ObsEva reported positive Phase 3 trial results from the PRIMROSE 2 trial, which evaluated linzagolix alone and in combination with hormonal add-back therapy for the treatment of heavy menstrual bleeding (HMB) due to uterine fibroids. The trial met primary and secondary efficacy endpoints.

PRIMROSE 2 was a prospective, randomized, parallel group, double-blind, placebo-controlled trial and enrolled 535 women who received two dosing regimens of linzagolix, 100mg and 200mg once daily, alone and in combination with hormonal AB, for a treatment period of 12 months. Women participating in the trial did not receive Vitamin D or calcium supplementation. The trial was conducted in Europe and the US. The primary efficacy endpoint was the reduction in HMB. Responders were defined as patients with menstrual blood loss volume of ≤ 80 mL and ≥ 50% reduction from baseline in menstrual blood loss volume at 24 weeks, measured using the alkaline hematin method. 

The responder rate was 93.9% for women receiving 200 mg with ABT and 56.7% for women receiving 100 mg without ABT, compared to 29.4% in the placebo group. Both doses achieved significant rates of amenorrhea, reduction in pain and improvement in quality of life. Additionally, significant improvement in hemoglobin levels, a reduction in number of days of bleeding and reduction in uterine volume were observed. A significant reduction in fibroid volume was also observed for the 200 mg dose with ABT. Linzagolix was well-tolerated. The most frequently observed adverse events were headache, hot flushes, and anemia. 

Results from a second pivotal study, PRIMROSE 1, are expected in Q2 2020. Pending positive data, ObsEva anticipates submitting a Marketing Authorization Application with the European Medicines Agency by year-end 2020 and a New Drug Application with the U.S. Food and Drug Administration by Q1 2021.

About Linzagolix

Linzagolix (previously known as OBE2109) is a novel, oral, once daily, GnRH receptor antagonist with a potentially best-in-class profile. 

ObsEva licensed linzagolix from Kissei in late 2015 and retains worldwide commercial rights, excluding Asia, for the product.

About Uterine Fibroids

Uterine fibroids are common non-cancerous tumors that grow within the muscular wall of the uterus. They can vary in size and number and when symptomatic, are most often accompanied by heavy menstrual bleeding (HMB), anemia, abdominal pressure and pain, bloating, increased urinary frequency and reproductive dysfunction. Uterine fibroids are associated with an increased risk of pregnancy complications such as infertility, miscarriage, placental abruption, and early onset of labor. According to a study published in the American Journal of Obstetrics & Gynecology in 2003, uterine fibroids affect an estimated 20 to 40 percent of women over the age of 30 in the United States based on clinical cases and women who undergo treatment.

While medical, surgical and minimally invasive treatments are available, the standard of care for symptomatic uterine fibroids is a hysterectomy or, in women who wish to preserve their fertility, surgical removal of the fibroid(s).

Source: ObsEva

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