December 9, 2019

Positive results from uterine fibroids phase-III PRIMROSE 2 trial of Linzagolix

Kissei Pharmaceutical Co., Ltd. (Chairman and CEO: Mutsuo Kanzawa; "Kissei") announced today (December 9, CET) that ObsEva SA (head office: Geneva, Switzerland; Co-Founder and CEO: Ernest Loumaye), reported positive 24-week results from the PRIMROSE 2 phase-III clinical trial of linzagolix (generic name, Code name in Japan:KLH-2109, International code name:OBE2109) for the treatment of uterine fibroids.

Kissei granted ObsEva exclusive worldwide rights on linzagolix, excluding Asia in November 2015. Linzagolix is a novel, orally administered GnRH receptor antagonist discovered by Kissei. Currently, ObsEva is conducting pivotal phase-III trials for both treatments of uterine fibroids and endometriosis. PRIMROSE 1 and 2 are two of these clinical trials that evaluates patients with heavy menstrual bleeding (HMB) associated with uterine fibroids.

The PRIMROSE 2 trial enrolled 535 women with uterine fibroids. The trial was conducted in Europe and the US, and evaluated the efficacy and safety of once daily oral linzagolix, including 100 mg and 200 mg doses, both with and without hormonal add-back therapy (ABT). The primary efficacy endpoint was the reduction in HMB; responders were defined as patients with menstrual blood loss volume of ≤ 80 mL and a 50 percent or greater reduction from baseline in menstrual blood loss volume at 24 weeks.The patients are treated for up to 52 weeks to evaluate the safety of long-term treatment. The responder rate for 200 mg with ABT group and 100 mg without ABT group were significantly higher compared to placebo. Both doses achieved significant improvement on secondary efficacy endpoints such as amenorrhea, reduction in pain, and improvement in quality of life. The overall safety profile was in line with expectations and confirmed that linzagolix was well-tolerated. Mean percentage change from baseline in BMD was consistent with the previous trial.

ObsEva plans to file an MAA submission by year-end 2020 and NDA submission by Q1 2021 for the indication of uterine fibroids through steadily conducting the PRIMROSE 1 and 2 trials to verify the efficacy and safety of linzagorix.

For details on the announcements of ObsEva, please refer to the press release on the website of the company.

These clinical results have negligible effects on Kissei's consolidated business forecasts for the fiscal year ending in March 2020.


About Linzagolix:

Linzagolix is a novel, orally administered GnRH (gonadotropin releasing hormone) receptor antagonist. Linzagolix acts by binding to and blocking the GnRH receptor in the pituitary gland, ultimately reducing estrogen production by the ovaries.

About Hormonal Add-back Therapy:

Hormonal Add-back therapy (ABT) is treatment of exogenous estrogen replacement to prevent excessive estrogen reduction with the drugs. It reduces the side effects such as bone mineral density loss while maintaining the therapeutic effects.

About ObsEva:

ObsEva SA is a Swiss clinical-stage biopharmaceutical company focused on the development and commercialization of novel therapeutics for serious conditions that compromise a woman's reproductive health and pregnancy. ObsEva is listed on the Nasdaq Global Select Market and is trading under the ticker symbol "OBSV" and on the SIX Swiss Exchange where it is trading under the ticker symbol "OBSN". For more information about ObsEva SA, please visit