title: Assessment of BRAF V600E mutation status by immunohistochemistry with a mutation-specific monoclonal antibody.
abstract: Activating mutations of the serine threonine kinase v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) are frequent in benign and malignant human tumors and are emerging as an important biomarker. Over 95% of BRAF mutations are of the V600E type and specific small molecular inhibitors are currently under pre-clinical or clinical investigation. BRAF mutation status is determined by DNA-based methods, most commonly by sequencing. Here we describe the development of a monoclonal BRAF V600E mutation-specific antibody that can differentiate BRAF V600E and wild type protein in routinely processed formalin-fixed and paraffin-embedded tissue. A total of 47 intracerebral melanoma metastases and 21 primary papillary thyroid carcinomas were evaluated by direct sequencing of BRAF and by immunohistochemistry using the BRAF V600E mutation-specific antibody clone VE1. Correlation of VE1 immunohistochemistry and BRAF sequencing revealed a perfect match for both papillary thyroid carcinomas and melanoma metastases. The staining intensity in BRAF V600E mutated tumor samples ranged from weak to strong. The generally homogenous VE1 staining patterns argue against a clonal heterogeneity of the tumors investigated. Caution is essential when only poorly preserved tissue is available for VE1 immunohistochemical analysis or when tissues with only little total BRAF protein are analyzed. Immunohistochemistry using antibody VE1 may substantially facilitate molecular analysis of BRAF V600E status for diagnostic, prognostic, and predictive purposes.
authors.affiliation: Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 220/221, 69120 Heidelberg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Capper
authors.forename: Matthias
authors.initials: M
authors.lastname: Preusser
authors.forename: Antje
authors.initials: A
authors.lastname: Habel
authors.forename: Felix
authors.initials: F
authors.lastname: Sahm
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ackermann
authors.forename: Genevieve
authors.initials: G
authors.lastname: Schindler
authors.forename: Stefan
authors.initials: S
authors.lastname: Pusch
authors.forename: Gunhild
authors.initials: G
authors.lastname: Mechtersheimer
authors.forename: Hanswalter
authors.initials: H
authors.lastname: Zentgraf
authors.forename: Andreas
authors.initials: A
authors.lastname: von Deimling
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D001932:Brain Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000556:secondary; D002291:Carcinoma, Papillary / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D008545:Melanoma / Q000175:diagnosis / Q000378:metabolism / Q000556:secondary; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation / Q000235:genetics*; D011237:Predictive Value of Tests; D011379:Prognosis; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics* / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf