Myovant Sciences (NYSE: MYOV) and Pfizer Inc. (NYSE: PFE) today announced that the Phase 3 SPIRIT long-term extension study of the investigational once-daily relugolix combination therapy (relugolix 40 mg plus estradiol 1.0 mg and norethindrone acetate 0.5 mg) in women with endometriosis reported clinically meaningful reductions in dysmenorrhea (menstrual pain) and non-menstrual pelvic pain over one year (52 weeks) with minimal and stable bone mineral density loss. The data are consistent with the efficacy and safety profile observed through 24 weeks in the Phase 3 SPIRIT 1 and SPIRIT 2 studies. These results will be included in the New Drug Application to the U.S. Food and Drug Administration for relugolix combination tablet for the treatment of women with endometriosis, anticipated to be submitted in the first half of 2021.

“Given the debilitating impact that endometriosis can have on women in their daily lives, often over many years, we need non-invasive and long-term treatment options,” said Linda Giudice, M.D., Ph.D., Distinguished Professor in the Center for Reproductive Sciences at the University of California, San Francisco (UCSF) and SPIRIT Program Steering Committee Member. “The one-year data from the Phase 3 SPIRIT extension study offers promising evidence that relugolix combination therapy has the potential to significantly and durably reduce pain in women with endometriosis, while remaining well tolerated.”

In the SPIRIT long-term extension study, 84.8% and 73.3% of women receiving relugolix combination therapy over one year achieved clinically meaningful pain reductions in dysmenorrhea and non-menstrual pelvic pain, respectively. On average, women reported an 82.8% reduction on the 11-point Numerical Rating Scale (0-10) for dysmenorrhea from 7.4 (severe pain) to 1.3 (mild pain) over one year.

“Building on the strength of our one-year data of relugolix combination therapy in uterine fibroids, we are pleased by the one-year safety and efficacy data in women with endometriosis, which further our vision for a one pill, once-a-day treatment option suitable for long-term use in both diseases,” said Juan Camilo Arjona Ferreira, M.D., Chief Medical Officer of Myovant Sciences, Inc. “We look forward to submitting a New Drug Application for this potential new treatment for women with endometriosis in the first half of this year.”

“Endometriosis is a common and painful condition, which impacts approximately 10 percent of women during their reproductive lifetime,” said James Rusnak, M.D., Ph.D., Senior Vice President, Chief Development Officer, Internal Medicine and Hospital, Global Product Development at Pfizer. “We believe the results from the one-year extension study show the encouraging potential of relugolix combination therapy to evolve the treatment paradigm for women with endometriosis.”

Bone mineral density remained stable through Week 52 in women treated with relugolix combination therapy after minimal, non-clinically meaningful bone loss through Week 24. The incidence of adverse events over one year was consistent with that observed in SPIRIT 1 and SPIRIT 2, with no new safety signals observed. The most commonly reported adverse events in at least 10% of women treated with relugolix combination therapy were headache, nasopharyngitis, and hot flashes. There was one pregnancy reported in the relugolix combination therapy group (n = 278).

Data from SPIRIT 1 and SPIRIT 2 studies were previously presented at the American Society for Reproductive Medicine (ASRM) 2020 Virtual Congress. Complete results from the SPIRIT long-term extension study will be submitted for presentation at a future scientific meeting and publication in a medical journal.

In December 2020, Myovant and Pfizer entered into a collaboration for the development and commercialization of relugolix in oncology and women’s health in the U.S. and Canada. Under the terms of the agreement, Myovant and Pfizer will jointly develop and commercialize ORGOVYXTM (relugolix) in advanced prostate cancer and, if approved, relugolix combination tablet (relugolix 40 mg, estradiol 1.0 mg, and norethindrone acetate 0.5 mg) in uterine fibroids and endometriosis.

About the Phase 3 SPIRIT Program in Endometriosis
The Phase 3 clinical program for endometriosis consists of two multinational, replicate pivotal clinical studies (SPIRIT 1 and SPIRIT 2) of relugolix combination therapy (relugolix 40 mg plus estradiol 1.0 mg and norethindrone acetate 0.5 mg) in over 1,200 women with pain associated with endometriosis. Women received treatment either with relugolix combination therapy for 24 weeks, relugolix 40 mg once daily monotherapy for 12 weeks followed by relugolix combination therapy once daily for an additional 12 weeks, or placebo once daily for 24 weeks. Eligible women who completed the SPIRIT 1 or SPIRIT 2 studies were offered the opportunity to enroll in an active treatment extension study in which all women receive relugolix combination therapy for an additional 80-week period, resulting in a total treatment period of up to 104 weeks, designed to evaluate the safety and sustained efficacy of longer-term treatment.

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