Circulating tumour cells (CTCs) are tumour cells that have separated from the primary tumour or metastasis and entered the bloodstream. CTCs have shown to be promising diagnostic and prognostic biomarkers for several different cancers. Numerous approaches for detecting CTCs in the peripheral blood are available, including both marker-dependent and marker-independent techniques. This study aimed to optimize and evaluate a marker-independent, size-based method for the enrichment of CTCs from patients with metastatic breast cancer.
The breast cancer cell lines MCF-7 and ZR-75-1 spiked into blood from healthy volunteers were used as a model system for the validation of the VYCAP size-based filtration technology. The cells were stained with immunofluorescently labelled antibodies, and microscopy was used to validate the results of the staining and to enumerate the cells. Optimization of the method was done by testing different blood collection tubes, as well as fixation and permeabilization reagents. The TransFix blood collection tube, in combination with the FIX&PERM cell fixation and permeabilization kit, were determined to be optimal for this procedure.
CTCs were isolated from patients with metastatic breast cancer using the VYCAP size-based filtration system. Analysis of 7 patient blood samples detected CTCs and CTC clusters in only 1/7 (14%) of the samples.
In conclusion, optimal conditions for cell line cells were established, and cells were isolated with high recovery rates. Still, clinical validation of the size-based enrichment technique requires further investigation. More patient samples are necessary to assess clinical relevance.