Compound 56, with a cinnamic acid linked to an ether function to the position 4, and a trifluormethyl group at position 4′ and powerful ER down-regulation (IC50 = 3 nM), is the result of the pharmacomodulation of other 7-hydroxycoumarin precursors with previously reported antitumor effects against chemically induced mammary tumors such as selective estrogenic receptor down-regulators [26]. This evidence concerns the gene ESR1 and breast cancer.