Use of Cobas 4800 BRAF mutation test for the analysis of BRAF V600 mutations in cytological samples (CS) from metastatic melanoma (MM).

8572 Background: Vemurafenib is currently the most active first-line treatment in MM patients that harbor BRAF-V600E mutations. The Cobas 4800 BRAF V600 Mutation Test is an FDA-approved, CE-marked test that identifies formalin-fixed-paraffin-embedded samples (FFPE) carrying the BRAF V600E mutation. Fine needle aspirates are frequently the only samples available in MM patients, but the use of CS has not been validated in this platform. We have evaluated the capability to identify BRAF-V600E mutations in CS of MM with the Cobas 4800 BRAF Mutation Test, and results have been compared to the conventional Sanger direct sequencing method. Methods: BRAF mutations have been studied in 117 samples from 98 MM patients with the conventional Sanger method: 37 (32%) FFPE and 80 (68%) CS. DNA was extracted from 4-micron sections in FFPE and from stained smears in CS. All CS contained >50% of tumor cells. In a second step, 57 out of the 117 samples have been studied using Cobas (25 CS and 32 FFPE). In CS, Nucleospin Tis...