Immunotherapy Sensitivity of Mismatch Repair-Deficient Cancer: Mutation Load Is Not Enough.

Abundant neoantigens are considered responsible for the immunotherapy sensitivity of mismatch repair-deficient (MMRd) cancers. In this issue of Cancer Cell, two papers show that MLH1 mismatch repair gene loss promotes cGAS-STING activation, interferon secretion, and T cell priming. This may be essential for the high immunotherapy sensitivity in MMRd cancer.