RPL22 Expression Identifies a Transcriptional Subset of MLH1 Deficient Endometrial Cancers that Impacts Tumor Infiltrating Lymphocytes [transcript]

RPL22 expression is lost is ~30% of MSI-high endometrial cancers, and the consequences of RPL22 loss are still unknown. The purpose of this study was to determine the consequences of RPL22 loss in both the tumor and immune microenvironment of MSI-high endometrial cancers. We determined that the number of CD8+ T cells in RPL22 negative tumors is significantly lower than in RPL22 positive tumors and thatRPL22 positive tumors have distinct transcriptional profiles characterized by upregulation of immune pathways. Overall design: Sixteen formalin-fixed, paraffin embedded MLH1 deficient endometrial tumors were analyzed using whole transcriptome digital spatial analysis. Eleven tumors were RPL22 positive. Of these, 5 were immune high (as determined by quanitifying CD8+ T cells in the whole tumor) and 6 were immune low. Five tumors were RPL22 negative and immune low. Six regions of interest (ROIs) were chosen for each tumor. Three ROIs were of tumor cells, and 3 ROIs were of immune cells in the periphery of the tumor.