Pathology Department Angers University Hospital Angers France.
Genetics and Biochemistry Department Angers University Hospital Angers France.
Brain Behav. 2017 Feb 10;7(3):e00641. doi: 10.1002/brb3.641. eCollection 2017 Mar.
Some glial-neuronal tumors (GNT) (pleomorphic xantho-astrocytoma [PXA], ganglioglioma [GG]) display BRAF-V600E mutation, which represents a diagnostic clue to these entities. Targeted therapies against BRAF-V600 protein have shown promising results in GNT. The aim of this study was to assess the utility of BRAF-V600E immunohistochemistry (IHC, clone VE1) in daily practice in a series of 140 glial, and GNT compared to molecular biology (MB) techniques.
We performed BRAF-V600E IHC on all 140 cases. We used Sanger sequencing and allele-specific quantitative PCR (ASQ-PCR) to detect BRAF-V600E mutation when sufficient amount of materiel was available.
BRAF-V600E immunostaining was detected in 29.5% of cases (41/140 cases; 61.5% GG/GC/AGG (32/52), 33% PXA, 6.6% pilocytic astrocytomas). In 47 cases, MB could be performed: Sanger sequencing and ASQ-PCR in 34 cases, ASQ-PCR only in 11 cases, and Sanger sequencing only in two cases. In initial tumors, Sanger sequencing identified BRAF-V600E mutation in 19.5% tumors (seven of 36 tested cases). ASQ-PCR showed mutation in 48.5% tumors (17/35 tested cases). In six cases (5 GG, one PXA), the results were discordant between IHC and MB; the five GG cases were immunopositive for BRAF-V600E but wild type with both MB techniques. In another 7 GG, the percentage of mutated (ganglion) cells was low, and Sanger sequencing failed to detect the mutation, which was detected by IHC and ASQ-PCR.
In tumors with few mutated cells (e.g., GG), anti-BRAF-V600E IHC appears more sensitive than Sanger sequencing. The latter, although considered as the gold standard, is not to be used up-front to detect BRAF mutation in GG. The combination of IHC and ASQ-PCR appears more efficient to appraise the indication of targeted therapies in these glioneuronal tumors.
一些神经胶质神经元肿瘤（GNT）（多形性黄色星形细胞瘤[PXA]，神经节细胞瘤[GG]）显示 BRAF-V600E 突变，这是这些实体的诊断线索。针对 BRAF-V600 蛋白的靶向治疗在 GNT 中显示出了有前景的结果。本研究的目的是评估 BRAF-V600E 免疫组化（IHC，克隆 VE1）在一系列 140 例神经胶质和 GNT 中的实际应用，与分子生物学（MB）技术相比。
我们对所有 140 例病例进行了 BRAF-V600E IHC 检测。当有足够的材料时，我们使用 Sanger 测序和等位基因特异性定量 PCR（ASQ-PCR）来检测 BRAF-V600E 突变。
29.5%的病例（41/140 例；61.5% GG/GC/AGG（32/52），33% PXA，6.6%毛细胞星形细胞瘤）检测到 BRAF-V600E 免疫染色。在 47 例病例中，可以进行 MB 检测：Sanger 测序和 ASQ-PCR 在 34 例病例中进行，ASQ-PCR 仅在 11 例病例中进行，Sanger 测序仅在 2 例病例中进行。在初始肿瘤中，Sanger 测序在 19.5%的肿瘤（36 例检测病例中的 7 例）中发现 BRAF-V600E 突变。ASQ-PCR 显示 48.5%的肿瘤（35 例检测病例中的 17 例）存在突变。在 6 例病例（5 例 GG，1 例 PXA）中，IHC 和 MB 的结果不一致；5 例 GG 病例 BRAF-V600E 免疫阳性，但两种 MB 技术均为野生型。在另外 7 例 GG 中，突变（神经节）细胞的比例较低，Sanger 测序未能检测到突变，而 IHC 和 ASQ-PCR 则检测到了突变。
在肿瘤细胞中存在少量突变（如 GG）的情况下，抗 BRAF-V600E IHC 比 Sanger 测序更敏感。虽然 Sanger 测序被认为是金标准，但不建议在 GG 中首先使用该技术来检测 BRAF 突变。IHC 和 ASQ-PCR 的结合在评估这些神经胶质神经元肿瘤的靶向治疗指征方面更为有效。
