Dr. Bekaii-Saab on the Impact of Next-Generation Sequencing in mCRC

Tanios Bekaii-Saab, MD, medical oncologist, Mayo Clinic, discusses the utility of next-generation sequencing in metastatic colorectal cancer (mCRC).

A couple of years ago, physicians would have likely said that genomic sequencing should be reserved for a select group of patients, says Bekaii-Saab. Now, every patient should get microsatellite instability (MSI) testing. Additionally, physicians now know that MSI is a surrogate biomarker for tumor mutational burden (TMB). All of these genomic platforms are showing that TMB has meaningful cutoffs, says Bekaii-Saab. Patients with high and potentially intermediate cutoffs respond to immunotherapy agents, whereas patients with low cutoffs do not. Now, TMB is being used to identify whether a patient should receive a PD-1 inhibitor or not.

For patients with KRAS and RAS mutations, testing is still limited, notes Bekaii-Saab, though identifying a BRAF mutation can help steer physicians toward the proper treatment. Physicians know that these patients have a worse prognosis with FOLFOX or FOLFOXIRI. Therefore, bevacizumab (Avastin) may be more suitable in the frontline setting.