CD274 and neoplasm: FDA-approved PD-L1-depleting drugs such as cefepime72 and chlorambucil73 promote ubiquitination and proteasomal degradation of PD-L1 in ovarian cancer cell lines to regulate PD-L1 expression, and chlorambucil relatively selectively degrades PD-L1 from tumor cells rather than stromal or local immune PD-L1 degradation by ubiquitination in cells.73