545P - Next-generation sequencing of circulating tumor cells isolated from peripheral blood of patients with head and neck, and gastrointestinal cancer

Abstract

Background: Recently, precision medicine has gained attention for the prediction of therapeutic strategies in individual patients. Because the biological behavior of tumor cells has changed over time according to the pressures from treatment, real-time monitoring of tumor biology is needed to provide suitable information for choosing the most effective therapy for each patient. Circulating tumor cells (CTCs) can reflect current tumor status from primary sites and metastases from the bloodstream without invasive testing. In the current CTCs capture platforms of flow cytometry, gradient centrifugation, filtration, and droplets have been employed. A novel label-free inertial microfluidics approach (MFA) based on biomechanical properties has been developed at National Singapore University (Hou et al, Sci Rep 2013), and is able to capture CTCs independent of EpCAM expression. To identify genomic alterations in CTCs as basic data for precision medicine, we investigated the genomic profiling of CTCs using next-generation sequencing (NGS). Methods: Participants in this prospective study comprised 31 patients with advanced head and neck cancer (HN), esophageal cancer (EC), gastric cancer (GC), or colorectal cancer (CRC). CTCs were isolated using an MFA technique from 5 ml of whole blood. NGS was performed after whole-genome amplification (WGA) of DNA extracted from CTCs. Results: The underlying pathology was HN in 11 patients, EC in 8 patients, GC in 1 patient, and CRC in 11 patients. CTCs were detected from the peripheral blood of all patients (median number of CTCs, 14.5/ml; range, 3-133/ml). The most frequently detected mutations in CTCs were to APC, EGFR, RB1 and SMAD4 (10.5%) in HN and EC, and TP53 (27.2%), MET, RB1, and SMAD4 (18.2%) in CRC. NGS was successfully performed using WGA-treated DNA from CTCs and related material. Conclusions: We were able to effectively capture CTCs from patients with HN, EC, GC and CRC, and successfully performed NGS of CTCs using a microfluidic separation system without antibodies. Another trial is now ongoing to assess correlations between emergence of gene mutations in CTCs and changes in therapeutic effect during molecular-targeted therapy. Legal entity responsible for the study: Division of Early Detection for Cancer, National Cancer Center Research Institute Funding: None Disclosure: All authors have declared no conflicts of interest.