On April 30, 2021 Guardant Health reported that For patients with early-stage colorectal cancer (CRC), the presence of circulating tumor DNA (ctDNA) or minimal residual disease (MRD) after curative intent treatment is becoming an important prognostic biomarker for cancer recurrence, and can also be used to evaluate the potential need for adjuvant treatment in post-surgical patients (Press release, Guardant Health, APR 30, 2021, View Source [SID1234578903]). Until recently, tests developed to detect MRD required tumor tissue to gain the necessary genomic information needed to accurately identify high-risk patients. A new study led by Massachusetts General Hospital Cancer Center and published in Clinical Cancer Research demonstrates that Guardant Reveal, the first blood-only liquid biopsy to identify MRD, identifies those patients most likely to recur, with industry-leading sensitivity, without the need for tumor tissue.1,2

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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.

"The integration of cancer-specific epigenomic and genomic signatures allows Guardant Reveal to detect minimal residual disease in early-stage colorectal cancers with industry-leading performance and without the need for tumor tissue," said AmirAli Talasaz, Guardant Health president. "We believe that Guardant Reveal can be a powerful decision-making tool for oncologists managing patients with early-stage colorectal cancer. In addition, our blood-only approach offers a more streamlined workflow and faster turnaround time for clinical decision making."

"By detecting minimal residual disease after curative intent treatment, we can have a better understanding of which patients are at high-risk for recurrence and perhaps tailor additional therapy," said Aparna Parikh, MD, MPH, Gastrointestinal Oncologist at Massachusetts General Hospital and Assistant Professor of Medicine, Harvard Medical School. "This study demonstrates that the incorporation of epigenomic signatures with genomic alterations allows for Guardant Reveal to have comparable sensitivity and specificity as tumor informed approaches, but without the need for tumor tissue."

Tissue-dependent MRD tests have previously reported sensitivities of 40%-50% with a single post-surgical blood draw.1,3 When looking only at the subset of patients with stage II or III CRC in this study, Guardant Reveal had a sensitivity of 63% and a specificity of 100% for recurrence. These data show that Guardant Reveal can detect minimal residual disease from a simple blood draw. In addition, the sensitivity of the test increases with additional longitudinal blood draws, allowing for earlier detection of recurrence in the patient surveillance setting compared with standard imaging methods.

The Guardant Reveal test achieves industry-leading sensitivity (91%)2 for detecting ctDNA by simultaneously interrogating genomic and epigenomic alterations. The test accurately identifies genomic alterations down to allele frequencies of 0.01% and effectively filters out biological noise sources such as mutations caused by clonal hematopoiesis. The incorporation of biologically relevant epigenomic signatures is essential to increasing test sensitivity in the post curative intent and surveillance patient populations.

The publication titled, "Minimal Residual Disease Detection using a Plasma-Only Circulating Tumor DNA Assay in Colorectal Cancer Patients" can be found here.