Treatment of Endometriosis-Associated Pain with Elagolix, an Oral GnRH Antagonist.

BACKGROUND: Endometriosis is a chronic, estrogen-dependent condition that causes dysmenorrhea and pelvic pain. Elagolix, an oral, nonpeptide, gonadotropin-releasing hormone (GnRH) antagonist, produced partial to nearly full estrogen suppression in previous studies. METHODS: We performed two similar, double-blind, randomized, 6-month phase 3 trials (Elaris Endometriosis I and II [EM-I and EM-II]) to evaluate the effects of two doses of elagolix - 150 mg once daily (lower-dose group) and 200 mg twice daily (higher-dose group) - as compared with placebo in women with surgically diagnosed endometriosis and moderate or severe endometriosis-associated pain. The two primary efficacy end points were the proportion of women who had a clinical response with respect to dysmenorrhea and the proportion who had a clinical response with respect to nonmenstrual pelvic pain at 3 months. Each of these end points was measured as a clinically meaningful reduction in the pain score and a decreased or stable use of rescue analgesic agents, as recorded in a daily electronic diary. RESULTS: A total of 872 women underwent randomization in Elaris EM-I and 817 in Elaris EM-II; of these women, 653 (74.9%) and 632 (77.4%), respectively, completed the intervention. At 3 months, a significantly greater proportion of women who received each elagolix dose met the clinical response criteria for the two primary end points than did those who received placebo. In Elaris EM-I, the percentage of women who had a clinical response with respect to dysmenorrhea was 46.4% in the lower-dose elagolix group and 75.8% in the higher-dose elagolix group, as compared with 19.6% in the placebo group; in Elaris EM-II, the corresponding percentages were 43.4% and 72.4%, as compared with 22.7% (P<0.001 for all comparisons). In Elaris EM-I, the percentage of women who had a clinical response with respect to nonmenstrual pelvic pain was 50.4% in the lower-dose elagolix group and 54.5% in the higher-dose elagolix group, as compared with 36.5% in the placebo group (P<0.001 for all comparisons); in Elaris EM-II, the corresponding percentages were 49.8% and 57.8%, as compared with 36.5% (P=0.003 and P<0.001, respectively). The responses with respect to dysmenorrhea and nonmenstrual pelvic pain were sustained at 6 months. Women who received elagolix had higher rates of hot flushes (mostly mild or moderate), higher levels of serum lipids, and greater decreases from baseline in bone mineral density than did those who received placebo; there were no adverse endometrial findings. CONCLUSIONS: Both higher and lower doses of elagolix were effective in improving dysmenorrhea and nonmenstrual pelvic pain during a 6-month period in women with endometriosis-associated pain. The two doses of elagolix were associated with hypoestrogenic adverse effects. (Funded by AbbVie; Elaris EM-I and EM-II ClinicalTrials.gov numbers, NCT01620528 and NCT01931670 .).

Elagolix for the management of heavy menstrual bleeding associated with uterine fibroids: results from a phase 2a proof-of-concept study.

OBJECTIVE: To evaluate the safety and efficacy of elagolix vs. placebo and elagolix with low-dose E2/progestogen add-back therapy. DESIGN: Proof-of-concept, dose-ranging, multiple-cohort study. SETTING: Clinics. PATIENT(S): Premenopausal women with fibroids and heavy menstrual bleeding (menstrual blood loss [MBL] >80 mL per cycle). INTERVENTION(S): Three months' treatment with elagolix alone: 100 mg twice daily (BID), 200 mg BID, 300 mg BID, 400 mg once daily (QD), or 600 mg QD (all but the 600 mg QD arm were placebo controlled); or elagolix plus add-back therapy: 200 mg BID plus continuous low-dose E2 0.5 mg/norethindrone acetate 0.1 mg or elagolix 300 mg BID plus E2 1 mg continuously and cyclical P 200 mg. MAIN OUTCOME MEASURE(S): Least-squares mean percentage change in MBL; adverse events (AEs). RESULT(S): Mean age was 41.8 years; 73.8% were black; mean baseline MBL was 267 mL. Of randomized women (elagolix alone, n = 160; placebo, n = 50; elagolix with add-back therapy, n = 61), 228 of 271 completed the 3-month treatment period. The MBL percentage change from baseline to last 28 days was significantly greater with elagolix alone (range, -72% to -98%; dose-dependent reduction was highest with 300 mg BID) vs. placebo (range, -8% to -41%); mean percentage changes with add-back regimens were -80% to -85%. Overall AEs were dose independent (elagolix alone, 70.0%-81.3%) but lower with placebo (56.0%) and add-back regimens (55.6%-70.6%). Hot flush was the most common AE (elagolix alone, 45.5%-62.5%; placebo, 12.0%; add-back regimens, 18.5%-26.5%). CONCLUSION(S): Elagolix significantly reduced heavy menstrual bleeding in women with fibroids. Low-dose add-back regimens substantially reduced flushing. CLINICAL TRIAL REGISTRATION NUMBER: NCT01441635.