Effect of Elagolix on Menstrual Blood Loss in Women With Uterine Fibroids and Adenomyosis [15B]

INTRODUCTION: Evaluate the efficacy of elagolix with add-back therapy on menstrual blood loss (MBL) and safety in women with uterine fibroids (UF), heavy menstrual bleeding (HMB) and adenomyosis. METHODS: Pooled data from two investigational, IRB approved, 6-month, randomized, double-blind, placebo-controlled phase 3 studies, Elaris UF-1 and UF-2, was used to conduct a subset analysis in premenopausal women (18–51 years) with HMB (>80mL MBL/cycle) associated with UF and baseline adenomyosis diagnosed by ultrasound and/or MRI. Primary endpoint was the proportion of women with <80mL MBL during the final month and ≥50% reduction in MBL from baseline to final month. Secondary and other efficacy endpoints included proportion of women who achieved amenorrhea or suppression of bleeding during the final month. MBL was assessed with alkaline hematin method. Adverse events (AEs) and bone mineral density (BMD) were monitored. RESULTS: Of 790 women treated, 126 (16%) had adenomyosis at baseline. Proportion of responders for the primary endpoint was significantly greater ( P <.001) for elagolix+E2/NETA [76.8% (95% CI 65.84, 87.82)] compared to placebo [12.1% (95% CI 0.97, 23.15)]. Responder rate was significantly greater ( P <.001) for elagolix+E2/NETA versus placebo for amenorrhea and suppression of bleeding. These results, along with AEs and mean change in lumbar BMD from baseline to month 6, were consistent with the all-subject group. CONCLUSION: In women with HMB associated with UF and co-existing adenomyosis at baseline, elagolix +E2/NETA significantly reduced MBL versus placebo similar to the all-subject group suggesting that elagolix is effective in reducing HMB in women with UF despite the presence of adenomyosis.