Huang Wen-Kuan, Kuo Tseng-Tong, Wu Chiao-En, Cheng Hsin-Yi, Hsieh Chia-Hsun, Hsieh Jia-Juan, Shen Yung-Chi, Hou Ming-Mo, Hsu Todd, Chang John Wen-Cheng
Division of Hematology-Oncology, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
Department of Pathology, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
Asia Pac J Clin Oncol. 2016 Dec;12(4):403-408. doi: 10.1111/ajco.12574. Epub 2016 Aug 4.
The BRAF V600 mutation has been shown to be clinically meaningful in terms of both the prognosis and sensitivity of BRAF inhibitors in patients with metastatic melanoma. Recently, a BRAF V600E mutation-specific antibody, VE1, was generated for the detection of tumors bearing BRAF V600E mutations. To determine the clinical value of immunohistochemical testing, we compared the prevalence of mutant BRAF detected by VE1 with direct sequencing results.
Paraffin-embedded, formalin-fixed melanoma biopsies were analyzed for the BRAF mutation status by immunohistochemistry with the VE1 antibody. Sanger sequencing was applied to verify the immunohistochemical results.
A total of 73 melanoma cases with tumor samples from primary lymph nodes and metastatic sites were selected for this study. Direct sequencing demonstrated that 18 of 73 cases (24.6%) harbored the BRAF V600 mutation: 17 with V600E and one with V600K. All 18 tumors shown to harbor the BRAF V600E/K mutations were VE1-positive. One additional case was false-positive for VE1. The sensitivity and specificity of VE1 was 100% (18/18) and 98% (54/55), respectively. The overall concordance between the immunohistochemical method and direct sequencing was excellent (98.6%).
Our findings demonstrate that immunohistochemical analysis using VE1 constitutes a highly sensitive test for the detection of BRAF mutations and suggest that this cost-effective method is suitable as a rapid diagnostic approach complementary to molecular testing.
BRAF V600突变已被证明在转移性黑色素瘤患者的预后和BRAF抑制剂敏感性方面具有临床意义。最近，一种BRAF V600E突变特异性抗体VE1被用于检测携带BRAF V600E突变的肿瘤。为了确定免疫组化检测的临床价值，我们将VE1检测到的突变BRAF患病率与直接测序结果进行了比较。
采用VE1抗体免疫组化分析福尔马林固定石蜡包埋的黑色素瘤活检组织的BRAF突变状态。应用桑格测序法验证免疫组化结果。
本研究共选取73例黑色素瘤病例，其肿瘤样本来自原发淋巴结和转移部位。直接测序显示，73例中有18例（24.6%）携带BRAF V600突变：17例为V600E，1例为V600K。所有18例显示携带BRAF V600E/K突变的肿瘤均为VE1阳性。另有1例为VE1假阳性。VE1的敏感性和特异性分别为100%（18/18）和98%（54/55）。免疫组化方法与直接测序的总体一致性极佳（98.6%）。
我们的研究结果表明，使用VE1进行免疫组化分析是检测BRAF突变的高灵敏度检测方法，提示这种经济有效的方法适合作为分子检测的快速诊断补充方法。
