Lifeboat Foundation

High Microsatellite Instability is an emerging biomarker for immune-oncology that can be predictive of positive response to immunotherapy.

Tumors with defects in the expression of functional MMR (dMMR) proteins often have somatic mutations that produce novel or “foreign” proteins. These proteins can be immunogenic. As a result, these tumors are effective at priming an immune response and subsequently susceptible to immunotherapies. Because MSI can be the first evidence of an MMR deficiency, MSI-H status is predicative of a positive response to immunotherapies such as immune checkpoint blockade inhibitors.