RE: Question29 Jan 2021 12:14
moonparty,
When it comes to the utility of Parsortix versus antibody based CTC liquid biopsy systems, Parsortix has a major advantage in it's ability to capture both epithelial and mesenchymal cells. I'm not sure this is fully appreciated and will have a go at explaining, but please feel free to ignore if it's too much detail or I'm teaching you to suck eggs.
Antibody based systems like CellSearch work by seeking out and capturing cells displaying the specific marker EpCAM which is a molecule expressed on epithelial cells. However, cancer cells can undergo a process called EMT (epithelial-to-mesenchymal transition) whereby they lose their epithelial characteristics and become purely purely mesenchymal . So whilst the antibody based systems can pick up epithelial cells, as they undergo EMT they'll pick up less and less as they stop displaying the EpCAM marker and once they become purely mesenchymal cells they'll miss them altogether. A good example is in prostate cancer where CellSearch fails to pick up any CTCs at all in about a third of patients - it's believed that this is due to the fact that it can't detect cells undergoing EMT. Parsortix on the other hand doesn't differentiate and can pick up both epithelial and mesenchymal cells.
This is really important from a clinical point of view because EMT is associated with a particularly poor prognosis, with increased shedding of CTCs which are more likely to lead to metastasis . So you can see that if you wanted to carry out any downstream analysis, you'd definitely want to be buying a system that picks up mesenchymal cells, otherwise you're only seeing half the picture.