An anti-PD-L1/TGF-βRII bifunctional antibody (M7824) is currently undergoing clinical evaluation either as a single agent in stage II–III HER2+ BC (NCT03620201) or in combination with radiation (NCT03524170), with eribulin (NCT03579472) or with a brachyury-targeting virus-based vaccine plus trastuzumab emtansine or the class I HDAC inhibitor entinostat in TNBC patients (NCT04296942). This evidence concerns the gene HDAC9 and breast cancer.