Abstract 2374: Performance of a new generation antibody-independent ApoStream™ platform for the enrichment of circulating tumor cells (CTCs)
Authors: Vishal Gupta, Insiya Jafferji, Miguel Garza, Vladislava O. Melnikova, Dave Hasegawa, Darren W. Davis
Journal: Cancer Research (2012)

Abstract Background: Isolation and molecular analysis of Circulating Tumor Cells (CTCs) is technically challenging, but may replace tumor biopsy by providing a minimally-invasive, blood-based, “liquid biopsy” method to monitor metastatic disease progression and guide cancer therapy. The use of currently available EpCAM-based enrichment platforms limits the type of tumor cells that can be recovered. We have developed the first robust CTC isolation device, ApoStream™, which does not rely on specific surface proteins or the size of CTCs. Specific Aims: We demonstrate the performance of a novel antibody-independent dielectrophoretic field-flow fractionation (DEP-FFF) based CTC isolation platform: ApoStream™. Methods: In the ApoStream™ device, DEP-FFF is used to differentially drive cell movement based on different biophysical properties of cells in a continuous flow microfluidic chamber to isolate CTCs from peripheral blood mononuclear cells (PBMCs). To demonstrate performance, pre-labeled SKOV3 ovarian cancer cells (low EpCAM expressing) were spiked into buffer or PBMCs and isolated through ApoStream™ device. Cancer cell recovery, system linearity, and precision were demonstrated. Viability of cancer cells isolated through the ApoStream™ platform, as well as their ability to be propagated in culture, was confirmed. Results: On three different days, the ApoStream™ breadboard device recovered 83.0± 3.0% (mean ± SD), 76.3 ± 2.6%, and 81.5± 1.0% of SKOV3 cells spiked into buffer (average interday recovery of 80.3 ± 3.5%, CV% = 4.3). Additionally, 79.0 ± 1.5%, 81.2 ± 7.8% and 75.2 ± 4.3% of SKOV3 cells spiked into ∼10 million normal PBMCs (average interday recovery 78.5 ± 3.0%, CV% = 3.3) were recovered. When SKOV3 spiking recovery was measured on two different ApoStream™ devices, the CV% was 0.1%. System linearity was evaluated by spiking a range of 4 - 2,600 SKOV3 cells into 10 million PBMCs. The regression analysis for the linearity resulted in a correlation coefficient (R2) of 1.00. Cell viability was not affected by the ApoStream™ device, and was 98.2, 98.8 and 100% of initial viability at 0, 16 and 24 hours after ApoStream™ separation, respectively, as measured by Trypan blue exclusion test conducted on cells propagated in tissue culture. Conclusion: We developed the first antigen-independent and cell size independent device for isolation of CTCs from patient blood with a wide variety of cancers. ApoStream™ technology performance characterization demonstrated high recovery of EpCAM-negative cultured cancer cells over a significant range of spiked cell numbers, as well as excellent linearity performance. Isolation of large numbers of live and unfixed CTCs with the ApoStream™ platform enables downstream molecular characterization of CTCs for the development of personalized treatment options for cancer patients. Acknowledgments: Funded by NCI Contract No. HHSN261200800001E. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2374. doi:1538-7445.AM2012-2374