Antitumor activity of antiestrogenic phenylindoles on experimental prostate tumors.

Two antiestrogenic phenylindoles (D 16726 and D 15413) were tested for their prostatic tumor-inhibiting activity. Both compounds exerted a strong inhibitory effect on prostate and seminal vesicle weight of intact rats and mice comparable to that of diethylstilbestrol. Their estrogenic properties, however, are much lower than those of DES. Therefore, there is no direct correlation between estrogenic potency and inhibition of accessory sex organ weights. The tumor-inhibiting activity of D 16726 and D 15413 on the androgen-dependent R 3327 Dunning prostatic carcinoma and the human prostatic tumor PC 82 implanted in nude mice equals that of castration or of diethylstilbestrol. Both 2-phenylindoles had good affinities for estrogen receptors from calf uterine and R 3327 tumor cytosol, but no affinities for androgen and progesterone receptors. As these 2-phenylindoles have much lower estrogenic properties than diethylstilbestrol, they may also have low side-effects, and can therefore be of interest for the therapy of the prostatic carcinoma.