VIDEO: Microsatellite instability predicts enhanced response to immunotherapy

A small subgroup of patients with colorectal cancer have demonstrated a “really remarkable benefit” from the “immunotherapy revolution,” according to J. Randolph Hecht, MD, professor of clinical medicine in the David Geffen School of Medicine at UCLA and director of the gastrointestinal oncology program at UCLA.

Patients with colorectal cancer and microsatellite instability respond “wonderfully” to immunotherapy agents, including PD-1 and PD-L1 inhibitors, although only 10% to 15% of patients with colorectal cancer have microsatellite instability, according to Hecht. Patients with a greater number of mutations have also demonstrated improved responses to immunotherapy, he said.

As a result, checking all patients with colorectal cancer for microsatellite instability enables the physician to plan treatment more effectively.

“As oncologists, we’re supposed to take family histories – but some of these patients don’t have strong family histories,” Hecht said. “By checking [for microsatellite instability] … you’re going to pick up patients that you can help, to make certain they don’t get a second cancer, and you can also help an entire family.”