Bleeding Patterns With Relugolix Combination Therapy in Women With Endometriosis-Associated Pain [ID: 1345374]

INTRODUCTION: Relugolix combination therapy (Relugolix-CT: relugolix 40 mg, estradiol 1 mg, norethindrone acetate 0.5 mg) significantly improved endometriosis-associated pain versus placebo in the SPIRIT 1&2 studies. Efficacy was maintained over 104 weeks in the long-term extension (LTE) study. Bleeding patterns in women treated up to 104 weeks with Relugolix-CT are reported. METHODS: SPIRIT 1&2 were IRB-approved phase 3, 24-week, randomized studies of Relugolix-CT, delayed Relugolix-CT (relugolix 40 mg monotherapy followed by Relugolix-CT; 12 weeks each), or placebo in premenopausal women (age 18–50 years) with moderate-to-severe endometriosis-associated pain. Eligible women completing SPIRIT 1&2 could enroll in the open-label LTE with once-daily Relugolix-CT. Bleeding days per cycle and bleeding patterns were recorded on eDiaries. Amenorrhea was defined as no bleeding over 28 consecutive days. RESULTS: Of 1,261 women originally randomized, 501 completed week 104. Baseline demographics and characteristics were balanced across treatment groups. The proportion of women achieving amenorrhea increased over time: 74.4% (95% CI 68.8–79.4) at week 24, and 82.3% (95% CI 74.6–88.4) at week 104. The average number of bleeding days per cycle (standard deviation) decreased over time from 5.8 (2.4) at baseline to 1.2 (3.3) at week 104. The number of heavy or extremely heavy bleeding days decreased from 1.9 at baseline to 0.0 at week 104. CONCLUSION: Treatment with Relugolix-CT in women with endometriosis-associated pain resulted in high rates of amenorrhea and complete elimination of heavy bleeding, thus demonstrating sustained benefit through 2 years. Findings may support patient counseling.