Dr. Suzanne L. Topalian on Immunotherapy Biomarkers in CRC

Suzanne L. Topalian, MD, professor of Surgery, Johns Hopkins Medicine, discuses novel immunotherapy biomarkers in colorectal cancer (CRC).

Researchers are looking beyond PD-L1 expression as a biomarker for anti-PD-1 agents and instead considering how cancer genetics might play a role, says Topalian.

It is possible that there are genetic markers in the tumor that can help identify patients likely to respond to PD-1 agents.

One example of this can be seen in MSI-high (MSI-H) in CRC, says Topalian. CRC patients with defects in DNA mismatch repair mechanisms often have a high-mutational burden.

The MSI test is one test that is commonly used to determine if patients have this mismatch repair detect. These patients are very likely to respond to anti-PD-1 therapy, probably because all of the mutations in their tumors create new proteins that can be recognized by a very risk immune response.