FDA to Review Data on Long-Term Use of Myfembree for Uterine Fibroids

The study enrolled women who completed the 24-week LIBERTY 1 and 2 studies and the 28-week open-label extension studies, and who met the definition of a responder.

The Food and Drug Administration (FDA) has accepted for review the supplemental New Drug Application (sNDA) for Myfembree® (relugolix 40mg, estradiol 1mg, and norethindrone acetate 0.5mg). The sNDA proposes to update the prescribing information to include long term data from a study evaluating Myfembree in premenopausal women with heavy menstrual bleeding associated with uterine fibroids.

The sNDA submission is supported by data from the phase 3 LIBERTY randomized withdrawal study (ClinicalTrials.gov Identifier: NCT03751124), which evaluated the long-term efficacy and safety of Myfembree for an additional 52 weeks. Study participants had completed either the 24-week LIBERTY 1 trial (ClinicalTrials.gov Identifier: NCT03049735) or the LIBERTY 2 (ClinicalTrials.gov Identifier: NCT03103087) trial, as well as the 28-week open-label extension study.

Women who met the definition of a responder, defined as a menstrual blood loss of less than 80mL and a 50% or greater reduction from baseline in menstrual blood loss volume, were re-randomized to receive either Myfembree or placebo. Results showed that 78.4% of women treated with Myfembree achieved the sustained responder rate through week 76 compared with 15.1% of women who discontinued treatment and initiated placebo at week 52 (P <.0001). The study also met 3 key secondary endpoints: sustained responder rate through week 104, time to relapse of heavy menstrual bleeding, and amenorrhea rate (all P <.0001).

The safety profile of Myfembree over an additional 52 weeks was consistent with that seen in previous studies, with no new safety signals identified. Additionally, in a subset of women continuously treated with Myfembree (n=31), bone mineral density remained stable through 2 years.

“Heavy menstrual bleeding is the most common symptom affecting women with uterine fibroids that can impact their daily life and activities over a long period of time,” said Juan Camilo Arjona Ferreira, MD, Chief Medical Officer of Myovant Sciences, Inc. “We are pleased to submit these study results to the FDA as they show the value Myfembree can potentially have on treating women’s uterine fibroid symptoms long term.”

A Prescription Drug User Fee Act (PDUFA) target date of January 29, 2022 has been set for the application.

Myfembree is currently approved for the management of heavy menstrual bleeding associated with uterine leiomyomas (fibroids) in premenopausal women. 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.


Myovant Sciences and Pfizer announce FDA acceptance of supplemental New Drug Application for Myfembree®. News release. Myovant Sciences and Pfizer Inc. Accessed June 2, 2022. https://www.globenewswire.com/news-release/2022/06/02/2454992/0/en/Myovant-Sciences-and-Pfizer-Announce-FDA-Acceptance-of-Supplemental-New-Drug-Application-for-MYFEMBREE.html