Relugolix demonstrates positive phase 3 data as combination therapy for endometriosis pain


Results suggest the potential of this oral therapy to address the unmet clinical need for long-term medical treatment for endometriosis.

Myovant Sciences and Pfizer recently announced positive results of the phase 3 SPIRIT 1 and SPIRIT 2 studies evaluating the investigational combination therapy of relugolix, estradiol and norethindrone acetate (Myfembree; Myovant and Pfizer) for moderate to severe endometriosis-associated pain.1

In both studies, 75% of women using the once daily relugolix combination therapy experienced a significant reduction in dysmenorrhea, compared to 27% and 30% of women in the placebo groups at Week 24, respectively (both p < 0.0001). Relugolix combination therapy also significantly reduced non-menstrual pelvic pain in 59% and 66% of women, compared to 40% and 43% in the placebo groups (p <0.0001).2

In SPIRIT 1 and 2, the relugolix combination therapy group also showed reductions in dyspareunia and opioid use compared to the placebo groups. Additionally, more women undergoing relugolix combination therapy were opioid free at Week 24 compared with placebo (86% and 82% vs 76% and 66%, respectively).2

The most frequently reported adverse events by women in both the relugolix combination therapy and placebo groups included headaches, nasopharyngitis, and hot flashes.

Currently, the relugolix combination tablet (relugolix 40 mg, estradiol 1.0 mg, and norethindrone acetate 0.5 mg) is available in the United States as Myfembree for the management of uterine fibroid-related heavy menstrual bleeding in premenopausal women.

“The data [from SPIRIT 1 and 2] underscore the value relugolix combination therapy may provide as a potential new treatment option for women with endometriosis-associated pain,” said Juan Camilo Arjona Ferreira, MD, chief medical officer of Myovant Sciences.1

According to the studies’ authors, “this oral therapy has the potential to address the unmet clinical need for long-term medical treatment for endometriosis, reducing the need for opioid use or repeated surgical treatment.”2

Data from SPIRIT 1, SPIRIT 2, and an open-label extension study were included in a supplemental New Drug Application for the relugolix combination tablet for the management of moderate to severe endometriosis pain with a target Prescription Drug User Fee Act of August 6, 2022.


  1. Myovant Sciences and Pfizer Announce Publication in The Lancet of Phase 3 SPIRIT 1 and SPIRIT 2 Studies of Once-Daily Relugolix Combination Therapy in Women With Endometriosis-Associated Pain | Myovant Sciences Ltd. Myovant Sciences Ltd. Published 2022. Accessed June 22, 2022.
  2. Giudice LC, As-Sanie S, Arjona Ferreira JC, et al. Once daily oral relugolix combination therapy versus placebo in patients with endometriosis-associated pain: two replicate phase 3, randomised, double-blind, studies (SPIRIT 1 and 2). The Lancet. 2022;399(10343):2267-2279. doi:10.1016/s0140-6736(22)00622-5
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