Survival based on BRAF detection in combined tissue and liquid biopsy in melanoma
Description
Liquid biopsy provides a suitable option with progressively improved sensitivity and specificity to complement or to substitute the information obtained by regular biopsy. Extracellular vesicles (EVs) are emerging as powerful tools for providing information about the tumor and its microenvironment. The present study compares the information provided by tissue and EV-based liquid biopsy for the determination of BRAF status (BRAFV600E mutation or BRAF wild type) and analyzes their prognostic capacity. This data set suggests that combination of information from liquid and tissue biopsy regarding BRAF status in melanoma patients identifies the presence of BRAF mutation as a negative prognostic factor for short term survival in melanoma patients whereas individual analyses fail to stratify patients according their survival.
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We have evaluated a cohort of 22 patients for whom routine clinical BRAF mutation analysis in resected tissue took place after the first dermatologist visit using cobas® BRAF V600 Mutation Test. In addition, plasma was collected after tissue biopsy at a median time gap of two months and we have applied a combined cfDNA and EV-associated nucleic acid approach followed by an allele-specific PCR for BRAFV600E mutation (García-Silva et al., 2019). Collection and freezing of plasma were performed in EDTA-tubes in less than 1-2 hours. Isolation of exosomal RNA and DNA along with any cfDNA was performed using ExoLution Plus Extraction kit (Exosome Diagnostics). The total isolated nucleic acids were subjected to reverse transcription and preamplification of the BRAF gene followed by a quantitative PCR reaction for mutant BRAF allele.