ObsEva's Menstrual Bleeding Drug Produces 'Best-In-Class' Response In Late-Stage Study

Swiss biopharma Obseva SA OBSV, which is developing orally administered, clinical-stage compounds to treat women's reproductive health conditions, announced a positive late-stage clinical readout Monday for its investigational compound to treat heavy menstrual bleeding due to uterine fibroids.

ObsEva saw its shares a decline steeply in early November due to a failed trial of nolasiban, another pipeline asset. 

ObsEva's Study Results 

The Phase 3 study dubbed PRIMROSE 2 met the primary and secondary efficacy endpoints, ObsEva said.

The study evaluated once-daily oral linzagolix in 100mg and 200mg doses, with and without hormonal add-back therapy, or ABT,

The primary efficacy endpoint was the reduction in heavy menstrual bleeding. 

The responder rate was 93.9% for women receiving 200mg linzagolix with ABT and 56.7% for women receiving 100mg without ABT versus 29.4% for the placebo group. The company termed the response for the 200mg dose as "best-in-class." 

Both doses achieved significant rates of amenorrhea, reduction in pain and improvement in quality of life, according to ObsEva. 

Linzagolix also led to significant improvement in hemoglobin levels, a reduction in the number of days of bleeding and a reduction in uterine volume, the company said. 

ObsEva noted a significant reduction in fibroid volume for the 200mg dose with ABT.

The safety profile was in-line with expectations, confirming that linzagolix was well-tolerated.

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Why Linzagolix Data Is Important 

Linzagolix is a GnRH antagonist that is being developed in late-stage studies for endometriosis and uterine fibroids. 

ObsEva licensed the compound from the Japanese biotech Kissei in late 2015.

A dire need exists for non-surgical alternatives for uterine fibroids to reduce the effects of heavy menstrual bleeding.

"The prospects for a medical treatment with multiple dosing options would address a need for this diverse population of women. I am particularly impressed with the 94% responder rate and 80% amenorrhea rate that linzagolix has shown," Dr. Hugh Taylor, chair of obstetrics and gynecology at the Yale University, said in a statement. 

The 50% response shown by patients taking the 100mg dose without ABT provides a meaningful option for women who cannot or do not want to take exogenous hormones.

ObsEva said it expects results form the Phase 3 PRIMROZSE 1 study conducted in the U.S. in the second quarter of 2020.

Provided the study also ends with positive results, the company plans to submit a Marketing Authorization Application in Europe by the end of 2020 and a New Drug Application in the U.S. by the first quarter of 2021.

ObsEva shares were down 13.79% at $3.94 at the time of publication Monday.