title: Prospective immunohistochemical analysis of BRAF V600E mutation in melanoma.
abstract: The v-raf murine sarcoma viral oncogene homolog B1 (BRAF) V600E mutation is the most common activating genetic alteration of this oncogene and a predictive marker for the therapeutic use of BRAF inhibitors in melanoma. Our aim was to evaluate the performance of BRAF V600E mutation-specific monoclonal antibody (VE1) in a prospective diagnostic setting of melanoma patients (n = 102). All 41 cases (40.2%) that showed a V600E mutation in the cyclic minisequencing analysis of the DNA were also initially scored immunopositive. Two cases that were scored as BRAF V600E mutation positive by immunohistochemistry were negative in the DNA-based mutation analysis and determined to be immunonegative in a repeated staining with more representative specimens. Thus, BRAF V600E mutation detection using immunohistochemistry was 100% sensitive and 96.8% specific, when compared with the analysis of the DNA. None of the BRAF V600K mutations was detected by the VE1 antibody (n = 7). However, the VE1 antibody detected a rare V600E2 mutation. We also studied the role of BRAF V600E mutation in a set of melanoma patients who had been investigated for sentinel node metastasis. Melanoma lymph node metastases were diagnosed in 21.8% (12/55) of the sentinel nodes, and BRAF V600E immunopositivity was detected in 34.5% (19/55) of the cases. BRAF V600E mutation status did not correlate with any clinicopathological parameters. In conclusion, analysis of BRAF V600E mutation in melanoma by immunohistochemistry is a sensitive and specific method, which can be used to identify BRAF inhibitor-sensitive melanoma patients as a first-line method due to its rapid and affordable nature.
authors.affiliation: Department of Pathology, HUSLAB and Haartman Institute, Helsinki University Central Hospital, 00029 Helsinki, Finland; University of Helsinki, 00014 Helsinki, Finland; Genome-Scale Biology, Research Programs Unit, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Thiel
authors.affiliation: Department of Pathology, HUSLAB and Haartman Institute, Helsinki University Central Hospital, 00029 Helsinki, Finland; University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Monica
authors.initials: M
authors.lastname: Moza
authors.affiliation: Laboratory of Genetics, HUSLAB, Helsinki University Central Hospital, HUSLAB, 00029 Helsinki, Finland.
authors.forename: Soili
authors.initials: S
authors.lastname: Kytölä
authors.affiliation: Laboratory of Genetics, HUSLAB, Helsinki University Central Hospital, HUSLAB, 00029 Helsinki, Finland.
authors.forename: Arto
authors.initials: A
authors.lastname: Orpana
authors.affiliation: Department of Plastic Surgery, Helsinki University Central Hospital, 00029 Helsinki, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Jahkola
authors.affiliation: Department of Oncology, Helsinki University Central Hospital, 00029 Helsinki, Finland.
authors.forename: Micaela
authors.initials: M
authors.lastname: Hernberg
authors.affiliation: Department of Pathology, HUSLAB and Haartman Institute, Helsinki University Central Hospital, 00029 Helsinki, Finland; University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Susanna
authors.initials: S
authors.lastname: Virolainen
authors.affiliation: Department of Pathology, HUSLAB and Haartman Institute, Helsinki University Central Hospital, 00029 Helsinki, Finland; University of Helsinki, 00014 Helsinki, Finland; Genome-Scale Biology, Research Programs Unit, University of Helsinki, 00014 Helsinki, Finland. Electronic address: ari.ristimaki@helsinki.fi.
authors.forename: Ari
authors.initials: A
authors.lastname: Ristimäki
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D004252:DNA Mutational Analysis / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D009154:Mutation / Q000235:genetics*; D011446:Prospective Studies; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF; Macrophages; Melanoma; Pigment; Prospective; Sentinel node; V600