Antitumour activity of folligen, a novel gonadotropin-releasing hormone analogue against DMBA-induced tumours in the rat.

A novel chicken gonadotropin-releasing hormone (GnRH) analogue (Folligen), which has a different mechanism of action than superactive mammalian GnRH analogues, has been developed. In this study we report that in 9,10-dimetyl-1,2-bezanthracene- induced mammary carcinomas in rats, Folligen caused an almost 100% tumour remission during a 3-week daily treatment, without blocking ovarian functions. It decreased oestradiol but not to castration levels, while progesterone was not decreased at all; instead, it was slightly stimulated. The histological picture of the ovaries showed no signs of the inhibition of ovarian functions, but the presence of developing follicles and corpora lutea. In comparison, superactive mammalian GnRH analogues caused similar tumour remission but with hormonal castration and a complete block of ovarian functions.