Forendo Pharma Oy is developing inhibitors of hydroxysteroid 17-beta dehydrogenase 1 to treat endometriosis without depleting circulating estrogen, thus avoiding side effects of available therapies.

In endometriosis, tissue similar to endometrium in the uterus grows in the peritoneal cavity, causing pelvic pain and often leading to infertility. The causes are unknown, and drugs for the indication mainly aim at reducing pain.