Molecular and clinical heterogeneity of adult diffuse low-grade IDH wild-type gliomas: assessment of TERT promoter mutation and chromosome 7 and 10 copy number status allows superior prognostic stratification

Excerpt

With the 2016 revision of the World Health Organization classification of tumors of the central nervous system (WHO 2016) testing for the presence of mutations in isocitrate dehydrogenase 1 and 2 (IDH) and chromosome 1p/19q status is the cornerstone of glioma classification [5]. Approximately 80% of diffuse low-grade (grades II and III) gliomas (DLGG) are IDH mutated and have a relatively favorable prognosis compared to their IDH wild-type (IDHwt) counterparts [2]. The prognosis of IDHwt DLGG is almost similar to primary glioblastoma and genetic aberrations that are seen in primary glioblastoma are also reported in IDHwt DLGG: the combination of trisomy of whole chromosome 7 and loss of chromosomal arm 10q (+ 7/− 10q), and telomerase reverse transcriptase gene promoter (TERTp) mutations [2, 6, 7]. However, + 7/− 10q or TERTp mutations are not part of the WHO 2016 criteria and not all IDHwt DLGG have these specific molecular aberrations [2, 5]. Although clinical trials have not been performed, in view of their poor prognosis, aggressive treatment regimens for IDHwt DLGG have been suggested. However, as this is not a well-defined separate entity, the question remains whether IDHwt DLGG classified according to current WHO classification qualifies as a single entity, with sufficient information to estimate prognosis adequately, and therefore, guide treatment, or if the assessment of additional markers is necessary and if so which. A recent study by Aibaidula et al. showed that IDHwt DLGG are prognostically heterogeneous and that markers like TERTp, EGFR amplification and H3F3A mutation could be of additional value [1]. The prognostic role of + 7/− 10q and its relationship with TERTp mutations were not reported, however. In this study, we report on the impact of additional molecular markers, including + 7/− 10q and TERTp, on overall survival in adult IDHwt DLGG. …