Validation of the <scp>VE1</scp> immunostain for the <i><scp>BRAF</scp></i><scp>V600E</scp> mutation in melanoma

Abstract

BACKGROUND: BRAF mutation status, and therefore eligibility for BRAF inhibitors, is currently determined by sequencing methods. We assessed the validity of VE1, a monoclonal antibody against the BRAF V600E mutant protein, in the detection of mutant BRAF V600E melanomas as classified by DNA pyrosequencing. METHODS: The cases were 76 metastatic melanoma patients with only one known primary melanoma who had had BRAF codon 600 pyrosequencing of either their primary (n = 19), metastatic (n = 57) melanoma, or both (n = 17). All melanomas (n = 93) were immunostained with the BRAF VE1 antibody using a red detection system. The staining intensity of these specimens was scored from 0 to 3+ by a dermatopathologist. Scores of 0 and 1+ were considered as negative staining while scores of 2+ and 3+ were considered positive. RESULTS: The VE1 antibody showed a sensitivity of 85% and a specificity of 100% as compared to DNA pyrosequencing results. There was 100% concordance between VE1 immunostaining of primary and metastatic melanomas from the same patient. V600K, V600Q, and V600R BRAF melanomas did not positively stain with VE1. CONCLUSIONS: This hospital-based study finds high sensitivity and specificity for the BRAF VE1 immunostain in comparison to pyrosequencing in detection of BRAF V600E in melanomas.