FDA accepts Myfembree sNDA for bleeding associated with uterine fibroids

Myovant Sciences and Pfizer announced the US Food and Drug Administration (FDA) has accepted to review the supplemental New Drug Application (sNDA) for Myfembree (relugolix, estradiol, and norethindrone acetate; Myovant Sciences and Pfizer) for the potential treatment of heavy menstrual bleeding associated with uterine fibroids in premenopausal women for up to 2 years. Currently, Myfembree is approved for the management of heavy menstrual bleeding associated with uterine fibroids for up to 24 months in premenopausal women.¹

The sNDA suggests updates be made to the medication’s prescribing information, which is based on efficacy and safety data from the recent phase 3 LIBERTY randomized withdrawal study (RWS). Under the Prescription Drug User Fee Act (PDUFA), the FDA has set an estimated action date of January 29, 2023, for this sNDA, according to a company press release.¹

“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.”

Study participants from the 24-week LIBERTY 1 and 2 studies were offered to opt into an additional 28-week open-label extension study. Following competition of both the LIBERTY 1 and 2 studies, as well as the 28-week extension study, women who fell under the responder category (menstrual blood loss < 80 mL and a reduction from pivotal study baseline > 50%), could also opt into an additional 52-week RWS study. The RWS study was focused on delivering 2 years’ worth of efficacy and safety data on Myfembree, as well as investigate the need for maintenance therapy.

In the phase 3 RWS study, responders were randomized to receive either placebo or Myfembree for 52 weeks (N = 229). The study met its primary end point with participants who received Myfembree (78.4%) achieving the sustained responder rate (menstrual blood loss < 80 mL) through Week 76 vs patients (15.1%) who discontinued treatment and initiated placebo at Week 52 (p < 0.0001).

The 3 secondary end points were also achieved, including sustained responder rate through Week 104, time to relapse of heavy menstrual bleeding, and amenorrhea rate (all p < 0.0001).

As for safety data, bone mineral density was observed as stable and was maintained through 2 years in patients who continuously received Myfembree (N = 31). Additionally, adverse events were consistent with prior studies and no new safety signals were observed, according to the press release.

“Data from the Myfembree RWS supports our mission to improve care for women living with uterine fibroids,” said James Rusnak, MD, PhD, senior vice president, chief development officer, internal medicine and hospital, global product development at Pfizer. “We look forward to the FDA’s review of the application and potential updates to the Myfembree prescribing information based on these data.”

Reference

1. Myovant Sciences and Pfizer announce FDA acceptance of supplemental new drug application for Myfembree. Myovant Sciences ltd. Published June 2, 2022. Accessed June 2, 2022. https://investors.myovant.com/news-releases/news-release-details/myovant-sciences-and-pfizer-announce-fda-acceptance-0/