A. David McCollum, MD, Baylor-Sammons Cancer Center, discusses integrating immunotherapy into the treatment landscape of colorectal cancer (CRC).
According to McCollum, patients who have microsatellite instability-high (MSI-H) phenotype or a mismatch-repair deficient immunohistochemistry profile seem to be the patients who derive the most benefit from PD-1/PD-L1 inhibitors. There are subsets of patients who are outside of that subgroup who also derive some benefit, but patients with MSI-H tumors clearly have the most benefit.
There is an ongoing trial investigating chemotherapy versus a PD-1 inhibitor. It is accruing slowly, as it is only a small subset of patients, but there is already a lot of belief in the community that this group needs to receive a checkpoint inhibitor, explains McCollum.