Dr. Powell on MSI and dMMR as Potential Biomarkers in Endometrial Cancer

Matthew Powell, MD, associate professor, Obstetrics and Gynecology, Division of Gynecologic Oncology, Washington University School of Medicine, discusses microsatellite instability (MSI) and mismatch repair deficiency (dMMR) as potential biomarkers in endometrial cancer.

About one-third of patients with newly diagnosed endometrial cancer will express MSI or dMMR, says Powell. Recent data suggests these factors could be predictive of immunotherapy response. Clinicians can find these molecular markers by using immunohistochemistry and testing the 4 major genes expressed in patients with dMMR. Next-generation sequencing is now used to test for MSI. Powell says that recent data show a 40% to 60% response rate in these patient populations when treated with immunotherapy. The best part about the responses, he adds, is that they seem to be durable.

These data suggest that every newly diagnosed patient with endometrial cancer should be tested for MSI and dMMR. These attributes are also seen in ovarian cancer, but very rarely, Powell says.