Liquid biopsy in cancer patients: advances in capturing viable CTCs for functional studies using the EPISPOT assay

Expert Rev Mol Diagn. 2015;15(11):1411-7. doi: 10.1586/14737159.2015.1091729. Epub 2015 Sep 21.


Circulating tumor cells (CTCs) in the blood of cancer patients have received increasing attention as new diagnostic tool enabling 'liquid biopsies'. In contrast to the wealth of descriptive studies demonstrating the clinical relevance of CTCs as biomarkers, the extremely low concentration of CTCs in the peripheral blood of most cancer patients challenges further functional studies. This article discusses the current possibilities to enrich and, in particular, detect viable CTCs with emphasis on the EPithelial ImmunoSPOT technology. This functional assay detects viable CTCs at the single-cell level and has been used on hundreds of patients with different tumor types including epithelial tumors (breast, prostate and colon cancer) and melanomas. Moreover, the article summarizes recent advances in the in vitro and in vivo expansion of CTCs from cancer patients. These functional analyses will contribute to identifying the biological properties of metastatic cells and reveal new therapeutic targets against disseminating cancer cells.

Keywords: Circulating tumor cells; EPISPOT assay; Functional assay; Personalized medicine; Viability.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Biomarkers, Tumor
  • Biopsy
  • Cell Survival
  • Clinical Trials as Topic
  • Disease Models, Animal
  • Humans
  • Immunophenotyping / methods
  • Neoplasm, Residual / diagnosis
  • Neoplasms / diagnosis*
  • Neoplasms / metabolism
  • Neoplasms / pathology
  • Neoplasms / therapy
  • Neoplastic Cells, Circulating / metabolism
  • Neoplastic Cells, Circulating / pathology*
  • Prognosis
  • Treatment Outcome


  • Biomarkers, Tumor