Relugolix, an oral gonadotropin-releasing hormone receptor antagonist, reduces endometriosis-associated pain compared with leuprorelin in Japanese women: a phase 3, randomized, double-blind, noninferiority study

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Tasuku Harada, M.D., Ph.D., Yutaka Osuga, M.D., Ph.D., Yusuke Suzuki, M.Pharm., Masaki Fujisawa, Ph.D., Motoko Fukui, D.V.M. , Jo Kitawaki, M.D., Ph.D.



To evaluate the efficacy and safety of 40-mg relugolix (REL) compared with those of leuprorelin (LEU) in women with endometriosis-associated pain.


Phase 3, multicenter, randomized, double-blind, double-dummy, active-controlled study in Japanese patients.


Hospitals and clinics.


Women aged ≥20 years with regular menstrual cycles (25–38 days) experiencing endometriosis or ovarian endometrioma and reporting pelvic pain.


In the REL group, 40 mg of REL was orally administered once a day for 24 weeks. In the LEU group, 3.75 or 1.88 mg of LEU was subcutaneously injected every 4 weeks for 24 weeks.

Main Outcome Measure(s)

The primary endpoint was the change in the maximum visual analog scale score for pelvic pain from baseline until 28 days before the end of treatment.


Changes in the maximum visual analog scale score were −52.6 ± 1.3 for REL and −57.5 ± 1.4 for LEU. Ovarian endometrioma decreased by 12.26 ± 17.52 cm3 for REL and 14.10 ± 18.81 cm3 for LEU. Drug-related treatment emergent adverse events with an incidence of >10% for both groups were hot flush, metrorrhagia, headache, and genital hemorrhage. Discontinuations from treatment emergent adverse events were 2.9% for REL and 4.3% for LEU.


Relugolix was noninferior to LEU for treating endometriosis-associated pelvic pain. Safety profiles of both medications were comparable, although menses returned earlier in patients taking REL, a huge benefit for women who plan to conceive after treatment.

Clinical Trial Registration Number NCT03931915.

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.