Comparison of Three BRAF Mutation Tests in Formalin-Fixed Paraffin Embedded Clinical Samples
Soomin Ahn, Jeeyun Lee, Ji-Youn Sung, So Young Kang, Kyoung-Mee Kim. Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; School of Medicine, Kyung Hee University, Seoul, Republic of Korea
Background: Recently, BRAF inhibitors showed dramatic treatment outcome in BRAF V600 mutant melanoma. Therefore, the accuracy of BRAF mutation test is critical for proper patient selection who are indicated for BRAF inhibitors.
Design: A total of 64 tumors including 34 malignant melanomas, 16 papillary thyroid carcinomas, and 14 carcinomas from other primary sites were analyzed for BRAF mutation. BRAF mutations were detected by allele-specific PCR (AS-PCR) and direct sequencing and subsequently retested with a real-time PCR assay, cobas 4800 V600 mutation test. The results of cobas were directly compared to those of AS-PCR and direct sequencing.
Results: There was 90.6% concordance (58 of 64 tested samples) and 9.4% discordance among the 3 methods. Out of 6 discordant cases, 4 cases were melanomas and two cases were papillary thyroid carcinomas. Three cases were BRAF V600E positive only by cobas test, but were not detected by AS-PCR and direct sequencing. One melanoma patient with BRAF detected only by cobas test, but wild in both AS-PCR and direct sequencing has been on vemurafenib treatment for 6 months and showed a dramatic response to vemurafenib. AS-PCR failed to detect a V600K mutation in a case which was identified by direct sequencing and cobas test.
Conclusions: In conclusion, we directly compared cobas test with currently available AS-PCR and direct sequencing for BRAF mutation and found that cobas test is a reliable method to be applicable in small quantities of DNAs extracted from FFPE clinical samples.
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 260, Wednesday Morning