Experts have used circulating tumor DNA (ctDNA) concentration to detect molecular residual disease (MRD) in patients with early-stage and advanced colorectal cancer (CRC), according to real-world study data being presented at the virtual 2020 ASCO Annual Meeting.

“ctDNA testing can be used for the assessment of MRD in patients with early-stage or advanced CRC. Prospective evaluation of this methodology in clinical practice has been limited to-date,” wrote Pashtoon Murtaza Kasi, MD, MS, Mayo Clinic, Jacksonville, Florida, and co-investigators.

Thus, seeking to detect and quantify ctDNA for MRD assessment, Dr Kasi et al used a personalized and tumor-informed multiplex PCR assay (ie, Signatera 16-plex bespoke mPCR NGS assay) in 250 patients with gastrointestinal cancers.

The purpose was to evaluate an ongoing early adopter program of ctDNA testing across the spectrum of CRC management.

The study population was comprised of 200 patients with colon cancer, 40 with rectal cancer, and 10 with other lower gastrointestinal cancers (ie, anal, appendiceal, small bowel).

According to study findings, ctDNA detection was significantly tied to disease stage (P <.0001 Chi-square, 70.33), and yielded a 100% detection rate in patients with radiologically measurable active metastatic disease.

By contrast, the investigators observed ctDNA positivity rates of 28.5% and 19.2% in patients with advanced/metastatic disease who had partial response to treatment or no evidence of disease, respectively.

“This is the first large, real-world study reporting on the results from a clinically validated MRD assay. For the first time we delineate MRD rates and quantify ctDNA concentration in patients with early-stage and advanced CRC,” Dr Kasi and colleagues wrote.

“Furthermore, we provide an initial readout that effective ongoing treatment in patients with CRC may be correlated with ctDNA clearance,” they concluded.—Hina M. Porcelli

Kasi PM, Dayyani F, Morris VK, et al. Tumor-informed assessment of molecular residual disease and its incorporation into practice for patients with early and advanced-stage colorectal cancer (CRC-MRD Consortia). Presented at: the 2020 ASCO Annual Meeting; May 29-31, 2020. Abstract 4108.