HER2 Expression in Circulating Tumour Cells Isolated from Metastatic Breast Cancer Patients Using a Size-Based Microfluidic Device

Abstract

HER2 is a prognostic and predictive biomarker in breast cancer, normally assessed in tumour biopsy and used to guide treatment choices. Circulating tumour cells (CTCs) escape the primary tumour and enter the bloodstream, exhibiting great metastatic potential and representing a real-time snapshot of the tumour burden. Liquid biopsy offers the unique opportunity for low invasive sampling in cancer patients and holds the potential to provide valuable information for the clinical management of cancer patients. This study assesses the performance of the RUBYchip™, a microfluidic system for CTC capture based on cell size and deformability, and compares it with the only FDA-approved technology for CTC enumeration, CellSearch®. After optimising device performance, 30 whole blood samples from metastatic breast cancer patients were processed with both technologies. The expression of HER2 was assessed in isolated CTCs and compared to tissue biopsy. Results show that the RUBYchipTM was able to isolate CTCs with higher efficiency than CellSearch®, up to 10 times more, averaging all samples. An accurate evaluation of different CTC subpopulations, including HER2+ CTCs, was provided. Liquid biopsy through the use of the RUBYchipTM in the clinic can overcome the limitations of histological testing and evaluate HER2 status in patients in real-time, helping to tailor treatment during disease evolution.

The Role of Dielectrophoresis for Cancer Diagnosis and Prognosis

“…CTC enumeration is clinically relevant since it is associated with high tumor burden, aggressive disease, and inferior progression-free survival [ 107 , 108 , 113 ]. However, tag-based techniques for CTC enumeration and isolation can underestimate the amount of CTCs due to the loss of cells without epithelial markers [ 114 ]. Post-CTC recovery processing to detect either phenotype such as next-generation multidimensional flow cytometry, imaging, transcriptomics, metabolomics and proteomics, or genotype aberrations (such as ASO-RQ PCR, digital droplet PCR, and NGS that can reach 10-6 sensitivity, and their standardization among different laboratories, to investigate, at the single-cell level, novel biological mechanisms associated with cancer metastasis and tissue homing [ 115 , 116 , 117 , 118 , 119 ].…”

“…CTC enumeration is clinically relevant since it is associated with high tumor burden, aggressive disease, and inferior progression-free survival [ 107 , 108 , 113 ]. However, tag-based techniques for CTC enumeration and isolation can underestimate the amount of CTCs due to the loss of cells without epithelial markers [ 114 ].…”

Discriminating Epithelial to Mesenchymal Transition Phenotypes in Circulating Tumor Cells Isolated from Advanced Gastrointestinal Cancer Patients

“…Briefly, RUBYchip™ is a microfluidic device able to process 7.5 mL of whole blood. As previously described [34], it first separates the sample into two principal areas, each containing four separated modules. Each module features a single row of anisotropic micropillars interspaced 5 µm, comprising the cell filtering area.…”

“…Both the device and the well-plate were scanned using a fluorescence microscope (Nikon Eclipse Ti-E microscope, Nikon, Amsterdam, Netherlands) and Hoechst-positive cells were counted to determine the number of trapped cells inside the device and the total number of spiked cells. Capture efficiency was calculated as the number of trapped cells over the total number of target cells spiked into the initial whole blood sample, as already described [34].…”

“…Our research group has previously developed and validated microfluidic systems for the efficient and rapid isolation of unfixed CTCs, the later being the RUBYchip™. These systems have been demonstrated to capture CTCs based on their size and deformability directly from a whole blood sample in different cancer types, including colorectal, breast and bladder cancer [31][32][33][34]. In this work, using this microfluidic device, we were able to efficiently isolate CTCs in all samples from 11 advanced GI cancer patients and to classify them according to their expression of cytokeratin (CK) and Vimentin (VIM).…”