Therapeutically active estratrienthiazole derivatives as inhibitors of 17 B-hydroxysteroid dehydrogenase, type 1

The invention relates to compounds of formula (I) and pharmaceutically acceptable salts thereof wherein R1 to R6 are as defined in the claims. The invention further relates to their use as inhibitors of 17 -HSD and in treatment or prevention of steroid hormone de- pendent diseases or disorders, such as steroid hormone dependent diseases or disorders requiring the inhibition of the 17 -HSD1 enzyme and/or requiring the lowering of the endogenous estradiol concentration. The present invention also relates to the preparation of the aforementioned compounds and to pharmaceutical compositions comprising as an active ingredient(s) one or more of the aforementioned compounds or pharmaceutically acceptable salts thereof.