Dr. Chalabi on the Importance of Testing for MSI and dMMR in CRC

Myriam Chalabi, MD, a medical oncologist at the Netherlands Cancer Institute, highlights the importance of testing for microsatellite instability (MSI) and mismatch repair deficiency (dMMR) in colorectal cancer (CRC).

Approximately 10 years ago, patients with CRC were tested for MSI and dMMR to determine whether a patient or their family members were at risk for Lynch syndrome. However, with the rise immunotherapy in CRC, MSI and dMMR have gained significant relevance in the field because they can guide treatment selection, Chalabi says.

For example, on June 29, 2020, the FDA approved pembrolizumab (Keytruda) monotherapy for the frontline treatment of patients with unresectable or metastatic MSI-high or dMMR CRC. As such, ​patients with MSI-high status may benefit from pembrolizumab, Chalabi concludes.