Myriam Chalabi, MD, a medical oncologist at the Netherlands Cancer Institute, discusses the utility of microsatellite instability (MSI) testing in colorectal cancer (CRC).

MSI testing is widely utilized for patients with CRC, says Chalabi. It’s critical to understand MSI test results because they can help guide treatment selection, especially amid the rise of several effective immunotherapy options. Notably, MSI testing results can be particularly beneficial for patients with metastatic CRC, larger tumors, or those who need induction therapy prior to undergoing surgery. Patients at the Netherlands Cancer Institute are typically recommended for clinical trials that are evaluating the role of neoadjuvant immunotherapy, such as the NICHE trial (NCT03026140), Chalabi says. 

The NICHE trial is currently recruiting and is the first neoadjuvant trial to evaluate the role of ipilimumab (Yervoy) in combination with nivolumab (Opdivo) in patients with early-stage CRC. Patients globally are recommended for this study, says Chalabi. Moreover, based on initial findings from the NICHE trial, ipilimumab/nivolumab may be preferrable to chemotherapy, which is the standard of care in this setting in several parts of the world, Chalabi explains. In the United States, immunotherapy is the standard for patients with MSI tumors and metastatic disease; however, in the Netherlands, patients must be enrolled in a clinical trial, Chalabi concludes.

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Myriam Chalabi, MD, discusses the utility of microsatellite instability (MSI) testing in colorectal cancer, 

Dr. Chalabi on the Role of MSI Testing 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.

Myriam Chalabi, MD, highlights the importance of testing for microsatellite instability and mismatch repair deficiency in colorectal cancer. 

Myriam Chalabi, MD

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Dr. Chalabi on the Role of MSI Testing in CRC

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