Reduction of Heavy Menstrual Bleeding in Women Not Designated as Responders to Elagolix Plus Add Back Therapy for Uterine Fibroids

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