The single-center, prospective study evaluated the effectiveness of the Guardant Reveal liquid biopsy test to detect MRD in patients with stage I-IV colorectal cancer after curative intent therapy. Blood draws were taken one month after completion of definitive treatment, either surgery or adjuvant therapy, and at various surveillance or monitoring timepoints. Blood samples were analyzed using the Guardant Reveal test, which integrates both cancer-specific epigenomic signatures and genomic alterations, unlike standard MRD tests which analyze only genomic alterations.
In the primary landmark analysis (n=84), blood samples were taken from the curative intent patient population one month (median 31.5 days) after completion of definitive treatment. In the subset of patients with at least one year of clinical follow-up, all patients with detectable ctDNA recurred (100% PPV). Guardant Reveal test sensitivity and specificity were 55.6% and 100% respectively for this single timepoint. By incorporating longitudinal surveillance samples, sensitivity improved to 91%. Integrating epigenomic signatures increased test sensitivity by 36% versus using genomic alterations alone. Additionally, CEA tests, the traditional biomarker for colorectal cancer, did not predict recurrence in this patient cohort.