Endocrine Abstracts

Objective: The objective of this Phase 2 study was to evaluate the safety of relugolix when administered for 24 weeks in women with EM-associated pain. Efficacy was exploratory assessed using leuprorelin as a reference.

Design: This was an open-label extension study evaluating safety of 3 doses (10 mg, 20 mg, and 40 mg) of relugolix administered orally once daily for a total of 24 weeks in women with EM-associated pain, who had participated in a preceding 12-week study.

Materials and methods: Premenopausal women with EM-associated pain who completed a preceding 12-week study and were eligible to continue for an additional 12-week treatment were enrolled. The primary endpoint was the safety including assessment of change in bone mineral density using dual energy x-ray absorptiometry. Analysis sets were defined as all patients who were administered the study drug.

Results: Among the randomized patients in the preceding study (N=487), 397 were enrolled in this extension study; 77 to placebo, 78 to 89 to relugolix groups, and 69 to leuprorelin. Baseline characteristics were similar between randomized patients and all patients who entered the extension study. The incidences of adverse events including metrorrhagia, menorrhagia, and hot flush in the relugolix 40 mg group were similar to those in the leuprorelin group. Dose-dependent bone density loss was observed with relugolix treatment, with the relugolix 40 mg result consistent with the leuprorelin result. The change from baseline in mean visual analogue scale score for pelvic pain (in mm) during the last 4 weeks of treatment period was −3.222 in the placebo group, −6.849, −9.032, and −11.924 in relugolix 10 mg, 20 mg and 40 mg groups, respectively, and −12.552 in the leuprorelin group. Estradiol levels decreased with increasing dose of relugolix and were maintained below the postmenopausal levels throughout the 24-week relugolix 40 mg treatment period.

Conclusion: Treatment with relugolix for 24 weeks was generally well tolerated and demonstrated similar pelvic pain reduction as leuprorelin in women with EM. Relugolix, a once-daily oral nonpeptide GnRH receptor antagonist, demonstrated similar benefit to injectable leuprorelin in this Phase 2 study.