Abstract 2343: The incidence of BRAF mutation in non-small cell lung cancers is low in Korean patients

Abstract

Abstract Introduction: BRAF mutation is present in about 8% of all cancer. Oncogenic activity of BRAF V600E mutation was established in lung cancers. Dabrafenib and trametinib combination therapy is preferred first line therapy for advanced or metastatic lung cancer with BRAF V600E mutation. However, there is only little basic knowledge of BRAF mutational status among Korean population. In this study, BRAF mutation, particularly BRAF V600E mutational status was explored among Korean non-small cell lung cancer patients. The clinical and pathologic characteristics of BRAF V600E mutation in non-small cell lung cancers were also investigated. Materials and Methods: The final cohort was 378 cases of primary non-small cell lung cancers. Fromalin-fixed paraffin embedded (FFPE) tissue blocks were used. PNA-mediated clamping PCR for BRAF V600, BRAF V600E real-time PCR and immunohistochemistry for mutation specific monoclonal antibody of Ventana VE1 were performed on all 378 cases of non-small cell lung cancers. For positive cases, direct sequencing was performed for validation. Results: BRAF V600 mutation was detected in five cases using PNA clamping method among 378 non-small cell carcinoma cases. By using BRAF real-time PCR, a BRAF V600E mutation was detected in 3 patients among total 378 cohort. There were 2 discordant cases between PNA clamping and real-time PCR. On immunohistochemistry, 3 patients showed positive staining for tumor cytoplasm and all positive cases also had positive results in real-time PCR. Direct Sanger sequencing was done in 5 cases that had any positive results for 3 methods. The results of Sanger sequencing was the same with those of real-time PCR and immunohistochemistry. Direct sequencing using PAN PCR product was performed on 2 negative cases for validation. On sequencing using PNA clamping PCR product, all cases showed mutation for BRAF gene other than V600E genotype. Finally, there were 3 cases (0.8%) of BRAF V600E mutation and 2 cases of BRAF mutation (0.5%) other than V600E genotype. Among BRAF mutated patients, there were 2 never smokers and 3 ever smokers. All patients harboring BRAF mutation had no concomitant EGFR or ALK aberrations. Conclusion: BRAF mutation incidence is relatively lower than that of Western data set and similar to that of Japanese report. Immunohistochemistry for Ventana VE1 antibody can be a useful screening method to detect BRAF V600E mutation. Citation Format: Ahrong Kim, Hyo Yeong Ahn, Chang Hun Lee, Young Dae Kim, Min Ki Lee, Yeon Joo Jeong, So Jeong Lee. The incidence of BRAF mutation in non-small cell lung cancers is low in Korean patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2343.