Early prediction of clinical outcomes in resected stage II and III colorectal cancer (CRC) through deep sequencing of circulating tumor DNA (ctDNA).

Abstract

3591 Background: Adjuvant chemotherapy is offered to most pts with Stage III CRC, and to a subset with Stage II disease deemed at high-risk for recurrence. Nevertheless, risk stratification strategies remain suboptimal. Detection of minimal residual disease (MRD) through ctDNA analysis has been shown to identify pts at high recurrence risk in Stage II CRC, but not Stage III disease. Methods: The next-generation sequencing based AVENIO ctDNA Surveillance Kit (Research Use Only) was used to identify single nucleotide variants (SNVs) in tumor tissue within a cohort of 145 Stage II and III CRC pts following R0 surgical resection (n = 86 and 59 respectively; median follow-up = 32.1 mo). The same assay was used to monitor ctDNA with a single post-operative blood sample (mean surgery-to-phlebotomy time: 10 days). Regions from 197 genes recurrently mutated in CRC were interrogated, and pts were classified as ctDNA positive (+) or negative (-) in plasma based on the detection of SNVs previously identified in tumor tissue. Results: Variants were identified in 99% of tumors (n = 144) with a median of 4 SNVs/sample (range 1-24) and all post-operative plasma samples were successfully profiled. Pts with detectable ctDNA (n = 12) displayed a significantly shorter 2-year relapse-free survival (RFS; 17% vs 88%; HR 10.3; 95% CI 2.3-46.9; p < 0.00001), time to recurrence (TTR; HR 20.6; 95% CI 3.1-139.0; p < 0.00001) and overall survival (OS; HR 3.4; 95% CI 0.5-25.8; p = 0.041) than ctDNA- pts (n = 132). 11 (92%) of ctDNA+ pts developed recurrence compared to 9 (7%) of ctDNA- pts. Monitoring multiple variants doubled sensitivity of MRD detection compared to tracking a single driver mutation. TTR was shorter in ctDNA+ vs ctDNA- Stage II (HR 23.1, 95% CI 0.28-1900.4; p < 0.00001) and stage III pts (HR 17.9; 95% CI 2.7-117.3, p < 0.00001). TTR of Stage II and III ctDNA- pts was similar (p = 0.7). Conclusions: Our results indicate that ctDNA analysis can detect MRD within days after complete resection of CRC and accurately identifies pts at high risk of recurrence in both Stage II and III CRC. MRD detection via ctDNA sequencing may allow personalization of adjuvant treatment strategies.

Molecular Residual Disease and Adjuvant Trial Design in Solid Tumors

“…Molecular Residual Disease (MRD). ctDNA has been shown in multiple tumor types to detect MRD, including nasopharyngeal carcinoma (27), colorectal carcinoma (28)(29)(30)(31)(32), locally advanced rectal carcinoma (33), breast carcinoma (34), pancreatic carcinoma (35,36), and lung carcinoma (37) ( Table 1). ctDNA in the plasma has a short half-life (<2 hours); however, it has been found that ctDNA may be elevated 24 hours following intervention in early post-operative samples, most likely due to release of ctDNA from damaged tissue (28).…”

ctDNA applications and integration in colorectal cancer: an NCI Colon and Rectal–Anal Task Forces whitepaper

“…The proportion of patients with colorectal cancer (CRC) in whom ctDNA can be detected depends on the extent of tumour volume and ranges from 50% in those with non-metastatic disease to nearly 90% in patients with metastatic disease 9 . In those who have undergone curative resection, earlier studies suggest that the postoperative detection of ctDNA ranges from 10-15% of patients with stage II disease to nearly 50% in those with stage IV disease [9][10][11][12][13][14][15][16] . Building on these studies, data on the potential uses of ctDNA are rapidly accumulating in the continuum of care across multiple cancers, including CRC (Fig.…”

Use of Circulating Tumour DNA to Assess Minimal Residual Disease in Gastrointestinal Cancers

“…While other tumour-informed assays using Safe-SeqS, ddPCR and other designs exist, the Signatera test has been widely studied in many GI and non-GI tumour types, demonstrating impressive sensitivities (88-100%) and specificities (93-100%) for MRD, positive predictive values for relapse (>98%) and median lead times from ctDNA detection to relapse (8-9 months). [20][21][22]24,29,34,36,50,[52][53][54][55][56][57][58][59][60][61][62][63][64][65] These highly specific and sensitive assays are particularly attractive for MRD detection and are being increasingly studied in this space. However, due to the inherent process of tumour, germline and then peripheral blood sequencing, tumour-informed testing may be more expensive than the plasma-only approach, as it first requires tumour tissue acquisition and testing, and takes longer to obtain results (4-6 weeks for the first and then 7-10 days for subsequent test results).…”