Owens, Charlotte D.

Objective: To assess outcomes of women with uterine fibroids (UFs) and heavy menstrual bleeding (HMB) treated with 300 mg elagolix twice daily plus add-back therapy (E2 1 mg/NETA 0.5 mg once daily) or placebo who were not considered responders in pooled analysis of two phase 3, 6-month randomized clinical trials (Elaris UF-1 and UF-2). Methods: Responders were defined as women who met both primary end point bleeding criteria (<80 mL menstrual blood loss [MBL] during the final month and ≥50% reduction in MBL from baseline to the final month) and either completed the study or discontinued due to predefined reasons. Thus, women termed nonresponders who were analyzed in this study who met neither or one bleeding end point or met both criteria but prematurely discontinued treatment because of adverse events, perceived lack of efficacy, or required surgical or interventional treatment for UFs were analyzed in this study. This post hoc analysis assessed mean changes from baseline in MBL, as well as adverse events. Results: Among 367 women receiving elagolix with add-back with observed data, 89 (24%) were not considered responders. Within this subset, 17 (19%) women met both bleeding criteria but prematurely discontinued treatment for the reasons mentioned above, while 23 (26%) met one bleeding criterion and 49 (55%) met neither bleeding criteria, regardless of discontinuation status. Among all nonresponders, a numerical trend toward greater mean reductions in MBL was observed in those receiving elagolix with add-back, compared with placebo group nonresponders. No differences in adverse events were observed between responders and nonresponders. Conclusion: Forty of 89 (45%) women with HMB and UFs who were classified as nonresponders in the UF-1 or UF-2 trials may have had a clinically meaningful response to elagolix with add-back therapy because they met at least one of the objective bleeding criteria. Clinical Trial Registration: Clinicaltrials.gov, NCT02654054 and NCT02691494. (NEJM 2020; 382:328–340) DOI: 10.1056/NEJMoa1904351

INTRODUCTION: Elagolix, an oral gonadotropin-releasing hormone antagonist, with and without add-back therapy, was evaluated in premenopausal women with heavy menstrual bleeding (HMB; greater than 80 mL/month menstrual blood loss [MBL]) associated with uterine fibroids (UF). METHODS: This double-blind, randomized, placebo-controlled, parallel group study evaluated the efficacy and safety of 6 months of treatment in 2 cohorts, with four arms/cohort: elagolix alone as 300 mg twice daily in cohort 1 (C1) and 600 mg once daily in cohort 2, and in both cohorts, placebo, elagolix with add-back therapy of estradiol (E2)/norethindrone acetate (NETA), low dose 0.5 mg E2/0.1 mg NETA (LDA), or standard dose 1.0 mg E2/0.5 mg NETA (SDA). The primary endpoint was the percentage of women with less than 80 mL MBL assessed by the alkaline-hematin-method and at least 50% reduction in MBL from baseline to the last 28 days of treatment. Adverse events (AE), changes in bone mineral density (BMD) and quality of life (QoL) were assessed. RESULTS: In C1, 259 women were randomized and treated; 80% completed treatment. C1 responses for the primary endpoint were 92% in elagolix alone, 85% elagolix+LDA, 79% elagolix+SDA, and 27% placebo (all p < .001 vs. placebo). Add-back therapy attenuated hot flushes and lumbar spine BMD decreases in a dose-dependent manner; there were no statistically significant differences in BMD between elagolix+SDA and placebo at month 6. All elagolix treatments were associated with improved QoL. Results were similar in C2. CONCLUSION: Elagolix with or without add-back significantly reduced MBL in UF-associated HMB. Hot flushes and BMD decreases were reduced by add-back in a dose-dependent manner.