Immunohistochemical Analysis of BRAFV600E: More to Learn

High specificity and sensitivity make VE1 a fast and cost-effective tool for the detection of BRAFV600E protein.

BRAF mutation is the most common genetic abnormality in patients with disseminated melanoma. The mutated BRAFV600E protein has become an important therapeutic target in these patients. VE1 is a new monoclonal antibody that can identify mutated BRAFV600E. These authors and the authors of another recent study assessed the sensitivity and specificity of VE1 for detecting BRAF mutations in primary and metastatic melanoma lesions.

These researchers examined 44 melanomas metastasized to skin, lymph node, soft tissue, lung, and other locations; of these, 22 were BRAFV600E-positive. They also examined 20 primary melanomas (10 superficial spreading type, 3 acral, 3 lentigo maligna, 3 nodular, and 1 spitzoid), 7 of which were BRAFV600E-positive. All metastatic melanomas with the BRAFV600E mutation stained positive with the VE1 antibody; most showed a diffuse strong reaction, but tumors with weak local expression were also noted. No metastatic melanomas lacking the BRAFV600E mutation reacted to VE1. Among primary tumors, 70% of the superficial spreading melanomas were positive for VE1; all others of any type were negative. In one case, both a nevus and a tumor were positive for VE1, the melanoma more intensely. All cases were positive for melan-A regardless of BRAF mutation status. Other tested melanocytic markers (for MITF-1, tyrosinase, and gp100) were expressed to different degrees.

CITATION(S):

Busam KJ et al. Immunohistochemical analysis of BRAFV600E expression of primary and metastatic melanoma and comparison with mutation status and melanocyte differentiation antigens of metastatic lesions. Am J Surg Pathol 2013 Mar; 37:413.