Diagnostic value of immunohistochemistry for the detection of the BRAFV600E mutation in primary lung adenocarcinoma Caucasian patients

Background: Non-small-cell lung carcinoma (NSCLC) patients with a BRAF(V600E) mutation benefit from targeted therapy. The usefulness of immunohistochemistry (IHC) as an alternative approach for the detection of BRAF(V600E) in NSCLC patients has not been evaluated until now. This study compared the specificity and sensitivity of IHC with other methods for the detection of BRAF(V600E) in primary lung adenocarcinoma. Patients and methods: BRAF mutations were analysed by DNA sequencing of a Caucasian subpopulation of selected 450 of 1509 (30%) EGFR, KRAS, PI3KA, Her2 and EML4-ALK wild-type (wt) primary lung adenocarcinomas. Detection of the BRAF(V600E) mutation was carried out by IHC using the VE1 clone antibody and compared with the results of other molecular methodologies. Results: Of 450 (9%) of tumours, 40 harboured a BRAF mutation, which corresponded to either a BRAF(V600E) or a non-BRAF(V600E) mutation in 21 of 450 (5%) and 19 of 450 (4%) cases, respectively. The IHC VE1 assay was positive in 19 of 21 (90%) BRAF(V600E) E-mutated tumours and negative in all BRAF(nonV600E)-mutated tumours. Conclusion: IHC using the VE1 clone is a specific and sensitive method for the detection of BRAF(V600E) and may be an alternative to molecular biology for the detection of mutations in NSCLC.