Fig. 2

Immunoaffinity-based techniques where the EpCAM antigen is typically targeted on the surface of CTCs for positive enrichment, while the CD45 antigen is targeted on the surface of noncancerous cells for negative enrichment. For positive enrichment, only a subpopulation with a distinct antigen is captured. For negative enrichment, the obtained cancer cells are label-free, and a heterogeneous CTC population is obtained