Evaluation of the liquid biopsy for the detection of BRAFV600E mutation in metastatic melanoma patients.

BACKGROUND

Circulating tumor cells (CTCs) and circulating cell free DNA (ccfDNA) represent a liquid biopsy of a tumor allowing real time disease monitoring especially in advanced stages of cancer, but their analysis is technically challenging.

OBJECTIVE

We aimed to demonstrate the feasibility of two different technical approaches to detect the BRAFV600E mutation in the liquid biopsy of 20 metastatic melanoma patients by using both the enriched CTC fraction and circulating ccfDNA from the same blood sample.

METHODS

We detected CTCs by a filtration method in 20 metastatic melanoma patients and detected the BRAFV600E variant on CTCs and ccfDNA by an allele-specific qPCR assay; the mutated samples were confirmed by ICE-COLD PCR followed by Sanger sequencing.

RESULTS

We found CTCs in 70% of the samples, and identified the BRAFV600E variant on CTCs. We correlated the results with those obtained on ccfDNA from the same blood draw. We found some discordant results between CTCs and ccfDNA.

CONCLUSIONS

Our results underline the importance of investigating both CTCs and ccfDNA in a liquid biopsy approach to melanoma patients.