Abstract 4967: Label-free collection of prostate circulating tumor cells using microfluidic Vortex technology
Authors: Pao Edward , Renier Corinne , Lemaire Clementine , Che James , Matsumoto Di Carlo Melissa , Triboulet Melanie , Srivinas Sandy , Jeffrey Stefanie S. , Kulkarni Rajan P. , Rettig Matthew , Sollier Elodie , Di Carlo Dino 
Published: July 2016

Abstract
BACKGROUND
Prostate cancer is among the most common cancers in men worldwide. Better markers than Prostate Specific Antigen (PSA) are still needed for the detection and monitoring of disease progression. Circulating Tumor Cells (CTCs) are shed into the blood stream from primary tumor(s) and may play key roles in the metastatic process. Liquid biopsies have emerged as a promising approach, with a correlation between the CTC numbers and patient prognosis for prostate cancer. CTCs have also been shown to enable early detection of recurrence, and could be potential candidates for guiding cancer therapy in real-time [1]. Current CTC enrichment technologies, including immuno-affinity and size-based filtration methods, have focused on high capture efficiency with sometimes tedious sample preparation and overall low purity.
METHOD
Here, we describe the use of the microfluidic Vortex Chip [2] for rapid and size-based isolation of CTCs from the blood of 23 patients with advanced prostate cancer, and 10 healthy donors; 5 being &lt;30 years old, 5 age-matched with the patient cohort. Requiring no upstream sample preparation, blood was diluted 10-fold and processed through the highly parallelized Vortex Chip at 8 mL/min (800 μL/min whole blood). Larger cells (predominantly CTCs) were captured in microscale vortices produced on the Chip, released into a small volume and collected off-chip for CK, PSA, CD45 and DAPI immunostaining and enumeration.
RESULTS
Preliminary work with LNCaP prostate cancer cells spiked in blood showed a 29% capture efficiency and 50% purity. In vitro cell assays confirmed that cells enriched with Vortex chip were alive and proliferating for up to 7 days. For 23 patient samples, CTCs were captured (0.5 - 20 CTCs/mL) with high purity (3.6 - 72.3%), in less than 1H, without prior sample preparation. 11.5% of the cells collected were CK and PSA-negative, but some were identified as undergoing epithelial-mesenchymal transition (EMT) following staining for vimentin and N-cadherin. Few atypical cells were also isolated from age-matched healthy donors (0.7 - 2.8 CTCs/mL), while none was detected in younger healthy donors. Using a threshold calculated from the age-matched healthy donors (3.31 CTCs/mL = mean + 2CV), 70% of the patients were characterized as “positive for CTCs”. No correlation was found between CTC counts and elevated PSA level.
CONCLUSION
These results demonstrate the ability to rapidly collect pure populations of CTCs in metastatic prostate cancer, independent of surface marker expression, without prior sample preparation. Future studies will use chips with optimized capture performance, sample recycling, and will include CTC molecular analysis by targeted panel sequencing. A larger cohort of healthy donors is also being examined to determine a statistically-robust CTC baseline for this size-based capture approach.
[1] Scher Hi, et al., J. Clin. Oncol. 2015
[2] Sollier E, et al., Lab Chip 2014
Citation Format: Edward Pao, Corinne Renier, Clementine Lemaire, James Che, Melissa Matsumoto Di Carlo, Melanie Triboulet, Sandy Srivinas, Stefanie S. Jeffrey, Rajan P. Kulkarni, Matthew Rettig, Elodie Sollier, Dino Di Carlo. Label-free collection of prostate circulating tumor cells using microfluidic Vortex technology. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4967.