Glioma 2021 WHO Classification: The Superiority of NGS Over IHC in Routine Diagnostics

Abstract

Introduction The accurate detection of genetic variants such as single substitutions ( IDH1/2 , TERT ), chromosomal abnormalities ( CDKN2A , 1p/19q deletions, and EGFR amplifications), or promoter methylations ( MGMT ) is critical for glioma patient management, as emphasized in the World Health Organization's (WHO’s) most recent classification in 2021 (WHO CNS5). The purpose of this study was to evaluate novel innovative methods for determining IDH1/2 status in the context of WHO CNS5. Methods Multiple biomarkers were simultaneously screened using next-generation sequencing (NGS) on 34 glioma samples. In cases where the IDH1/2 status determined by immunohistochemistry (IHC) or multiplex ligation-dependent probe amplification (MLPA) was inconsistent with the NGS results, quantitative polymerase chain reaction (qPCR) and Sanger sequencing were performed to resolve the adjudicated discrepancy. Results IDH1/2 NGS results differ from IHC (7/13 samples) as well as MLPA reports (1/4 samples). All NGS findings were confirmed by qPCR and Sanger sequencing. WHO CNS5 requires assessment of multiple mutations for glioma classification. Conclusions We demonstrated that qPCR or NGS performed in reference genetic laboratories, rather than IHC, is the most reliable method for IDH1/2 analysis. Clinicians should be aware of discrepancies in MLPA or IHC results and seek reconsultation in facilities with extensive access to advanced molecular technologies. Moreover, we proposed a new algorithm for the molecular diagnostic procedures in glioma patients based on the WHO CNS5. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s40291-022-00612-3.

Construction and validation of a cuproptosis-related prognostic model for glioblastoma

“…Some GBM patients have a relatively long survival time, while others show a highly malignant outcome. WHO classification, the traditional histopathological diagnosis method, cannot accurately reflect the characteristics of GBM ( 14 ). It is of great clinical significance to explore novel prognostic markers and selectively administer different therapeutic strategies ( 15 ).…”

Evaluation of the rapid Idylla IDH1-2 mutation assay in FFPE glioma samples

“…The benefits of immunohistochemistry are that it requires only a single slide, has a rapid TAT, and can be evaluated by the surgical pathologist as part of immunohistochemical workup, but the most commonly used antibody clone can only detect the IDH1 p.R132H alteration [ 7 ]. Next-generation sequencing methods are more comprehensive and can detect any oncogenic missense alteration in IDH1 or IDH2 [ 8 ], but sequencing requires a high DNA input and the TAT can be over two weeks. Therefore, a method that combines benefits of both assays -- rapid TAT, minimal material, and ability to detect any alteration in IDH1/2 -- would be ideal.…”

Recapitulating the Key Advances in the Diagnosis and Prognosis of High-Grade Gliomas: Second Half of 2021 Update

“…New tumor types and subtypes were introduced, and some of them are based on technologic advances such as next-generation sequencing (NGS) and DNA methylome profiling, with over 40 tumor types and subtypes eventually being defined by their key molecular features [ 9 ]. To merely note a couple of examples, the accurate detection of genetic variants such as single substitutions (in idh1/2 and tert genes), chromosomal abnormalities ( CDKN2A , 1p/19q deletions, and EGFR amplifications), and promoter methylations ( MGMT ) became critical for HGG patient management, and new techniques such as quantitative polymerase chain reaction (qPCR) and NGS became more reliable with respect to the reliability of older ones such as IHC [ 10 ]. This had consequences on treatment planning as well; based on molecular profiling, the American Society for Radiation Oncology (ASTRO) task force proposed recommendations concerning the RT management of molecularly characterized HGG patients, including the possible use of intensity-modulated RT/volumetric-modulated arc therapy or proton therapy [ 11 ].…”