September 15, 2021

New Drug Application submitted to U.S. FDA for Linzagolix for the treatment of uterine fibroids

Kissei Pharmaceutical Co., Ltd (Head office: Matsumoto, Nagano; Chairman and CEO: Mutsuo Kanzawa; "Kissei") is pleased to announce that a New Drug Application for our original compound, the GnRH antagonist "Linzagolix (KLH-2109/OBE2109)" that was licensed out to ObsEva (ObsEva SA, Main Office: Geneva, Switzerland, CEO: Brian O'Callaghan) for global territory except for Asia including Japan, has been submitted to the U.S. FDA for the treatment of uterine fibroids.

The phase 3 clinical program in uterine fibroids consisted of 2 studies: PRIMROSE 1 and PRIMROSE 2. In both studies, 100mg and 200mg with and without add-back therapy (ABT) were administered for 52 weeks, with post-treatment follow-up for 24 weeks. The primary endpoint of reduction in heavy menstrual bleeding was met and good safety tolerance was confirmed. From the results obtained, linzagolix is expected to provide flexible dosing options depending on individual patient requirements for the treatment of uterine fibroids.

For more details on ObsEva's release, please refer to their web page.


This matter has negligible effects on Kissei's consolidated business forecasts for the fiscal year ending in March 2022.


About Linzagolix (KLH-2109):

Linzagolix is a novel, orally administered GnRH receptor antagonist. Linzagolix acts by antagonizing the GnRH receptor in the pituitary gland, ultimately reducing estrogen production by the ovaries. In November 2015, Kissei licensed out exclusive rights to develop and market in countries excluding part of Asia such as Japan to ObsEva. The uterine fibroids Phase 3 program comprised two double-blind, placebo-controlled studies (PRIMROSE 1 and 2) to support the approval of Linzagolix for the treatment of heavy menstrual bleeding associated with uterine fibroids. ObsEva is also conducting a phase 3 clinical trial for the endometriosis indication.

About Phase 3 clinical trials for uterine fibroid (PRIMROSE studies):
PRIMROSE 1 and PRIMROSE 2 are randomized double-blinded placebo-controlled Phase 3 trials which assessed the efficacy and safety of Linzagolix 100mg and 200mg with and without ABT in patients with heavy menstrual bleeding associated with uterine fibroids. PRIMROSE 1 was conducted in the U.S. with 574 women, whilst PRIMROSE 2 was conducted in Europe and in the United States with 535 women registered. Both studies had a treatment period of 52 weeks and a post-treatment follow-up period of 24 weeks. Since December 2019, ObsEva has released the 24-week primary analyses of the PRIMROSE 2 and PRIMROSE 1 trials, the results following 52-weeks of treatment, and the post-treatment follow-up results at 76 weeks.

About Hormonal Add-back Therapy:

Hormonal Add-back therapy (ABT), estradiol 1mg/ Norethisterone 0.5mg, is exogenous hormone replacement to prevent bone mineral density loss in patients treated with Linzagolix.

About ObsEva:

ObsEva is a biopharmaceutical company developing and commercializing novel therapies to improve women's reproductive health and pregnancy. Through strategic in-licensing and disciplined drug development, ObsEva has established a late-stage clinical pipeline with development programs focused on new therapies for the treatment of uterine fibroids, endometriosis, and preterm labor. ObsEva is listed on the Nasdaq Global Select Market and is traded under the ticker symbol "OBSV" and on the SIX Swiss Exchange where it is traded under the ticker symbol "OBSN". For more information, please visit