Originally published by our sister publication Pain Medicine News

The FDA approved relugolix 40 mg, estradiol 1 mg and norethindrone acetate 0.5 mg (Myfembree, Myovant and Pfizer) as a once-daily therapy for the management of moderate to severe pain associated with endometriosis in premenopausal women, with a treatment duration of up to 24 months. 

The approval is supported by one-year data from the phase 3 SPIRIT program, which included two 24-week multinational clinical studies (SPIRIT 1 and SPIRIT 2) in more than 1,200 women with pain associated with endometriosis, as well as the first 28 weeks of an open-label extension study to assess its long-term use. Overall, the studies showed the relugolix combination reduced menstrual pain and non-menstrual pelvic pain with a loss of mean bone mineral density of less than 1% from baseline through one year of treatment (Lancet 2022;399[10343]:2267-2279).

SPIRIT 1 and SPIRIT 2 met their co-primary end points, with 75% of women in the relugolix group in both studies achieving a clinically meaningful reduction in dysmenorrhea compared with 27% and 30% of women in the placebo groups at week 24, respectively (both P<0.0001). For non-menstrual pelvic pain, treatment with the relugolix combination demonstrated a clinically meaningful reduction in pain in 59% and 66% of women, compared with 40% and 43% of women in the placebo groups (P<0.0001). Adverse reactions occurring in at least 3% of women treated with the relugolix combination and greater than placebo were headache, vasomotor symptoms, mood disorders, abnormal uterine bleeding, nausea, toothache, back pain, decreased sexual desire and arousal, arthralgia, fatigue, and dizziness.

The open-label extension study for eligible women who completed either SPIRIT 1 or SPIRIT 2 showed mean bone mineral density loss of less than 1% from baseline through one year of treatment; some patients (19.7%) had losses of more than 3%. Annual bone density measurement is recommended while treating women for endometriosis.

“The data from the SPIRIT studies showed the clinical benefit that relugolix combination therapy can have on moderate to severe pain associated with endometriosis and how it can impact patients,” said Linda Giudice, MD, PhD, the Distinguished Professor at the University of California, San Francisco, and chair of the SPIRIT Program Steering Committee. “This newly approved option for patients with pain from endometriosis offers the convenience of one pill taken once daily with a mean change in bone mineral density of higher than 1% that did not appear to worsen at 12 months of treatment; however, monitoring is recommended.”

The relugolix combination also is approved for heavy menstrual bleeding associated with uterine fibroids in premenopausal women.

Based on a press release from Pfizer.