Effect of Mifepristone vs Placebo for Treatment of Adenomyosis With Pain Symptoms

Importance: Adenomyosis is a common chronic gynecological disorder, and its treatment is an unmet need. New therapies need to be developed. Mifepristone is being tested for adenomyosis treatment. Objective: To determine whether mifepristone is effective and safe for adenomyosis treatment. Design, Setting, and Participants: This multicenter, placebo-controlled, double-blind randomized clinical trial was conducted in 10 hospitals in China. In total, 134 patients with adenomyosis pain symptoms were enrolled. Trial enrollment began in May 2018 and was completed in April 2019, and analyses were conducted from October 2019 to February 2020. Interventions: Participants were randomized 1:1 to receive mifepristone 10 mg or placebo orally once a day for 12 weeks. Main Outcomes and Measures: The primary end point was the change in adenomyosis-associated dysmenorrhea intensity, evaluated by the visual analog scale (VAS) after 12 weeks of treatment. Secondary end points included the change in menstrual blood loss, increased level of hemoglobin in patients with anemia, CA125 level, platelet count, and uterine volume after 12 weeks of treatment. Safety was assessed according to adverse events, vital signs, gynecological examinations, and laboratory evaluations. Results: In total, 134 patients with adenomyosis and dysmenorrhea were randomly assigned, and 126 patients were included in the efficacy analysis, including 61 patients (mean [SD] age, 40.2 [4.6] years) randomized to receive mifepristone and 65 patients (mean [SD] age, 41.7 [5.0] years) randomized to received the placebo. The characteristics of the included patients at baseline were similar between groups. The mean (SD) change in VAS score was -6.63 (1.92) in the mifepristone group and -0.95 (1.75) in the placebo group (P < .001). The total remission rates for dysmenorrhea in the mifepristone group were significantly better than those in the placebo group (effective remission: 56 patients [91.8%] vs 15 patients [23.1%]; complete remission: 54 patients [88.5%] vs 4 patients [6.2%]). All the secondary end points showed significant improvements after mifepristone treatment for menstrual blood loss, hemoglobin (mean [SD] change from baseline: 2.13 [1.38] g/dL vs 0.48 [0.97] g/dL; P < .001), CA125 (mean [SD] change from baseline: -62.23 [76.99] U/mL vs 26.89 [118.70] U/mL; P < .001), platelet count (mean [SD] change from baseline: -28.87 [54.30]×103/µL vs 2.06 [41.78]×103/µL; P < .001), and uterine volume (mean [SD] change from baseline: -29.32 [39.34] cm3 vs 18.39 [66.46] cm3; P < .001). Safety analysis revealed no significant difference between groups, and no serious adverse events were reported. Conclusions and Relevance: This randomized clinical trial showed that mifepristone could be a new option for treating patients with adenomyosis, based on its efficacy and acceptable tolerability. Trial Registration: ClinicalTrials.gov Identifier: NCT03520439.