Additionally, the fact that the engage of PD-L1 with PD-1 inhibits the proliferation and cytokine production by T cells lymphocytes [104, 105] and that the PD-L1 also expresses on a number of human cancers like urothelial, gastrointestinal, lung, breast, melanoma and ovarian cancer [102, 106–114] prompted to the development of different mAbs to target either the receptor or the ligand. Here, CD274 is linked to ovarian carcinoma.