ClearCell FX: A microfluidic system for label-free circulating tumor cell enrichment.

Abstract

e22023 Background: Detection and characterization of rare circulating tumor cells (CTCs) are pivotal to early cancer detection and can provide insights into tumor biology leading to better cancer management. However, due to their extremely low abundance, CTC detection and enrichment has been a technical challenge. Although, many techniques and platforms have been recently developed to address problem, they are often limited to processing low sample volumes, are highly susceptible to clotting and frequently rely on antibodies for CTC capture. Methods: CTCs from metastatic Breast and Lung Cancer patients were enriched from peripheral blood using the Spiral microfluidic biochip and the automated ClearCell FX system. Blood was collected in EDTA tubes. After initial red blood cell lysis, the nucleated cellular fraction was loaded on the fully automated system, minimizing user steps and providing robust reproducible performance required for clinical use. Centrifugal forces inherent to spiral shaped microchannels enabled continuous, size-based enrichment of CTCs. Enriched CTCs were analysed by immunofluorescent staining. Detection of relevant mutations (ALK) was performed using fluorescence in situ hybrization (FISH). Results: The ClearCell FX performance was validated using cancer cell lines, achieving >50% recovery with 4log10 leukocyte depletion. The system can process 7.5 mL blood samples in an hour and the large channels dimensions eliminate any issues arising from channel clogging. CTCs were successfully detected in all samples collected from patients with metastatic lung and breast cancer (100% detection rate; n=40). FISH assays on the enriched cells showed good concordance for NSCLC samples harbouring EML4-ALK fusion mutations. Conclusions: The ClearCell FX provides a novel method to isolate CTCs from blood in their native state. The cells remain untagged with any antibodies and hence are more viable for propagation and other downstream analysis including PCR, next-generation sequencing (NGS) and FISH. The system addresses key challenges of the next generation CTC assays including antibody independent isolation, high sensitivity and throughput, and single-step retrieval of potentially viable CTCs.