial tumors; the O(6)-methylguanine-DNA methyltransferase promoter methylation, which is hypothesized to render the cell more vulnerable to alkylants, is associated with a stronger benefit of concomitant chemoradiotherapy in glioblastomas; mutations of the IDH1 (more rarely IDH2) gene affects 40% of gliomas (but 100% of the 1p/19q codeleted gliomas) and is inversely correlated to grade. IDH1 mutation is a strong and independent predictor of survival, whatever grade considered. The consequences of IDH1/IDH2 mutation (that results in a new enzymatic activity transforming alphacetoglutarate into 2-hydroxyglutarate) are currently under investigation. Recently, integrated genomic, transcriptomic and epigenetic studies have unraveled new glioblastoma subgroups that further refines the molecular classification of these tumors. Such an approach should be extended to lower grade gliomas.

Molecular diagnostics of gliomas

CONTEXT

Gliomas are the most common primary brain tumors of adults and include a variety of histologic types and morphologies. Histologic evaluation remains the gold standard for glioma diagnosis; however, diagnostic difficulty may arise from tumor heterogeneity, overlapping morphologic features, and tumor sampling. Recently, our knowledge about the genetics of these tumors has expanded, and new molecular markers have been developed. Some of these markers have shown diagnostic value, whereas others are useful prognosticators for patient survival and therapeutic response.

OBJECTIVE

To review the most clinically useful molecular markers and their detection techniques in gliomas.

DATA SOURCES

Review of the pertinent literature and personal experience with the molecular testing in gliomas.

CONCLUSIONS

This article provides an overview of the most common molecular markers in neurooncology, including 1p/19q codeletion in oligodendroglial tumors, mutations in the isocitrate dehydrogenase 1 and 2 genes in diffuse gliomas, hypermethylation of the O(6)-methylguanine-DNA methyltransferase gene promoter in glioblastomas and anaplastic gliomas, alterations in the epidermal growth factor receptor and phosphatase and tensin homolog genes in high-grade gliomas, as well as BRAF alterations in pilocytic astrocytomas. Molecular testing of gliomas is increasingly used in routine clinical practice and requires that neuropathologists be familiar with these genetic markers and the molecular diagnostic techniques for their detection.

Molecular markers in low-grade gliomas: predictive or prognostic?

PURPOSE

To investigate whether TP53 mutation, 1p/19q codeletions, O(6)-methylguanylmethyltransferase (MGMT) promoter methylation, and isocitrate dehydrogenase 1 (IDH1) mutation predict natural course of disease or response to radiotherapy or chemotherapy or both in low-grade glioma patients.

EXPERIMENTAL DESIGN

Cohort A consisted of 89 patients with diffuse astrocytoma World Health Organization (WHO) grade II (n = 40), oligoastrocytoma (n = 23), or oligodendroglioma (n = 26) who did not receive radiotherapy or chemotherapy after first operation and were monitored until progression [progressive disease (PD); n = 59] and beyond or until the end of follow-up (n = 30). Cohort B consisted of 50 patients with WHO grade II gliomas who received radiotherapy or chemotherapy at diagnosis. Tumors were analyzed for TP53 mutations, 1p/19q codeletions, MGMT promoter methylation, and IDH1 mutations.

RESULTS

Median progression-free survival (PFS) in cohort A was 4.1 years (95% CI: 3.1-5.1). No molecular marker was prognostic for PFS after surgery alone, using multivariate adjustment for histology, age, and extent of resection. IDH1 mutations were associated with prolonged survival from the diagnosis of PD in oligoastrocytomas (OA II)/oligodendrogliomas (O II) and with overall survival (OS) in all tumors. 1p/19q codeletion and IDH1 mutation were prognostic for PFS and OS in cohort B.

CONCLUSIONS

None of the parameters are sensitive prognostic biomarkers in WHO grade II glioma patients who do not receive radiotherapy or chemotherapy after surgery. Limitations of this study include the selection of patients with favorable outcome, the nonrandomized allocation of treatment, and the insufficient sample size to distinguish between effects of radiotherapy versus chemotherapy. Regardless of histology, IDH1 mutation status is the strongest prognostic marker for OS.

Validation of EORTC prognostic factors for adults with low-grade glioma: a report using intergroup 86-72-51

PURPOSE

A prognostic index for survival was constructed and validated from patient data from two European Organisation for Research and Treatment of Cancer (EORTC) radiation trials for low-grade glioma (LGG). We sought to independently validate this prognostic index with a separate prospectively collected data set (Intergroup 86-72-51).

METHODS AND MATERIALS

Two hundred three patients were treated in a North Central Cancer Treatment Group-led trial that randomized patients with supratentorial LGG to 50.4 or 64.8 Gy. Risk factors from the EORTC prognostic index were analyzed for prognostic value: histology, tumor size, neurologic deficit, age, and tumor crossing the midline. The high-risk group was defined as patients with more than two risk factors. In addition, the Mini Mental Status Examination (MMSE) score, extent of surgical resection, and 1p19q status were also analyzed for prognostic value.

RESULTS

On univariate analysis, the following were statistically significant (p<0.05) detrimental factors for both progression-free survival (PFS) and overall survival (OS): astrocytoma histology, tumor size, and less than total resection. A Mini Mental Status Examination score of more than 26 was a favorable prognostic factor. Multivariate analysis showed that tumor size and MMSE score were significant predictors of OS whereas tumor size, astrocytoma histology, and MMSE score were significant predictors of PFS. Analyzing by the EORTC risk groups, we found that the low-risk group had significantly better median OS (10.8 years vs. 3.9 years, p<0.0001) and PFS (6.2 years vs. 1.9 years, p<0.0001) than the high-risk group. The 1p19q status was available in 66 patients. Co-deletion of 1p19q was a favorable prognostic factor for OS vs. one or no deletion (median OS, 12.6 years vs. 7.2 years; p=0.03).

CONCLUSIONS

Although the low-risk group as defined by EORTC criteria had a superior PFS and OS to the high-risk group, this is primarily because of the influence of histology and tumor size. Co-deletion of 1p19q is a prognostic factor. Future studies are needed to develop a more refined prognostic system that combines clinical prognostic features with more robust molecular and genetic data.

Utility of in situ demonstration of 1p loss and p53 overexpression in pathologic diagnosis of oligodendroglial tumors

To improve the diagnostic accuracy of oligodendroglial tumors and to find more convenient parameters that could predict the cytogenetic status, oligodendroglial and astrocytic tumors were cytogenetically and immunohistochemically investigated. Materials included 22 oligodendroglial tumors (15 oligodendrogliomas and 7 oligoastrocytomas) and 20 astrocytic tumors. 1p loss was examined with the fluorescence in situ hybridization (FISH) method. Expression of GFAP, Olig2 and p53 was immunohistochemically investigated and co-localization of GFAP and Olig2 was evaluated on double-immunostained sections. Furthermore, TP53 mutation analyses were carried out on three oligodendroglial tumors showing p53 protein overexpression with a direct sequence analysis. Our FISH studies demonstrated 1p loss in 73% of oligodendroglial tumors (80% oligodendrogliomas and 57% oligoastrocytomas) and in only 10% of astrocytic tumors. There were no clear-cut morphologic differences between 1p-deleted and 1p-intact oligodendroglial tumors. GFAP and Olig2 were expressed in most oligodendroglial and astrocytic tumors, and their cellular localization was almost independent of each other. Overexpression of p53 was observed in five oligodendroglial tumors, all of which were 1p-intact. In comparison, 16 oligodendroglial tumors with 1p deletion showed no overexpression of p53. TP53 missense mutations were detected in three of the p53 overexpressed oligodendroglial tumors studied. Our results suggest that 1p loss is almost specific to oligodendroglial tumors. Although the prediction of 1p status based solely on the morphologic features seems to be difficult, the immunohistochemistry for p53 is a useful tool in that p53 overexpression is closely related to the 1p-intact status in oligodendroglial tumors.

Leptomeningeal disease in oligodendroglial tumors: a population-based study

In this population-based study, we determined the frequency and clinical characteristics of leptomeningeal disease (LMD) developing in the context of oligodendroglial tumors (oligodendrogliomas and oligoastrocytomas). LMD occurred in only 3.9% (8/204) of oligodendroglial tumors and in patients with more recurrences [mean 2.88 vs. 1.27 in LMD and non-LMD, respectively (p = 0.001)]. In contrast to LMD from systemic solid tumors, the median survival following the diagnosis of LMD in oligodendroglial tumors was surprisingly long at 22 months (95% CI 11–33 months). Treatment with oral chemotherapy seemed as effective as more aggressive treatments (e.g. repeat RT or intrathecal chemotherapy) in these patients.

Risk factors for oligodendroglial tumors: a pooled international study

Oligodendroglial tumors are rare subtypes of brain tumors and are often combined with other glial tumors in epidemiological analyses. However, different demographic associations and clinical characteristics suggest potentially different risk factors. The purpose of this study was to investigate possible risk factors for oligodendroglial tumors (including oligodendroglioma, anaplastic oligodendroglioma, and mixed glioma). Data from 7 case-control studies (5 US and 2 Scandinavian) were pooled. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for age group, gender, and study site. Data on 617 cases and 1260 controls were available for analyses. Using data from all 7 studies, history of allergies and/or asthma was associated with a decreased risk of anaplastic oligodendroglioma (OR = 0.6; 95% CI: 0.4-0.9), and history of asthma only was associated with a decreased risk of oligodendroglioma (OR = 0.5; 95% CI: 0.3-0.9) and anaplastic oligodendroglioma (OR = 0.3; 95% CI: 0.1-0.9). A family history of brain tumors was associated with an increased risk of anaplastic oligodendroglioma (OR = 2.2; 95% CI: 1.1-4.5). Having had chicken pox was associated with a decreased risk of oligodendroglioma (OR = 0.6; 95% CI: 0.4-0.9) and anaplastic oligodendroglioma (OR = 0.5; 95% CI: 0.3-0.9) in the US studies. Although there is some overlap in risk factors between oligodendroglial tumors and gliomas as a group, it is likely that additional factors specific to oligodendroglial tumors have yet to be identified. Large, multi-institution international studies will be necessary to better characterize these etiological risk factors.

The nature and timing of specific copy number changes in the course of molecular progression in diffuse gliomas: further elucidation of their genetic "life story"

Up till now, typing and grading of diffuse gliomas is based on histopathological features. However, more objective tools are needed to improve reliable assessment of their biological behavior. We evaluated 331 diffuse gliomas for copy number changes involving 1p, 19q, CDKN2A, PTEN and EGFR(vIII) by Multiplex Ligation-dependent Probe Amplification (MLPA®, Amsterdam, The Netherlands). Specifically based on the co-occurrence of these aberrations we built a model for the timing of the different events and their exact nature (hemi- → homozygous loss; low-level gain → (high-copy) amplification) in the course of molecular progression. The mutation status of IDH1 and TP53 was also evaluated and shown to correlate with the level of molecular progression. The relevance of the proposed model was confirmed by analysis of 36 sets of gliomas and their 39 recurrence(s) whereas survival analysis for anaplastic gliomas confirmed the actual prognostic relevance of detecting molecular malignancy. Moreover, based on our results, molecular diagnostic analysis of 1p/19q can be further improved as different aberrations were identified, some of them being indicative for advanced molecular malignancy rather than for favorable tumor behavior. In conclusion, identification of molecular malignancy as proposed will aid in establishing a risk profile for individual patients and thereby in therapeutic decision making.