title: Immunohistochemistry is highly sensitive and specific for the detection of V600E BRAF mutation in melanoma.
abstract: This study investigated the sensitivity and specificity of immunohistochemical (IHC) analysis using an anti-BRAF antibody to detect the presence of the BRAF V600E mutation in patients with metastatic melanoma. A total of 100 patients with American Joint Committee on Cancer stage IIIC unresectable or stage IV melanoma and who underwent tumor DNA BRAF mutation testing were selected. Paraffin-embedded, formalin-fixed melanoma biopsies were analyzed for the BRAF mutation status by independent, blinded observers using both conventional DNA molecular techniques and IHC with the novel BRAF V600E mutant-specific antibody, VE1. The antibody had a sensitivity of 97% (37/38) and a specificity of 98% (58/59) for detecting the presence of a BRAF V600E mutation. Of the BRAF-mutated cases, none of the non-V600E cases (including V600K) stained positive with the antibody (0/11). There were 5 cases with discordant BRAF mutation results. Additional molecular analysis confirmed the immunohistochemically obtained BRAF result in 3 cases, suggesting that the initial molecular testing results were incorrect. Two of these patients would not have received a BRAF inhibitor on the basis of the initial false-negative mutation testing result. Two cases remained discordant. The reported IHC method is an accurate, rapid, and cost-effective method for detecting V600E BRAF mutations in melanoma patients. Clinical use of the V600E BRAF antibody should be a valuable supplement to conventional mutation testing and allow V600E mutant metastatic melanoma patients to be triaged rapidly into appropriate treatment pathways.
authors.affiliation: Melanoma Institute Australia and Westmead Hospital, 40 Rocklands Rd, North Sydney, NSW 2060, Australia. georgina.long@sydney.edu.au
authors.forename: Georgina V
authors.initials: GV
authors.lastname: Long
authors.forename: James S
authors.initials: JS
authors.lastname: Wilmott
authors.forename: David
authors.initials: D
authors.lastname: Capper
authors.forename: Matthias
authors.initials: M
authors.lastname: Preusser
authors.forename: Yuxiao E
authors.initials: YE
authors.lastname: Zhang
authors.forename: John F
authors.initials: JF
authors.lastname: Thompson
authors.forename: Richard F
authors.initials: RF
authors.lastname: Kefford
authors.forename: Andreas
authors.initials: A
authors.lastname: von Deimling
authors.forename: Richard A
authors.initials: RA
authors.lastname: Scolyer
mesh_terms: D000911:Antibodies, Monoclonal / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D009154:Mutation; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics* / Q000378:metabolism; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf