BACR 17: Clinical evaluation of a novel microfluidic device for epitope-independent enrichment of circulating tumour cells in small cell lung cancer

Jakub Chudziak1,Deborah Burt1,Jenny Antonello1,Suzanne Dalby1,Dominic Rothwell1,Barbara Mesquita1,Daniel Morris1,Mahmood Ayub1,Sumitra Mohan1,Louise Carter1,2,Fiona Blackhall2,3,Caroline Dive1,Ged Brady1

1Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, Manchester, UK,2Christie NHS Foundation Trust, Manchester, UK,3Institute of Cancer Sciences, University of Manchester, Manchester, UK

Presenting date: Monday 2 November
Presenting time: 12.20-13.10

Background

Circulating tumour cells (CTCs) have potential utility as minimally-invasive biomarkers to aid treatment decision making. However, many CTC technologies (including the gold standard, CellSearchTM) that enrich CTCs based on expression of specific epitopes do not accommodate CTC heterogeneity and new epitope-independent methods are needed.

Method

The Parsortix device enriches CTCs based on size and rigidity. Initially, whole blood samples spiked with HT29 cells were maintained at room temperature for up to 4 days followed by plasma removal and direct application of cell pellets to the Parsortix device. The device was subsequently evaluated using preserved blood samples from small cell lung cancer patients. Presence of CTCs in enriched samples was evaluated using immunofluorescent labelling for pan-cytokeratin (epithelial marker), CD45 (leukocyte marker) as well as nuclear labelling. Following CTC enrichment DNA and RNA were extracted for downstream mutational analysis.

Results

Blood processing was optimised using spiked samples to generate plasma and CTCs from the same blood sample allowing direct comparison of circulating free DNA (cfDNA) and CTCs. The numbers of spiked cells recovered using the Parsortix device and CellSearchTM were not significantly different (p=0.23). DNA and RNA analysis of Parsortix enriched CTCs from clinical samples generated CTC specific profiles. Recovered CTCs were amenable to processes including immunocytochemistry, single cell isolation, whole genome amplification and mRNA analysis. For some SCLC patients, increased numbers of putative CTCs were detected by Parsortix enrichment compared to CTCs identified using EpCAM-positive selection (CellSearchTM).

Conclusion

The Parsortix device is a promising approach for routine patient blood monitoring for both molecular analysis of the entire enriched sample and single CTC isolation and genetic profiling. Furthermore, since this device is epitope-independent, it is suitable for analysis of both EpCAM-negative and EpCAM-positive CTCs and tumour types such as NSCLC where only a minority of patients have CellSearchTM detected CTCs.