Analytical performance of the FDA-cleared Parsortix® PC1 system

Abstract

Introduction: The Parsortix^® PC1 system, Food and Drug Administration (FDA) cleared for use in metastatic breast cancer (MBC) patients, is an epitope-independent microfluidic device for the capture and harvest of circulating tumor cells from whole blood based on cell size and deformability. This report details the analytical characterization of linearity, detection limit, precision, and reproducibility for this device.

Methods: System performance was determined using K₂-EDTA blood samples collected from self-declared healthy female volunteers (HVs) and MBC patients spiked with prelabeled cultured breast cancer cell lines (SKBR3, MCF7, or Hs578T). Samples were processed on Parsortix^® PC1 systems and captured cells were harvested and enumerated.

Results: The system captured and harvested live SKBR3, MCF7, and Hs578T cells and fixed SKBR3 cells linearly between 2 and ~100 cells, with average harvest rates of 69%, 73%, 79%, and 90%, respectively. To harvest ≥1 cell ≥95% of the time, the system required 3, 5 or 4 live SKBR3, MCF7 or Hs578T cells, respectively. Average harvest rates from precision studies using 5, 10, and ~50 live cells spiked into blood for each cell line ranged from 63.5% to 76.2%, with repeatability and reproducibility percent coefficient of variation (%CV) estimates ranging from 12.3% to 32.4% and 13.3% to 34.1%, respectively. Average harvest rates using ~20 fixed SKBR3 cells spiked into HV and MBC patient blood samples were 75.0% ± 16.1% (%CV = 22.3%) and 68.4% ± 14.3% (%CV = 21.1%), respectively.

Conclusions: These evaluations demonstrate the Parsortix^® PC1 system linearly and reproducibly harvests tumor cells from blood over a range of 1 to ~100 cells.

Keywords: Blood; Breast cancer; Circulating tumor cells; Liquid biopsy; Microfluidic devices; Neoplastic cells.

Fig. 1 -

Parsortix^® PC1 system observed linearity when processing blood samples spiked with a range of cell numbers for live SKBR3, MCF7, and Hs578T cells and fixed SKBR3 cells. Linear (first-order polynomial) regression analysis indicated in black, second-order polynomial regression analysis indicated in blue, and third-order polynomial regression analysis indicated in orange. (A) Live SKBR3 harvest linearity for between 2 and ~100 cells spiked into 7.5 mL of blood, with first-, second-, and third-order polynomial regression analyses shown (34). (B) Fixed SKBR3 harvest linearity for between 2 and ~100 cells spiked into 7.5 mL of blood, with first-, second-, and third-order polynomial regression analyses shown. (C) Live MCF7 harvest linearity for between 2 and ~100 cells spiked into 7.5 mL of blood, with first-, second-, and third-order polynomial regression analyses shown (34). (D) Live Hs578T harvest linearity for between 2 and ~100 cells spiked into 7.5 mL of blood, with first-, second-, and third-order polynomial regression analyses shown (34). (E) Live SKBR3 harvest linearity for between 2 and ~1,000 cells spiked into 7.5 mL of blood, with first-, second-, and third-order polynomial regression analyses shown.

Fig. 2 -

Parsortix^® PC1 system limit of detection. Percent of replicates with ≥1 cell harvested when blood was spiked with 1, 2, 3, 4, or 5 live SKBR3, MCF7, or Hs578T cells. Note: For the SKBR3 and Hs578T cell lines, the 5-cell spike level was not evaluated as both of these cell lines showed recoveries of >1 cell at lower cell spike levels.

Fig. 3 -

Precision of the Parsortix^® PC1 system. Percent harvest (average and 95% CI shown) when spiking ~20 fixed SKBR3 cells into 2.5 mL PBS at different laboratory sites (MDA, URMC, ANGLE R&D) and using different separation cassette lots (Lot G, Lot C, and Lot F) or spiking ~20 fixed SKBR3 into 10 mL of blood, or ~20 live SKBR3 cells into 7.5 mL of blood. CI = confidence interval; PBS = phosphate-buffered saline.

Fig. 4 -

Reproducibility of the Parsortix^® PC1 system. Percent harvest results from HV subject and MBC patient blood samples (≥5 mL of blood from a 10 mL K₂-EDTA tube) spiked with ~20 fixed, prelabeled SKBR3 cells. EDTA = ethylenediaminetetraacetic acid; HV = healthy female volunteer; MBC = metastatic breast cancer.