Abstract 5588: Uneven distribution of CTCs in magnetic fields following binding with iron nanoparticles

Abstract

Abstract Circulating tumor cell (CTC) detection and characterization have recently become an integral part of precision medicine. Several large, multicenter clinical studies confirmed that the prevalence of CTC is a useful predictor of treatment efficacy in metastatic breast cancer. The number of CTCs is strongly correlated with clinical progression. Oncology clinics widely use this biomarker to provide prognostic information. There are several platforms to isolate and measure CTCs. The only FDA-approved method is the CellSearch system developed by Veridex. The CellSearch System uses anti-EpCAM antibodies and polymer-coated iron nanoparticles in order to isolate CTC with the use of a magnetic field. The enriched CTC fraction is then placed in a MagNest chamber and the transparent slide is read by the automatic fluorescent CellTracks Analyzer. By using prelabeled breast cancer cells as quality control (QC) samples, we semiquantitated the distribution of CTC cells on slides in eleven QC samples. We found that CTC cells distribute unevenly on the slides. In order to count all CTCs, the whole area of the slide is divided into 175 small regions by the manufacturer. To better quantitate the CTC number, it is important to have all cells evenly spread over the slide. Our results showed that 41 out of 175 regions contained higher QC CTC counts. The heat map indicates that the magnetic field lines may have an effect on CTC localization. The CTC platforms are susceptible for underestimating actual CTC counts. Our findings indicate that cell concentration in certain regions caused by a magnetic field effect could be one of several contributing factors. Citation Format: Chengsen Xue, Christina D. Swenson, Thomas W. Mc Closkey. Uneven distribution of CTCs in magnetic fields following binding with iron nanoparticles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5588.