BRAF V600E mutation and BRAF VE1 immunoexpression profiles in different types of glioblastoma.

Abstract

Abnormalities in proto-oncogene B-Raf (BRAF) are typical in several subgroups of gliomas, including pilocytic astrocytomas, optic nerve gliomas, pleomorphic xanthoastrocytomas (PXA), anaplastic PXAs and gangliogliomas. However, they are rarely reported in adult gliomas. BRAF alterations are frequent in a distinct variant of glioblastomas (GBMs) known as epithelioid GBMs (E-GBMs). There are limited studies on whether immunohistochemistry (IHC) can be used to determine the presence of BRAF VE1 mutations in these tumors. The aim of the current study was to examine BRAF V600E mutations in 20 GBMs, including GBMs with epithelioid features, giant cell GBMs and conventional GBMs. V600 mutations were detected using the Cobas 4800 BRAF V600 Mutation Test, and IHC analysis was also performed. Of the 6 cases of GBM with epithelioid features, 1 exhibited a BRAF V600E mutation, while the other cases did not. IHC staining was positive in 3 out of the 8 conventional GBMs. Vemurafenib is a targeted therapy that has mainly been used for the treatment of melanoma patients for several years, and as a possible alternative treatment for cases of GBM harboring BRAF mutations, its existence may make testing for BRAF status important.