Concordance analysis and diagnostic test accuracy review of IDH1 immunohistochemistry in glioblastoma

Molecular Biomarker Testing for the Diagnosis of Diffuse Gliomas

CONTEXT.—

The diagnosis and clinical management of patients with diffuse gliomas (DGs) have evolved rapidly over the past decade with the emergence of molecular biomarkers that are used to classify, stratify risk, and predict treatment response for optimal clinical care.

OBJECTIVE.—

To develop evidence-based recommendations for informing molecular biomarker testing for pediatric and adult patients with DGs and provide guidance for appropriate laboratory test and biomarker selection for optimal diagnosis, risk stratification, and prediction.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. A systematic review of literature was conducted to address the overarching question, "What ancillary tests are needed to classify DGs and sufficiently inform the clinical management of patients?" Recommendations were derived from quality of evidence, open comment feedback, and expert panel consensus.

RESULTS.—

Thirteen recommendations and 3 good practice statements were established to guide pathologists and treating physicians on the most appropriate methods and molecular biomarkers to include in laboratory testing to inform clinical management of patients with DGs.

CONCLUSIONS.—

Evidence-based incorporation of laboratory results from molecular biomarker testing into integrated diagnoses of DGs provides reproducible and clinically meaningful information for patient management.

Immunohistochemical Detection and Prognostic Significance of p53, Epidermal Growth Factor Receptor, Murine Double Minute 2, and Isocitrate Dehydrogenase 1 in Glioblastoma Multiforme Patients of Pakistan

Introduction:

Glioblastoma multiforme (GBM) is one of the deadliest cranial tumors occurring in adults. Various biomarkers have been tested for their significance in diagnosis, prognosis, and treatment of GBM. Some well-studied markers in GBM are Isocitrate dehydrogenase 1 (IDH1), Murine double minute 2 (MDM2), Epidermal Growth Factor Receptor (EGFR), and p53. The aim of this study was to investigate the protein expression of these markers in GBM patients of Pakistan.

Methods:

A total of 102 surgically resected formalin-fixed paraffin-embedded specimens from patients diagnosed and treated at Aga Khan University Hospital were included in this study. Immunohistochemistry (IHC) for IDH1, MDM2, EGFR, and p53 was performed using Dako EnVision System and respective monoclonal antibodies. Survival analysis was performed to check association of markers protein expression with prognosis in GBM patients.

Results:

There were 73 males and 29 females in this study, with a median age of 49 years at the time diagnosis. Overexpression of molecular markers was as follows: 52% for EGFR, 26% for p53, 72% for IDH1, and 83% for MDM2. We did observe that EGFR was significantly associated with increased age of our patients and with worse survival. Age > 40 years was a predictor for worse prognosis as well.

Conclusion:

EGFR overexpression and advanced age were worse prognostic indicators.

Immunohistochemical characterisation and histopathology of astrocytic neoplasms at a tertiary Nigerian hospital

AIM

To describe histological features and pattern of expression of selected markers including epithelial growth factor receptor (EGFR), mutant p53 and mutant isocitrate dehydrogenase-1 (IDH-1R132H) among astrocytic neoplasms at the University College Hospital, Ibadan, Nigeria.

DESIGN

A retrospective cross-sectional study involving histologically diagnosed Central Nervous System (CNS) neoplasms between January 2004 and December 2015. Haematoxylin and Eosin Slides of 81 cases of astrocytomas were retrieved, re-cut and reviewed. Ethical clearance was obtained from the ethical board of the hospital. Immunohistochemistry using the Biotin-Streptavidin system was performed with IDH-1 R132H, p53 and EGFR mouse monoclonal antibodies (MOABs) specific against all the cases of astrocytomas under review. All cases were graded and classified using the World Health Organisation (WHO) Classification of Central Nervous System tumours (2016). Membranous and cytoplasmic staining of EGFR and IDH-1R132H mouse monoclonal antibodies, respectively, were regarded as positive while nuclear staining of p53 mouse monoclonal antibody was regarded as positive. The data obtained were analysed with the level of statistical significance set at P < .05.

RESULTS

Males constituted a majority of cases, 50 (61.7%). Male-Female ratio was 1.6:1. Mean age was 30.6 years. Tumours were of a higher WHO grade with increasing age, albeit glioblastoma cases tended to present at younger ages. The higher WHO grades were more likely to be located supratentorially. Glioblastomas accounted for most of the diagnosis 39 (48.1%), followed by pilocytic astrocytomas at 23 (28.4%). There was a low positive cytoplasmic expression of IDH-1 with only three (3.7%) being positive, eight (9.9%) showed a positive nuclear expression for mutant p53 while 17 (21%) showed membranous positivity for EGFR expression.

CONCLUSION

There are similar epidemiological trends between our cohort of patients and as described in most instances worldwide. Optimal stratification for astrocytomas can be achieved using a combination of IDH-1/EGFR immunohistochemistry.

Comparison of Polymerase Chain Reaction-Restriction Fragment Length Polymorphism, Immunohistochemistry, and DNA Sequencing for the Detection of IDH1 Mutations in Gliomas

BACKGROUND

IDH1 mutation shows diagnostic, prognostic, and predictive value in gliomas. Direct Sanger sequencing is considered the gold standard to detect IDH1 mutation. However, this technology is not available in most neuropathological centers in developing countries such as Indonesia. Immunohistochemistry (IHC) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) have also been used to detect IDH1 mutation. This study aimed to compare DNA sequencing, IHC, and PCR-RFLP in detecting IDH1 mutations in gliomas.

METHODS

Research subjects were recruited from Dr. Sardjito Hospital. Genomic DNA was extracted from fresh or formalin-fixed paraffin-embedded samples of tumor tissue. DNA sequencing, PCR-RFLP and IHC were performed to detect IDH1 mutation. Sensitivity, specificity, and accuracy of PCR-RFLP and IHC were calculated by comparing them to DNA sequencing as the gold standard.

RESULTS

Among 61 recruited patients, 13 (21.3%) of them carried a mutation in codon 132 of the IDH1 gene, as shown by DNA sequencing. PCR-RFLP and DNA sequencing have a concordance value of 100%. Meanwhile, the concordance value between IDH1 R132H IHC and DNA sequencing was 96.7%. The sensitivity, specificity, positive predictive values, negative predictive values, and accuracy for PCR-RFLP were all 100%. On the other hand, the sensitivity, specificity, and accuracy of IHC were 92.3%, 97.9%, and 96.7%, respectively.

CONCLUSION

This study showed that both PCR-RFLP and IHC have high accuracy in detecting IDH1 mutation. We recommend a combination of PCR-RFLP and IHC to detect IDH1 mutation in resource-limited settings.<br />.

Gene Expression Profiling of Chemokines and Their Receptors in Low and High Grade Astrocytoma

Background: Despite intense interest in molecular characterization and searches for novel therapeutic targets, the glioblastoma remains a formidable clinical challenge. Among many contributors to gliomagenesis, chemokines have drawn special attention due to their involvement in a plethora of biological processes and pathological conditions. In the present study we aimed to elucidate any pro-gliomagenic chemokine axis and probable roles in development of glioblastoma multiforme (GBM). Method: An array of 84 chemokines, chemokine receptors and related genes were studied by real time PCR with comparison between low grade astrocytoma (diffuse astrocytoma – grade II) and high grade astrocytoma (glioblastoma multiforme – grade IV). Gene ontology analysis and database mining were performed to funnel down the important axis in GBM followed by validation at the protein level by immunohistochemistry on tissue microarrays. Results: Gene expression and gene ontology analysis identified CXCL8 as an important chemokine which was more frequently up-regulated in GBM as compared to diffuse astrocytoma. Further we demonstrated localization of CXCL8 and its receptors in glioblastoma possibly affecting autocrine and paracrine signalling that promotes tumor cell proliferation and neovascularisation with vascular mimicry. Conclusion: From these results CXCL8 appears to be an important gliomagenic chemokine which may be involved in GBM growth by promoting tumor cell proliferation and neovascularization via vascular mimicry. Further in vitro and in vivo investigations are required to explore its potential candidature in anti-GBM therapy.