In the pivotal LIBERTY 1 and 2 trials and long-term extension study, once-daily relugolix combination therapy (40 mg relugolix, 1 mg estradiol, 0.5 mg norethindrone acetate) reduced menstrual blood loss volume and pain among women with uterine fibroids. Relugolix combination therapy was well tolerated with preservation of bone mineral density through 52 weeks.

This study aimed to report the 2-year relugolix combination therapy efficacy and safety results of the phase 3 LIBERTY randomized withdrawal study.

Women with uterine fibroid-associated heavy menstrual bleeding who completed the 24-week LIBERTY 1 or 2 trials, followed by the 28-week long-term extension study (up to 52 weeks total treatment), and who met the responder criteria (menstrual blood loss volume <80 mL and ≥50% reduction from pivotal study baseline at week 48 [week 24 of long-term extension]) were randomized in a 1:1 ratio to either blinded treatment with relugolix combination therapy or placebo for 52 weeks (total treatment period, 104 weeks). For women who had a relapse of heavy menstrual bleeding during the study (menstrual blood loss volume ≥80 mL), open-label relugolix combination therapy was offered. The primary endpoint was the proportion of women who maintained menstrual blood loss volume <80 mL through week 76 (week 24 of randomized withdrawal study). Secondary endpoints included time to menstrual blood loss volume ≥80 mL, proportion of women who maintained a menstrual blood loss volume of <80 mL through week 104 (over the 52-week randomized treatment period), the proportion of women who achieved or maintained amenorrhea at week 76 at the end of treatment, and the change in Uterine Fibroid Symptom–Quality of Life Bleeding and Pelvic Discomfort Scale and symptom severity scores. Analyses were performed for the modified intent-to-treat population, including all randomized women who received ≥1 dose of the study drug.

Of the 229 randomized women (relugolix combination therapy, n=115; placebo, n=114), 228 received the study drug and 175 (76.7%) completed the randomized withdrawal study. Through week 76, 78.4% of women on relugolix combination therapy maintained menstrual blood loss volume <80 mL vs 15.1% in the placebo group (difference, 63.4%; 95% confidence interval, 52.9%–73.9%; P<.0001). At week 104, 69.8% of women on relugolix combination therapy maintained menstrual blood loss volume <80 mL vs 11.8% in the placebo group (difference, 58.0%; 95% confidence interval, 47.0%–69.1%; P<.0001). Through week 104, 88.3% of women on placebo relapsed with heavy menstrual bleeding (median time to relapse, 5.9 weeks). Among the 89 women in the placebo group who relapsed and received open-label rescue treatment, 87 women responded to relugolix combination therapy with a menstrual blood loss volume <80 mL. The proportion of women who achieved or maintained amenorrhea were 57.4% vs 13.3% at week 76 (difference, 44.1%; 95% confidence interval, 33.10%–55.1%; P<.0001) and 58.3% vs 10.6% at week 104 (difference, 47.6%; 95% confidence interval, 37.0%–58.3%; nominal P<.0001) for relugolix combination therapy and the placebo group, respectively. Relugolix combination therapy was generally well tolerated; no new safety signals were identified, and the adverse event profile over the second year was consistent with that reported through the first year of treatment. Bone mineral density remained stable in women who received relugolix combination therapy from week 52 to week 104. In women continuously treated with relugolix combination therapy up to 2 years, bone mineral density was generally preserved.

After 2 years of treatment with relugolix combination therapy, there was evidence of durability of the effect in maintaining low menstrual blood loss volume in women with symptomatic uterine fibroids. Most women had return of heavy menstrual bleeding and associated symptoms after treatment cessation, which improved upon retreatment with relugolix combination therapy. Relugolix combination therapy was well tolerated, the adverse event profile remained consistent, and the mean bone mineral density was generally preserved through 2 years of treatment.