Faculty Perspectives: Clinical Relevance and Rationale of Using MSI-H/dMMR Biomarkers in Immunotherapy of Colorectal Cancer and Other Solid Tumors | Part 3 of a 4-Part Series

There is renewed interest in MSI analysis because the MSI-H/dMMR phenotype has emerged as an actionable predictive biomarker for immune checkpoint blockade therapy in different cancer types.

Genotyping tumors for microsatellite instability (MSI) has taken on new importance in the world of oncology. MSI screening has long been recognized as important in the care of patients with colorectal cancer (CRC) or endometrial cancer, and high-level MSI (MSI-H) is now being recognized as a potential marker for germline mutations in certain DNA mismatch-repair (MMR) genes that lead to the development of Lynch syndrome.

Previously, testing for microsatellite instability (MSI) or mismatch repair deficiency (dMMR) has been performed as a screening test to identify patients with Lynch syndrome in colorectal and endometrial cancer, in addition to providing prognostic and predictive data in colorectal cancer (CRC).