Utility of EGFR and PTEN numerical aberrations in the evaluation of diffusely infiltrating astrocytomas. Laboratory investigation

Tissue is the Issue: Biomarkers of Prognosis and Classification in Adult Gliomas

OBJECTIVE

To explain several biomarkers used in primary adult brain tumor diagnosis and the methodologies for their application.

DATA SOURCES

Peer-reviewed literature.

CONCLUSION

In the past few years, several biomarkers have been touted as providing reliable and objective assays of histogenesis, prognosis, and therapeutic sensitivity. A number of these markers have failed the test of time and rigorous practice applications. More recently, assays with diagnostic applications have been reported and validated from multiple laboratories using large numbers of patients in routine clinical practices.

IMPLICATIONS FOR NURSING PRACTICE

This article provides a reference for biomarker tests for gliomas. There is a greater need for nurses to understand the translational interface between basic science and clinical medicine to determine the applications of these biomarkers for the best interests of their patients.

Pathological significance of epidermal growth factor receptor expression and amplification in human gliomas

AIMS

To investigate epidermal growth factor receptor (EGFR) expression and amplification in gliomas and to assess their association with survival.

METHODS AND RESULTS

Immunohistochemistry and fluorescence in-situ hybridization were performed to analyse EGFR status in 158 cases of primary glioma. Kaplan-Meier survival and Cox regression analyses were performed to analyse the prognosis of patients. Overexpression of EGFR and expression of EGFR variant III (EGFRvIII) were found in 102 cases (64.6%) and 47 cases (29.7%), respectively. Overexpression of EGFR was significantly correlated with World Health Organization (WHO) grade and Karnofsky performance score (KPS) (both P < 0.05). Expression of EGFRvIII was significantly correlated with WHO grade, gender, age, and KPS (all P < 0.05). EGFR amplification was found in 46 cases (29.1%), and was significantly correlated with WHO grade, age, KPS and EGFR overexpression (all P < 0.05). Cox multifactor analysis showed that EGFR amplification was an independent unfavourable prognostic factor for human gliomas at all ages, and EGFRvIII was an independent prognostic factor in patients older than 60 years.

CONCLUSION

EGFR amplification and EGFRvIII expression were associated with an unfavourable prognosis for patients of all ages, and for those older than 60 years, respectively. The differing significance of EGFR status in young and old glioma patients and its impact on prognosis needs further study.

Direct inhibition of myosin II effectively blocks glioma invasion in the presence of multiple motogens

Anaplastic gliomas, the most common and malignant of primary brain tumors, frequently contain activating mutations and amplifications in promigratory signal transduction pathways. However, targeting these pathways with individual signal transduction inhibitors does not appreciably reduce tumor invasion, because these pathways are redundant; blockade of any one pathway can be overcome by stimulation of another. This implies that a more effective approach would be to target a component at which these pathways converge. In this study, we have investigated whether the molecular motor myosin II represents such a target by examining glioma invasion in a series of increasingly complex models that are sensitive to platelet-derived growth factor, epidermal growth factor, or both. Our results lead to two conclusions. First, malignant glioma cells are stimulated to invade brain through the activation of multiple signaling cascades not accounted for in simple in vitro assays. Second, even though there is a high degree of redundancy in promigratory signaling cascades in gliomas, blocking tumor invasion by directly targeting myosin II remains effective. Our results thus support our hypothesis that myosin II represents a point of convergence for signal transduction pathways that drive glioma invasion and that its inhibition cannot be overcome by other motility mechanisms.

A sensitive and specific diagnostic panel to distinguish diffuse astrocytoma from astrocytosis: chromosome 7 gain with mutant isocitrate dehydrogenase 1 and p53

One of the major challenges of surgical neuropathology is the distinction of diffuse astrocytoma (World Health Organization grade II) from astrocytosis. The most commonly used ancillary tool to solve this problem is p53 immunohistochemistry (IHC), but this is neither sensitive nor specific. Isocitrate dehydrogenase 1 (IDH1) mutations arecommon in lower-grade gliomas, with most causing a specific amino acid change (R132H) that can be detected with a monoclonal antibody. IDH2 mutations are rare, but they also occur in gliomas. In addition, gains of chromosome 7 are common in gliomas. In this study, we assessed the status of p53, IDH1/2, and chromosome 7 to determine the most useful panel to distinguish astrocytoma from astrocytosis. We studied biopsy specimens from 21 World Health Organization grade II diffuse astrocytomas and 20 reactive conditions. The single most sensitive test to identify astrocytoma is fluorescence in situ hybridization for chromosome 7 gain (76.2%). The combination of p53 and mutant IDH1 IHC provides a higher sensitivity (71.4%) than either test alone (47.8%); this combination offers a practical initial approach for the surgical pathologist. The best overall sensitivity (95%) is achieved when fluorescence in situ hybridization for chromosome 7 gain is added to the p53-mutant IDH1 IHC panel.

Molecular pathology in adult gliomas: diagnostic, prognostic, and predictive markers

Over the past 10 years, there has been an increasing use of molecular markers in the assessment and management of adult malignant gliomas. Some molecular signatures are used diagnostically to help pathologists classify tumours, whereas others are used to estimate prognosis for patients. Most crucial, however, are those markers that are used to predict response to certain therapies, thereby directing clinicians to a particular treatment while avoiding other potentially deleterious therapies. Recently, large-scale genome-wide surveys have been used to identify new biomarkers that have been rapidly developed as diagnostic and prognostic tools. Given these developments, the pace of discovery of new molecular assays will quicken to facilitate personalised medicine in the setting of malignant glioma.