Dr. Bekaii-Saab on Resistance to Targeted Therapy in CRC

Tanios Bekaii-Saab, MD, professor of medicine, Mayo Clinic, discusses resistance to targeted therapy in the treatment of patients with colorectal cancer (CRC).

The development of targeted agents is gradually transforming the way physicians treat CRC, but resistance is still an obstacle. Patients can have primary resistance, which means they simply do not respond to the therapy, or acquired resistance, which means their disease progresses over time. Researchers understand that a patient’s disease might have driver mutations in addition to the one being targeted, and these other mutations can slowly become the primary driver.

A challenge that oncologists face in understanding mechanisms of resistance is that it requires additional tissue biopsies. This is a costly and invasive procedure, and Bekaii-Saab notes that it isn’t feasible to do this multiple times. This is easier to accomplish on small studies, but becomes more difficult when studies increase in size or with patients in the clinic. To potentially overcome this, investigators are conducting a large, multicenter study looking at the clinical utility of liquid biopsies and circulating-free DNA testing.