Dr. Kasi on Role of Immunotherapy in mCRC

Pashtoon M. Kasi, MD, MBBS, MS, assistant professor of oncology and senior associate consultant in the Division of Hematology/Oncology at Mayo Clinic, discusses the role of immunotherapy in the treatment of patients with metastatic colorectal cancer (mCRC).

The vast majority of patients with mCRC are left with traditional cytotoxic chemotherapy, but there is a small subset of patients who benefit from checkpoint inhibitors. These patients have tumors that are characterized by mismatch repair deficiency (dMMR) or have microsatellite instability-high (MSI-H) tumors. Patients with Lynch syndrome have also been found to derive benefit from immunotherapy, Kasi notes.

Immunotherapy is not only FDA-approved in this setting as a single agent, but the combination of nivolumab (Opdivo) and ipilimumab (Yervoy) is also an option for these patients. By default, Kasi says, researchers should now check every patient with stage IV CRC for dMMR or MSI-H. While these patients only account for about 5% of the overall population of those with mCRC, these therapies are highly likely to have significant benefit. Notably, Kasi adds, that the trait of dMMR is known to cause a high number of mutations in the tumor, which increases the likelihood of response to immunotherapy.