Rapid genomic profiling of circulating tumor DNA in non-small cell lung cancer using Oncomine Precision Assay with GenexusTM integrated sequencer

Background: Genomic profiling of tumors from cancer patients facilitates molecular-guided therapy. The turnaround time is one of important issues to deliver results timely for clinical decisions. The Ion TorrentTM GenexusTM Integrated Sequencer automates all next generation sequencing workflows and delivers results within a day. Methods: In this study, we conducted a feasibility study to evaluate the detection rate of genomic alterations from cell-free total nucleic acid (cfTNA, containing cfDNA and cfRNA) of 119 non-small cell lung cancer using Oncomine Precision Assay on GenexusTM Integrated Sequencer. Oncomine Precision Assay (OPA) covers actionable mutations, copy number variations and fusion genes and that are applicable for the selection of targeted therapy. cfTNA isolated from plasma (derived from 14 ml of blood) were subjected to the Genexus system for library construction, templating, sequencing, and data analyses. Results: The sequencing resulted in median overall depth of 35,773X and median molecular coverage of 2,192X with cfTNA input ranged from 11-36ng. Among the 119 samples evaluated, we detected at least one genomic alteration in plasma cfTNA of 79 cases (66%). When comparing to standard-of-care testing, the sensitivity and specificity of mutation detection in non-small cell lung cancer related genes using liquid biopsy with Genexus-OPA ranged between 49-67% and 93-100%, respectively. 59% of actionable mutations, which were present in tumor tissues, were detected by the Genexus- Oncomine Precision Assay using plasma cfTNA. Among the 5 mutations detected from liquid biopsy only, three mutations are of level 1 evidence according to OncoKB database, highlighting the clinical utilities of liquid biopsy in addressing tumor heterogeneity. Extrathoracic metastasis and levels of lactate dehydrogenase (LDH), C-reactive protein (CRP) and Carcinoembryonic Antigen (CEA) are found to be associated with increased circulating tumor DNA detection. Conclusions: The GenexusTM Integrated Sequencer system is an automated, accurate NGS system with short TAT that could assist clinicians to make more timely decision.