Dual targeting BC agents include ER/tubulin [50], tubulin/HSP90 [51], and ER/AI, e.g., norendoxifen and endoxifen [52,53,54] and related compounds [55,56], sulfatase/AI [57], tubulin/sulfatase [58], ER/histone deacetylase [59], and ERα/aromatase PROTAC degraders [60]. The gene discussed is ESR1; the disease is breast cancer.