Up to 12 Months of Efficacy and Safety of Elagolix Treatment in Women with Heavy Menstrual Bleeding Associated with Uterine Fibroids

Study Objective To evaluate the efficacy and safety of elagolix, an oral gonadotropin-releasing hormone antagonist, with hormonal add-back therapy in women with heavy menstrual bleeding (HMB) associated with uterine fibroids (UF) for up to 12-months. Design Elaris UF-EXTEND, a phase 3 extension study of two pivotal 6-month phase 3 studies, Elaris UF-1 and UF-2, evaluated the efficacy and safety of an additional 6-months of treatment (up to 12-months total) with elagolix 300mg twice daily (BID) with add-back therapy (1mg estradiol/0.5mg norethindrone acetate [E2/NETA] once daily) and elagolix 300mg BID alone as a reference arm. Setting Outpatient setting. Patients or Participants Participants were premenopausal women age 18-51 with HMB (>80mL/cycle menstrual blood loss [MBL]) associated with UF. A total of 433 women who completed the 6-month treatment period in the pivotal studies were enrolled in Elaris UF-EXTEND. Interventions Women who received elagolix+E2/NETA or elagolix alone in the pivotal studies continued to receive the same treatment while women who received placebo were randomized 1:1 to receive one of the two elagolix treatments. Here, we report data from women who received elagolix+E2/NETA or elagolix alone in both pivotal and extension studies. Measurements and Main Results MBL was assessed by the alkaline hematin method. Baseline was defined as the measure obtained before dosing in pivotal studies. 87.9% of women who received elagolix+E2/NETA and 89.4% who received elagolix alone had Conclusion Treatment with elagolix+E2/NETA for up to 12-months provided sustained MBL reduction comparable to elagolix alone with a safety profile consistent with preceding pivotal studies.