TACSTD2 and breast cancer: As mentioned previously, sacituzumab govitecan is composed of an antibody coupled to topoisomerase I inhibitor (SN-38) through a proprietary hydrolysable linker, targeting human trophoblast cell-surface antigen 2 (Trop-2) which is expressed in the majority of breast cancers including TNBC [123,124,125,126,127,128].