A number of approaches to the design of dual targeting breast cancer agents have been reported e.g., ER/tubulin [78], tubulin/HSP90 [79], tubulin/HSP27 [80], ER/AI e.g., norendoxifen [81,82], and endoxifen [83], sulfatase/AI [84], tubulin/sulfatase [85,86] and tubulin/angiogenesis (vascular endothelial growth factor receptor-2 (VEGFR2) [87]. Here, ESR1 is linked to breast cancer.