One of the most important features in a stage four metastatic colorectal setting is knowing the status of something that can tell you whether you’ll respond well to immune therapy or not. If you have a problem with your mismatch repair proteins, or basically it’s called DMMR, you’re deficient in your mismatch repair, that means you could potentially, and likely will be sensitive to immune therapy.
Other terms for this are MSI high, which is microsatellite instability, or, with some immune therapies, they look at tumor mutational burden or CPS, which is a combined score. So if you’re looking at other tumors, these, all these terms, MMR, MSI, TMB, CPS, PD-L1, they all relate to immune therapy. In colorectal cancer, if you are deficient in MMR, you qualify for immune therapy, either by itself or combination immune therapy as a dual regimen once you failed cytotoxic chemotherapy. We do not go straight to immune therapy in a stage four setting traditionally. We usually do the previous agents we talked about, FOLFOX, FOLFIRI, but then after you progress on these backbone cytotoxic agents, your qualification for immune therapy are based on these terms. And it is very important for you and your oncologist to know where your tumor stands in relation to these terms.