Myfembree® (relugolix, estradiol, and norethindrone acetate) is now available for the management of heavy menstrual bleeding associated with uterine leiomyomas (fibroids) in premenopausal women.
Myfembree is a combination of relugolix, a gonadotropin-releasing hormone receptor antagonist, estradiol, an estrogen, and norethindrone acetate, a progestin. The approval was based on data from 2 randomized, double-blind, placebo-controlled studies: LIBERTY 1 (ClinicalTrials.gov Identifier: NCT03049735) and LIBERTY 2 (ClinicalTrials.gov Identifier: NCT03103087).
Findings from both studies showed that a statistically higher proportion of women treated with Myfembree met the primary endpoint achieving a menstrual blood loss volume of less than 80mL and at least a 50% reduction from baseline in menstrual blood loss volume during the last 35 days of the 24-week treatment period compared with placebo. Moreover, patients treated with Myfembree achieved a greater mean reduction in menstrual blood volume from baseline to week 24 compared with placebo.
Regarding safety, the most commonly reported adverse reactions included hot flush, hyperhidrosis or night sweats, uterine bleeding, alopecia, and decreased libido. Myfembree carries a Boxed Warning regarding the risk of thrombotic or thromboembolic disorders, especially in women at increased risk for these events. Myfembree may cause a decrease in bone mineral density in some patients; use should be limited to 24 months due to the risk of continued bone loss which may not be reversible.
Contraindications to treatment include high risk of arterial, venous thrombotic, or thromboembolic disorder, pregnancy, known osteoporosis, current or history of breast cancer or other hormone-sensitive malignancies, known hepatic impairment or disease, and undiagnosed abnormal uterine bleeding.
The product is supplied as a film-coated, fixed-dose combination tablet containing relugolix 40mg, estradiol 1mg, and norethindrone acetate 0.5mg in a 28-count bottle. Prior to initiating treatment, pregnancy should be excluded and hormonal contraceptives should be discontinued.
Myfembree [package insert]. Brisbane, CA: Myovant Sciences, Inc.; 2021.