Dr. Strickler on the Value of Liquid Biopsies in CRC

John Strickler, MD, assistant professor of medicine, Duke University School of Medicine, gastrointestinal oncologist, Duke Cancer Institute, discusses the value of liquid biopsies in the treatment of patients with colorectal cancer (CRC).

Patients who are treated with targeted therapy will eventually develop resistance to those drugs. As such, acquired resistance to anti-EGFR therapy is commonly seen among patients with CRC, says Strickler. However, cell-free DNA or liquid biopsies can be used to help clinicians understand the genomic drivers of acquired resistance to these anti-EGFR antibodies.

There are several common mechanisms of resistance, including KRAS and NRAS as well as EGFR ectodomain mutations, which affect antibody binding. There are also alterations such as MET amplification. These alterations are most likely present in very low quantities in tumor tissue prior to receiving anti-EGFR therapy, notes Strickler. They will then expand under selective pressure as a result of conferred resistance to the antibody. With routine blood draws, physicians can identify those mutations and select appropriate treatment.