Liquid biopsy-based analysis by ddPCR and CAPP-Seq in melanoma patients.

BACKGROUND: The development of BRAF/MEK inhibitors in patients with metastatic melanoma harboring BRAF mutations has garnered attention for liquid biopsy to detect BRAF mutations in cell-free DNA (cfDNA) using droplet digital PCR (ddPCR) or next-generation sequencing methods. OBJECTIVE: To investigate gene mutations in tumor DNA and cfDNA collected from 43 melanoma patients and evaluate their potential as biomarkers. METHODS: ddPCR and CAncer Personalized Profiling by deep Sequencing (CAPP-Seq) techniques were performed to detect gene mutations in plasma cfDNA obtained from patients with metastatic melanoma. RESULTS: Gene variants, including BRAF, NRAS, TP53, GNAS, and MET, were detectable in the plasma cfDNA, and the results were partially consistent with the results of those identified in the tissues. Among the variants examined, copy numbers of MET mutations were consistent with the disease status in two melanoma patients. CONCLUSION: Liquid biopsy using CAPP-Seq and ddPCR has the potential to detect tumor presence and mutations, especially when tissue biopsies are unavailable. MET mutations in cfDNA may be a potential biomarker in patients with metastatic melanoma.