Effect of Fluorination on the Pharmacological Profile of 11 beta Isomers of Fulvestrant in Breast Carcinoma Cells

摘要

We describe the synthesis of an 11 beta isomer 3 of the steroidal antiestrogen fulvestrant 2. Partial fluorination of the 11 beta side chain in 3 leads to 4, which still shows strong antiproliferative activity on MCF-7 cells. However, unlike 2 and 3, compound 4 fails to down-regulate estrogen receptor alpha (ER alpha). This result suggests that ER alpha down-regulation is not a sine qua non condition for the antitumor activity of steroidal antiestrogens.