Novel Circulating Tumor Cell Assay for Detection of Colorectal Adenomas and Cancer

Abstract

Objectives: There is a significant unmet need for a blood test with adequate sensitivity to detect colorectal cancer (CRC) and adenomas. We describe a novel circulating tumor cell (CTC) platform to capture colorectal epithelial cells associated with CRC and adenomas.

Methods: Blood was collected from 667 Taiwanese adults from 2012 to 2018 before a colonoscopy. The study population included healthy control subjects, patients with adenomas, and those with stage I-IV CRC. CTCs were isolated from the blood using the CellMax platform. The isolated cells were enumerated, and an algorithm was used to determine the likelihood of detecting adenoma or CRC. Nominal and ordinal logistic regression demonstrated that CTC counts could identify adenomas and CRC, including CRC stage.

Results: The CellMax test demonstrated a significant association between CTC counts and worsening disease status (Cuzick's P value < 0.0001) with respect to the adenoma-carcinoma sequence. The test showed high specificity (86%) and sensitivity across all CRC stages (95%) and adenomatous lesions (79%). The area under the curve was 0.940 and 0.868 for the detection of CRC and adenomas, respectively.

Discussion: The blood-based CTC platform demonstrated high sensitivity in detecting adenomas and CRC, as well as reasonable specificity in an enriched symptomatic patient population.

Translational impact: If these results are reproduced in an average risk population, this test has the potential to prevent CRC by improving patient compliance and detecting precancerous adenomas, eventually reducing CRC mortality.

Figure 1.

CMx CTC platform assay workflow including sample collection, cell enrichment, staining, imaging, and analysis. CMx, CellMax; CTC, circulating tumor cell.

Figure 2.

CTCs (a–d) isolated from patients with CRC. Images taken with Leica DM6B microscope with 10× objective (red, CK20; green, CD45; blue, DAPI). CRC, colorectal cancer; CTC, circulating tumor cell; DAPI, 4', 6-diamidino-2-phenylindole.

Figure 3.

CTCs (a–d) isolated from patients with colorectal adenomas. Images taken with Leica DM6B microscope with 10× objective (red, CK20; green, CD45; blue, DAPI). CTC, circulating tumor cell; DAPI, 4', 6-diamidino-2-phenylindole.

Figure 4.

Plot of mean CTC count ± standard error of the mean vs CRC (CTC) stage. Based on mean CTC counts, healthy subjects (2.11 CTCs) could be distinguished from patients with adenomas (5.83 CTCs; P < 0.0001) or CRC (16.99 CTCs; P < 0.0001). Mean CTC counts for subjects with late-stage CRC (III–IV; >22 CTCs) were also significantly different from mean CTC counts for subjects with early stage-I CRC (6.0 CTCs; P = 0.015) as well as adenomas (5.8 CTCs; P = 0.016). CRC, colorectal cancer; CTC, circulating tumor cell.

Figure 5.

ROC curve comparison for CRC and adenomas. CRC, colorectal cancer; ROC, receiver operating characteristic.