New Research Points to a Better Biomarker for MSI Metastatic Colorectal Cancer

This transcript has been edited for clarity.

I'm David Kerr, professor of cancer medicine at the University of Oxford. I'd like to talk to you today about a really lovely paper published earlier this year in Annals of Oncology by an outstanding French group. As you know, we're very interested always in precision medicine and trying to improve how we match drugs to patients, their tumor genotype, their pharmacogenetics, and so on.

They've done a really nice piece of work looking at how we can identify patients who are likely to be more responsive to immune checkpoint inhibitors. The study included 110 patients with metastatic colorectal cancer who had been treated with programmed death-ligand 1 (PD-L1) inhibitors plus or minus a cytotoxic T-lymphocyte–associated protein 4 (CTLA-4) inhibitor. It's a reasonable cohort to study. They looked at DNA and RNA sequencing. They took a discovery-and-validation approach across this cohort.

What they found was really interesting. They looked at tools that we had considered to be reasonable markers of response, such as tumor mutational burden, other work that had been done taking a deeper dive into microsatellite insufficiency and infiltrating immune cells — things that seem very plausible in terms of identifying patients who would respond better to immune manipulation, if you like.