Cell-free DNA (cfDNA)-based detection of microsatellite instability (MSI) status was found to be highly concordant with tissue-based MSI testing, according to results of an analysis recently published in Clinical Cancer Research
Findings showed that incorporating MSI detection into the 74-gene panel liquid biopsy assay Guardant360 demonstrated high concordance in approximately 1145 cfDNA samples for which MSI status based on standard tissue testing was.
The National Comprehensive Cancer Network’s clinical practice guidelines recommend MSI as a biomarker in at least 9 malignancies: esophageal/esophagogastric cancer, cervical cancer, pancreatic cancer, ovarian cancer, colorectal cancer (CRC), prostate cancer, gastric cancer, cervical cancer, and cholangiocarcinoma.
MSI status is generally tested via standard tissue biopsy; yet, MSI testing is underutilized in clinical practice due to lack of viable tissue, the inherent invasive nature of tissue-based biopsies, and a lack of routine testing. If detected, MSI-high (MSI-H) status is a predictive marker to receive treatment with immunotherapy.
Currently, pembrolizumab (Keytruda) is approved for the treatment of adult and pediatric patients with unresectable or metastatic, MSI-H or mismatch repair deficient (dMMR) solid tumors that have progressed after prior treatment and who have no satisfactory alternative treatment options, as well as for patients with MSI-H or dMMR CRC following progression on a fluoropyrimidine, oxaliplatin, and irinotecan.
The combination of nivolumab (Opdivo) and ipilimumab (Yervoy) is also indicated for the treatment of adult and pediatric patients ≥12 years with MSI-H or dMMR metastatic…