Serial Liquid Biopsies Allow for Tracking of Resistance Mutations in GI Cancers

Pashtoon M. Kasi, MBBS, MD, MS, clinical assistant professor of internal medicine, University of Iowa Carver College of Medicine, discusses how serial testing via liquid biopsies in patients with gastrointestinal cancers can provide oncologists with a better picture of the patient’s condition and potential acquired mechanisms of resistance. He explains that multiple liquid biopsies are especially helpful for the management of colorectal cancer when patients progress on anti-EGFRtherapies to identify and track potential acquiredRASmutations.

Kasi lead a study of 322 patients in which serial biopsies were conducted to monitor potential changes in each patient’s disease using the Guardant360 assay. In the study, researchers were able to identifyRAS/RAFwild type(n = 214),RASmutations (n = 83),BRAF V600E mutations(n = 18), non—BRAFV600Emutations (n = 7),HER2amplifications (n = 13),HER2mutations (n = 7), and microsatellite instability—high (n = 3). Recognizing these alterations helped with treatment modification and clinical trial selection for these patients.