This study investigated the sensitivity and specificity of immunohistochemical (IHC) analysis using an anti-BRAF antibody to detect the presence of the BRAF V600E mutation in patients with metastatic melanoma. A total of 100 patients with American Joint Committee on Cancer stage IIIC unresectable or stage IV melanoma and who underwent tumor DNA BRAF mutation testing were selected. Paraffin-embedded, formalin-fixed melanoma biopsies were analyzed for the BRAF mutation status by independent, blinded observers using both conventional DNA molecular techniques and IHC with the novel BRAF V600E mutant-specific antibody, VE1. The antibody had a sensitivity of 97% (37/38) and a specificity of 98% (58/59) for detecting the presence of a BRAF V600E mutation. Of the BRAF-mutated cases, none of the non-V600E cases (including V600K) stained positive with the antibody (0/11). There were 5 cases with discordant BRAF mutation results. Additional molecular analysis confirmed the immunohistochemically obtained BRAF result in 3 cases, suggesting that the initial molecular testing results were incorrect. Two of these patients would not have received a BRAF inhibitor on the basis of the initial false-negative mutation testing result. Two cases remained discordant. The reported IHC method is an accurate, rapid, and cost-effective method for detecting V600E BRAF mutations in melanoma patients. Clinical use of the V600E BRAF antibody should be a valuable supplement to conventional mutation testing and allow V600E mutant metastatic melanoma patients to be triaged rapidly into appropriate treatment pathways.
*Melanoma Institute Australia
Disciplines of †Medicine
**Surgery, The University of Sydney
Departments of ††Melanoma and Surgical Oncology
‡‡Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, Sydney
‡Department of Medical Oncology, Westmead Institute for Cancer Research, Westmead Millennium Institute, Westmead Hospital, Westmead, NSW, Australia
∥Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-Universität Heidelberg
¶Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany
#Department of Medicine I and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
G.V.L., J.S.W., D.C., A.v.D., R.A.S. contributed equally.
Conflicts of Interest and Source of Funding: Supported by Program Grant 402761 of the National Health and Medical Research Council of Australia (NHMRC), Translational Research Program Grant 05/TPG/1-01 of the Cancer Institute NSW, and an infrastructure grant to Westmead Millennium Institute by the Health Department of NSW through Sydney West Area Health Service. Westmead Institute for Cancer Research is the recipient of capital grant funding from the Australian Cancer Research Foundation. G.V.L. and R.A.S. are funded by the Cancer Institute New South Wales Fellowship program. The funding body had no role in the design or conduct of the study. Under a licensing agreement between Ventana Medical Systems Inc., Tucson, Arizona, and the German Cancer Research Center, D.C. and A.v.D. are entitled to a share of royalties received by the German Cancer Research Center on the sales of VE1 antibody. The terms of this arrangement are being managed by the German Cancer Research Center in accordance with its conflict of interest policies. R.F.K.—consultancies and honoraria to: Roche and GlaxoSmithKline; travel support: GlaxoSmithKline. G.V.L.—consultancies: Roche, Bristol-Myers Squibb, and GlaxoSmithKline; honoraria: Roche; travel support: GlaxoSmithKline and Roche; research support: Roche. R.A.S.—consultancies: Roche and GlaxoSmithKline; honoraria: Abbott Molecular. J.F.T.—consultancies: Roche and GlaxoSmithKline. For the remaining authors none were declared.
Correspondence: Georgina V. Long, MD, PhD, Melanoma Institute Australia and Westmead Hospital, 40 Rocklands Rd, North Sydney, NSW 2060, Australia (e-mail: email@example.com).