Abstract 3054: High-throughput microfluidic Labyrinth for the label-free isolation of circulating tumor cells

Abstract

Abstract Circulating tumor cells (CTCs) present in the blood are the instruments of metastasis and are of high biologic and clinical relevance. Single-cell technologies are playing an increasing role in profiling CTCs in the peripheral blood for detection and real-time monitoring of cancer metastasis. CTCs also help in identifying its distinct drivers. However, current approaches are limited to manual selection of CTCs, which hinders the unbiased comprehensive study of CTCs on a single-cell level. We present a unique label-free microfluidic “Labyrinth” device to isolate CTCs at a high throughput of 2.5mL/min, offering the first biomarker-independent single-cell isolation and genomic characterization platform to study heterogeneous CTC subpopulations in cancer patients. The Labyrinth takes advantage of inertial forces on the microscale in curved geometries to differentially focus cells based on their size. This novel strategy of multicourse path traversing across inner loops to outer loops yielding highest hydrodynamic path length enables focusing of white blood cells (WBCs), leading to high recoveries (> 90%) and efficient separation of WBCs from CTCs, resulting in high purity (~ 200 WBCs/mL), even in whole blood samples without any preprocessing. CTCs were successfully isolated from 56 breast cancer (9.1 CTCs/mL average, range 2-31/mL) and 20 pancreatic cancer (51.6 CTCs/mL average, range 11-115/mL) patients. We detected not only CTCs typically defined by epithelial markers, but also significant numbers of CTCs (>50%) lacking epithelial markers but expressing mesenchymal and cancer stem cell (CSC) markers. Patient samples were then analyzed using single-cell multiplex gene expression. Seventy single cells were successfully recovered and used to identify different subpopulations of CTCs based on their genetic signature, unlike other methods where a positive or negative selection based on protein expression is used. Interestingly, both inter- and intrapatient molecular heterogeneity at the single-cell level in CTCs were observed with cells expressing genes uniquely related to epithelial, MET, and EMT phenotypes. The Labyrinth platform allows a thorough molecular understanding of the heterogeneity among CTCs. This platform also shows CTCs' potential as a biomarker to noninvasively evaluate tumor progression and response to treatment in cancer patients. Citation Format: Eric Lin. High-throughput microfluidic Labyrinth for the label-free isolation of circulating tumor cells [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 3054.