Analysis of colorectal cancer‐related mutations by liquid biopsy: Utility of circulating cell‐free DNA and circulating tumor cells

Abstract

We recruited 56 colorectal cancer patients and compared the mutational spectrum of tumor tissue DNA, circulating cell‐free DNA (ccfDNA) and circulating tumor cell (CTC) DNA (ctcDNA) to evaluate the potential of liquid biopsy to detect heterogeneity of cancer. Tumor tissue DNA, ccfDNA, and ctcDNA were extracted from each patient and analyzed using next‐generation sequencing (NGS) and digital PCR. To maximize yields of CTC, three antibodies were used in the capture process. From 34 untreated patients, 53 mutations were detected in tumor tissue DNA using NGS. Forty‐seven mutations were detected in ccfDNA, including 20 not detected in tissues. Sixteen mutations were detected in ctcDNA, including five not detected in tissues. In 12 patients (35.3%), mutations not found in tumor tissues were detected by liquid biopsy: nine (26.5%) in ccfDNA only and three (8.8%) in ctcDNA only. Combination analysis of the two liquid biopsy samples increased the sensitivity to detect heterogeneity. From 22 stage IV patients with RAS mutations in their primary tumors, RAS mutations were detected in 14 (63.6%) ccfDNA and in eight (36.4%) ctcDNA using digital PCR. Mutations not detected in primary tumors can be identified in ccfDNA and in ctcDNA, indicating the potential of liquid biopsy in complementing gene analysis. Combination analysis improves sensitivity. Sensitivity to detect cancer‐specific mutations is higher in ccfDNA compared with ctcDNA.

Current status of ctDNA in precision oncology for hepatocellular carcinoma

“…To select the most appropriate mutation profiling specimens guiding clinical-decision making, it is necessary to perform a comparative study of CTC-derived DNA (CTC-DNA), ctDNA, and tumor tissue DNA (tumor DNA; Table 4). Sundaresan et al [148,149] believe the overall performance of ctDNA is superior to CTCs, but there is still a 20-30% blank that needs to be covered by combination analysis of ctDNA and CTC-DNA in non-small-cell lung cancer, a finding also corroborated in colorectal cancer [150], thoracic cancer [151], metastatic prostate cancer [152], and HCC [153].…”

Fractionated small cell‐free DNA increases possibility to detect cancer‐related gene mutations in advanced colorectal cancer

“…Results of this study indicate that the fractionation of cfDNA from CRC patients offers sensitive genetic detection by dPCR and NGS analysis, which would provide a less-invasive method to obtain the genetic tumor profiles. The sensitivity of cfDNA in detecting tumor mutations is currently reported to be 51-97% with digital PCR (dPCR) 13,18,19,[24][25][26][27]39 and 35-86% with NGS. 19,22,23,28,40,41 In our study, the sensitivity in detecting mutations in cfDNA from serum using dPCR was 85% and 93% when cut-off values of MAFs were set at >0% and >0.1%, respectively.…”

Updates on Clinical Use of Liquid Biopsy in Colorectal Cancer Screening, Diagnosis, Follow-Up, and Treatment Guidance

“…Circulating tumor DNAs are DNA fragments found in the bloodstream following different events, such as apoptosis, necrosis, and macrophage digestion. Some of them derive from malignant tumor cells, thus providing information about specific mutations in cancer (Takeda et al, 2019). In 1948, Mandel et al were the first who hinted at the occurrence of circulating free-DNA (cfDNA) in plasma from different diseases.…”