Selection Strategies and Practical Application of BRAF V600E-Mutated Non–Small Cell Lung Carcinoma

PURPOSE: The incidence of BRAF V600E mutation in non–small cell lung carcinoma (NSCLC) is lower than 2%, which poses difficulties in finding legitimate patients for targeted therapy. We investigated the predictive factors pertaining to BRAF V600E and the effectiveness of the VE1 antibody as a screening method for patient selection. MATERIALS AND METHODS: The study was designed into two steps. In a first group, BRAF-mutated NSCLCs were identified from sequencing data to determine the features of BRAF V600E mutation. The results of the first group helped the collection of adenocarcinomas with a papillary or micropapillary pattern but without epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) alterations as a second group so that the frequency of BRAF V600E mutation could be calculated. The sensitivity and specificity of the VE1 were compared with BRAF V600E status. RESULTS: Among 39 BRAF-mutated NSCLCs in the first group, 20 (51%) were V600E. BRAF V600E mutation was more common in female patients and showed no significant correlation with smoking status. Nineteen cases were adenocarcinomas without EGFR and ALK alterations. The most common patterns of invasion were papillary and micropapillary along with central fibrosis. The sensitivity and specificity of the VE1 were 90.0% and 92.3%, respectively. In the second group, 6.7% of cases were VE1-positive, indicating that the prevalence was significantly higher than that reported in previous studies (0.3%–1.8%). CONCLUSION: BRAF V600E-mutated NSCLCs could be enriched with the application of clinicopathologic parameters, which are not perfect. Therefore, additional VE1 immunohistochemistry may be useful as a screening method.