1-[4-(N,N-bis-beta-chloroethylcarbamoyloxy)-phenyl]-1,2-bis- (hydroxyphenyl)-but-1-enes: drugs specifically targeted against estrogen receptor positive mammary tumors.

1-[4-N,N-bis-2-chloroethylcarbamoyloxy)-phenyl]-1-(4-hydroxyphenyl )-2- phenylbut-1-ene (1) is a cytotoxic estrogen with a selective antitumor effect only on estrogen receptor (ER) containing tumors. In order to improve the ER affinity and thereby the antitumor activity of 1 a second OH-group in position 3 or 4 was introduced into the phenyl ring at C-atom 2 (8 and 9) and the respective acetates 10 and 11 were prepared. These modifications caused an enhanced ER affinity of 8-11 as compared to 1. The estrogenic properties were only slightly increased. In vitro, an enhanced antitumor effect on the ER positive MCF-7 mammary tumor cell line was determined for 8-11 as compared to 1 leading to inhibitions up to 90%. In vivo, 8-11 caused a pronounced growth inhibition of the hormone-dependent MXT M3.2 mammary tumor of the mouse though these effects were not better than those caused by 1 except the acetate 10, which inhibited tumor growth by 88%. These data show that the introduction of a second OH-group into 1 not only increased ER affinity, but also the antitumor activity in vitro and to a lesser extent in vivo in ER positive tumors. As none of these compounds had any significant effect on ER negative tumor models, 8-11 can be regarded as cytotoxic estrogens with a specific ER-mediated effect selectively on ER positive tumors.