FDA Accepts sNDA for Myfembree as Treatment for Heavy Menstrual Bleeding

The study has met its primary endpoint, with approximately 78.4% of women who continued taking the drug achieving the sustained responder rate through week 76.

The FDA has accepted a supplemental new drug application (sNDA) for relugolix 40 mg, estradiol 1 mg, and norethindrone acetate 0.5 mg (Myfembree; Myovant Sciences, Pfizer) for review.

The sNDA proposed updates to the United States Prescribing Information based on efficacy and safety data from the phase 3 LIBERTY randomized withdrawal study.

The study included women who were premenopausal with heavy menstrual bleeding associated with uterine fibroids for up to 2 years.

The FDA has set a target action date of January 29, 2023, for this sNDA under the Prescription Drug User Fee Act.

“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,” Juan Camilo Arjona Ferreira, MD, chief medical officer of Myovant Sciences, said in a statement. “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.”

Individuals who completed the 24-week pivotal LIBERTY 1 and LIBERY 2 studies were offered the option to receive Myfembree for an additional 28 weeks as part of an open-label extension study.

After the completion of either study and the open-label extension studies, women who met the definition of responder, which was menstrual blood loss less than 80 mL and a reduction from the pivotal study baseline greater than 50%, could participate in an additional 52-week randomized withdrawal study.

The withdrawal study was designed to provide 2-year efficacy and safety data on Myfembree and to evaluate the need for maintenance therapy.

Women who entered the randomized withdrawal study were re-randomized to receive Myfembree or the placebo for an additional 52 weeks, with the primary endpoint at 76 weeks.

The LIBERTY randomized withdrawal study met its primary endpoint with approximately 78.4% of women who continued Myfembree achieving the sustained responder rate through week 76 compared with about 15.1% of women who discontinued treatment and initiated the placebo at week 52.

Investigators reported that all 3 key secondary endpoints in the LIBERTY randomized withdrawal study were also achieved, including the amenorrhea rate, the sustained responder rate through week 104, and time to relapse of heavy menstrual bleeding.

Additionally, bone mineral density remained stable in women who received Myfembree in the randomized withdrawal study. The bone mineral density was maintained through 2 years in the subset of women continuously treated with Myfembree.

The incidence of adverse events (AEs) over 1 additional year of treatment was consistent with those observed in prior studies, and no new safety signals were observed.

In both LIBERTY studies, the most common AEs were alopecia, decreased libido, hot flush, hyperhidrosis, and uterine bleeding.

In 2021, Myfembree was approved in the United States for the management of heavy menstrual bleeding associated with uterine fibroids in women who are premenopausal with a treatment duration of up to 24 months.

Reference

Myovant Sciences and Pfizer announce FDA Acceptance of supplemental new drug application for Myfembree. Pfizer. News release. June 2, 2022. Accessed June 3, 2022. https://www.pfizer.com/news/press-release/press-release-detail/myovant-sciences-and-pfizer-announce-fda-acceptance-1