Abstract:

Objective

The aim of this study was to establish an efficient circulating tumor cells（CTC） sorting system for colorectal cancer and to investigate the feasibility of CTC instead of tumor tissue for gene mutation detection.

Methods

The CTC sorting system modified by EpCAM and Vimentin antibody was established. The sorting efficiency of the CTC sorting system on colorectal cancer cells was detected by cellular experiments， and CTC from 30 colorectal cancer patients were captured and counted. The hotspot mutated genes in patient tumor tissue samples were detected by NGS， and the hotspot mutated genes in blood CTC were detected by Sanger sequencing， and the consistency of hotspot gene mutations between tumor tissues and blood CTC was analyzed.

Results

The CTC sorting system constructed in this study had good dispersion， stability and low cytotoxicity， with a specificity of 90.54% and a sensitivity of 89.07%.The mean number of CTC in the blood of colorectal cancer patients was （10.90±5.11）/7.5 mL. The highfrequency mutated genes （TP53， KRAS， EGFR， BRAF， APC， PIK3CA） detected by CTC were all in high concordance with the tissue assay， and the overall mutation concordance rate for all the genes was （92.89±4.89）%.

Conclusions

The CTC sorting system based on sequential enrichment of Ep-LMB/Vi-LMB is capable of efficiently capturing CTC from peripheral blood of colorectal cancer patients. Using the captured CTC for hotspot mutation detection in the clinic solves the problem of difficult tumor tissue sampling to a certain extent， which is of great clinical significance.

Key words: Colorectal neoplasms, Circulating tumor cells, Gene mutation, Next-generation sequencing, Consistency