CD274 and endometrial carcinoma: Studies have shown that PD-1 and PD-L1 are expressed in 80% of primary endometrial carcinoma patients and almost 100% of metastatic tumors (Mo et al., 2016), The inhibitor pembrolizumab was FDA-approved for use in microsatellite instability-high (MSI-H) or mismatch repair (MMR)-deficient endometrial carcinoma patients (Le et al., 2017).