Molecular pathology selected abstracts
December 2023—Immune checkpoint blockade therapy has dramatically altered treatment options for a variety of cancers. A high tumor mutation burden (TMB) is considered one of the strongest predictors of immune checkpoint blockade response. DNA mismatch repair deficiency (MMRd) is associated with a high TMB, and many tumors associated with MMRd have shown excellent response to immunotherapy. However, most MMRd tumors do not show durable response to treatment with immune checkpoint blockade (ICB). Intratumor heterogeneity may further mediate response to ICB therapy.