Defective mismatch repair associated mutational signatures, a prognostic and predictive biomarker in endometrial cancer.

5528 Background: Mismatch repair (MMR) deficiency is the distinguishing molecular feature of a significant portion of endometrial cancers (UCEC), and tumors with MMR deficiency have been identified as candidates for immune checkpoint blockade therapy. We studied MMR deficiency in UCEC using defective mismatch repair associated mutational signatures (MMRd-ams). Methods: WES-derived somatic mutation data of 531 UCEC samples from TCGA Pan-Cancer...