Application of CAPTURE Assay for Early Diagnosis and Prognosis in Bile and Blood of Cholangiocarcinoma

PURPOSE Cholangiocarcinoma (CCA) is highly metastatic, difficult to diagnose, and characterized by extremely low 5-year survival rate. Liquid biopsy is reported as a new tool for monitoring and potential diagnosis of cancers. In this study, we developed a novel approach, CAPTURE (Cancer cell affinity probing and tracked by immunoreaction) assay, using blood and bile for the detection of CCA. MATERIALS AND METHODS The CAPTURE assay isolated exfoliated tumor cells (ETCs) from bile and circulating tumor cells (CTCs) from blood of patients with CCA (CCA+) using magnetic beads coated with two affinity probes: a nucleic-acid aptamer or a glycosaminoglycan octasaccharide, followed by immunostaining to track target tumor cells-bead complexes. Target-bead complexes were quantified under a fluorescent microscope (ETCs: CK17+/CK7+/Hoechst+; CTCs: CK17+/CD45-/Hoechst+). Epithelial cell adhesion molecule was also used as a comparison. The blood and bile from patients of benign biliary-related diseases (CCA-) served as control. The study was validated in a single-blind fashion. RESULTS Finally, numbers of CTCs of blood (82 CCA+ and 48 CCA-) and ETCs of bile (132 CCA+ and 63 CCA-) samples were quantified and validated. Sensitivities and specificities were 98.5% and 85.7% with bile tests, and 96.3% and 85.4% with blood tests. Moreover, we successfully monitored prognoses of two follow-up patients using CAPTURE assay after treatments. CONCLUSION ETCs in bile could be promising indicators of disease status in early through advanced stages of CCA, whereas CTCs in blood might have crucial value in diagnosing and monitoring advanced stages of CCA. Our results showed that the CAPTURE assay would be a powerful tool in CCA diagnostics and prognostics.