Circulating tumor DNA (ctDNA) utilizing a high-sensitivity panel to detect minimal residual disease post liver hepatectomy and predict disease recurrence.

Abstract

3522 Background: Preliminary data suggests that ctDNA can serve as a marker of minimal residual disease following colorectal cancer (CRC) tumor resection. Applicability of current ctDNA testing is limited by the requirement of sequencing known individual tumor mutations. We explored the applicability of a multi-gene panel ctDNA detection technology in CRC. Methods: Plasma was prospectively collected from CRC patients (pts) undergoing hepatic resections with curative intent between 1/2013 to 9/2016. In a blinded manner 5ml of preoperative (preop) and immediate post-operative (postop) plasma were tested using a novel 30kb ctDNA digital sequencing panel (Guardant Health) covering SNVs in 21 genes and indels in 9 genes based on the landscape of genomic alterations in ctDNA from over 10,000 advanced cancer pts with a high theoretical sensitivity (96%) for CRC. Median unique molecule coverage for this study is 9000 for cfDNA inputs ranging from 10 – 150 ng (media input preop = 27 ng, median input postop = 49 ng) with 120,000X sequencing depth on an IIlumina HiSeq2500. Results: A total of 54 pts underwent liver metastectomies with curative intent with a median follow-up of 33 months. Preop blood was a median of 49 days from last systemic chemotherapy and 3 days prior to surgery; postop blood was a median of 17 days after resection. Tumor mutations from standard of care hotspot multigene panel testing (at MDACC) were identified in 46 of 54 pts (85%). Preop ctDNA mutation detection rate was 80% (43/54) and 44% (24/54) in postop setting, with postop median allele frequency of 0.16% (range 0.01% to 20%). In pts with a minimum of 1 year follow up, sensitivity of postop ctDNA for residual disease was 58% (95%CI; 41%-74%), and specificity was 100% (66%-100%). In 43 patients who underwent successful resection of all visible disease, postop detection of ctDNA significantly correlated with RFS (P = 0.002, HR 3.1; 95% CI 1.7-9.1) with 2-year RFS of 0% vs. 47%. Recurrence was detected in ctDNA a median of 5.1 months prior to radiographic recurrence. Conclusions: The detection of postop ctDNA using an NGS panel-based approach is feasible and is associated with a very high rate of disease recurrence.

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).…”

Liquid Biopsy in Gastrointestinal Cancers

“…More recently, Yao et al noted RAS/BRAF mutation status in ctDNA as a prognosticator of poor progression free survival (PFS) in metastatic CRC patients treated with first line therapy, as has been well characterized in tumor genomic analysis [43,44]. These results reflect those of other studies examining the prognostic significance of detectable mutations in CRC ctDNA [35,37,43,45]. Circulating tumor DNA in CRC has also been shown to be effective in monitoring disease recurrence after completion of all treatments, further exemplifying its prognostic value.…”

“…Liquid biopsy as a tool for monitoring disease recurrence has also been well studied and the use of serial profiling has allowed for detection of recurrence up to 6 months before radiological imaging in CRC and pancreatic cancer patients [29,35,36]. For metastatic CRC, recent studies [34,35,37] demonstrate a decline and subsequent rise in ctDNA levels in response to chemotherapy and acquisition of resistance respectively, indicating that longitudinal monitoring of ctDNA may provide an alternative to the measurement of blood tumor markers, which often lack sensitivity and specificity [38]. Investigations on ctDNA for pancreatic cancer show similar findings, with changes in ctDNA corresponding closely with radiological imaging, CA19-9 levels, and recurrence [29,36].…”

RAS/BRAF Circulating Tumor DNA Mutations as a Predictor of Response to First-Line Chemotherapy in Metastatic Colorectal Cancer Patients

“…It was previously reported that, in patients who underwent complete surgical resection, postoperative detection of ctDNA significantly correlated with RFS ( P = 0.002, HR 3.1; 95% CI 1.7–9.1) and recurrence was detected in ctDNA a median of 5.1 months before radiographic recurrence [ 13 ]. In our study, we explored factors that might relate to recurrence after primary tumor resection.…”