Most downstream applications (NGS, PCR, etc.) work better when there are fewer background cells (WBCs) in the enrichment fraction. One of the principle benefits of the IsoFlux System is the reduction in WBC carryover as compared to conventional approaches (e.g. magnetic bead enrichment, CellSearch, filters, etc.).
Fluxion is continuing to innovate ways to increase the sample purity. One method that we have tested recently is to increase the starting blood volume. While patient blood is generally in limited supply for research purposes, in many cases it is possible to receive two or more blood tubes. We wanted to compare the resulting purity (# of target cells / # total cells X 100%) if we ran one blood tube (7mL) versus two tubes (14mL) on the same IsoFlux cartridge.
The results were compelling...
150 MDA-MB-231 cells (a low EpCAM expressing breast cancer cell line) were spiked in per 7mL of blood, in starting volumes of 7mL (150 total cells) and 14mL (300 total cells). Total recovery was nearly double in the 14mL sample (97 cells versus 200 cells), yet the background level of WBCs only increased slightly. Resulting purity in the 14mL sample was 50% higher.
This approach provides two key benefits....
1) An increase in circulating tumor cell (CTC) purity will improve the overall robustness and sensitivity of the downstream analysis for applications such as NGS, qPCR, dPCR, etc.
2) Likewise, an increase in the total number of circulating tumor cells will improve robustness of the downstream assay and increase the total percentage of the patient population that can be analyzed.