MHC class I loss by tumor cells decreases tumor neoantigen presentation to the immune system and therefore represents a possible mechanism of immunotherapeutic resistance in cancers that otherwise could be good candidates for checkpoint inhibition (e.g. mismatch repair (MMR)-deficient and PD-L1-positive tumors). In this episode our guest, Dr. Anne Mills discusses her recent Modern Pathology publication on loss of MHC class 1 expression in some endometrial cancers. Study by Friedman et al, MHC class I loss in endometrial carcinoma: a potential resistance mechanism to immune checkpoint inhibition. Modern Pathology, 34, 627-636, 2021. https://www.nature.com/articles/s41379-020-00682-w