Identification of Potential Genomic Alterations Using Pan-Cancer Cell-Free DNA Next-Generation Sequencing in Patients With Gastric Cancer

Background: Molecular cancer profiling may lead to appropriate trials for molecularly tar -geted therapies. Cell-free DNA (cfDNA) is a promising diagnostic and/or prognostic bio-marker in gastric cancer (GC). We characterized somatic genomic alterations in cfDNA of patients with GC.Methods: Medical records and cfDNA data of 81 patients diagnosed as having GC were reviewed. Forty-nine and 32 patients were tested using the Oncomine Pan-Cancer Cell -Free Assay on the Ion Torrent platform and AlphaLiquid 100 kit on the Illumina platform, respectively.Results: Tier I or II alterations were detected in 64.2% (52/81) of patients. Biomarkers for potential targeted therapy were detected in 55.6% of patients (45/81), and clinical trials are underway. ERBB2 amplification is actionable and was detected in 4.9% of patients (4/81). Among biomarkers showing potential for possible targeted therapy, TP53 mutation (38.3%, 35 variants in 31 patients, 31/81) and FGFR2 amplification (6.2%, 5/81) were detected the most. Conclusions: Next-generation sequencing of cfDNA is a promising technique for the molecular profiling of GC. Evidence suggests that cfDNA analysis can provide accurate and re-liable information on somatic genomic alterations in patients with GC, potentially replacing tissue biopsy as a diagnostic and prognostic tool. Through cfDNA analysis for molecular profiling, it may be possible to translate the molecular classification into therapeutic tar -gets and predictive biomarkers, leading to personalized treatment options for patients with GC in the future.