Swiss-based biopharmaceutical firm ObsEva has commenced its Phase III clinical trial programme of OBE2109 to treat uterine fibroids (UF).
OBE2109 is an oral gonadotropin-releasing hormone (GnRH) receptor antagonist that decreases estrogen production by the ovaries in pre-menopausal women.
The clinical programme includes two international, double-blind, placebo-controlled, Phase III trials known as PRIMROSE 1 and PRIMROSE 2 that will evaluate 100mg or 200mg of OBE2109.
To be conducted at approximately 200 sites in the US and Europe, the trials have begun enrolment and are designed to recruit a total of up to 1,000 women with UF-associated heavy menstrual bleeding (HMB).
ObsEva co-founder and CEO Ernest Loumaye said: "We are evaluating long-term administration of OBE2109 in two dosing regimens, as a stand-alone therapy or in association with add-back therapy, designed to offer the broad patient population the personalised options needed for symptom relief with fewer side effects and complications.
"Owing to its consistent PK / PD profile, the lower dose of OBE2109 is designed to allow for the maintenance of estradiol levels within an acceptable range that reduces HMB while mitigating bone mineral density loss and other adverse effects, eliminating the need for systematic add-back therapy."
The trials will assess the safety of long-term treatment of OBE2109 over a period of about 52 weeks, with or without low doses of hormonal add-back therapy.
The trials' primary outcome is a clinically meaningful and statistically significant decrease in menstrual bleeding as measured by the alkaline hematin method.
The PRIMROSE trials will also include safety assessments such as a centralised examination of bone mineral density changes measured by dual-energy X-ray absorptiometry (DXA).
In 2015, ObsEva licenced OBE2109 from Japanese pharmaceutical firm Kissei and holds its worldwide commercial rights aside from in the Asian market.