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Melanoma sample mutational status has previously been analysed using various PCR-based methods prior to BRAF-inhibitor treatment.1 However, among several others Long et al 2 describe BRAF V600E oncoprotein detection in melanoma using immunohistochemical (IHC) methods with the monoclonal antibody VE1. Here, we confirm the usefulness of BRAF V600E oncoprotein IHC detection in melanoma and therefore recommend BRAF V600E IHC screening combined with a sensitive and specific mutational analysis prior to BRAF inhibitor treatment to avoid false-negative results.
Materials and methods
BRAF V600E IHC expression was compared with BRAF mutation status in a cohort of 28 formalin-fixed paraffin-embedded cutaneous melanoma samples (primary tumours, median Breslow 1.12 mm) using five different PCR-based methods and the monoclonal antibody VE1. All samples were used within 1 year of diagnosis and collected from the same laboratory during a time-period of 1 year with no change in sampling method or storage conditions. Cohort description and mutation analysis results using Cobas 4800 BRAF V600 Mutation Test (Roche A/S, Hvidovre, Denmark), Sanger sequencing, Competitive Amplification of Differentially Melting Amplicons, pyrosequencing and TaqMan have been previously published.1 We have now added the mutation analysis Therascreen BRAF RGQ PCR kit (Qiagen, Manchester, UK) to specify the BRAF mutation subtype in samples with a weak IHC stain and with ambiguous mutational test results.1 This assay detects five BRAF mutations (V600E (c.1799 T>A), V600E complex (V600Ec; c.1799_1800 TG>AA), V600D (c.1799_1800 TG>AT), V600R (c.1798_1799 GT>AG) …