FDA Makes Pfizer, Myovant Wait on Approval For Myfembree

FDA has decided to extend the review period of Myfembree. (Courtesy of Sarah Silbiger/Getty Images)

FDA has decided to extend the review period of Myfembree. (Courtesy of Sarah Silbiger/Getty Images)

Less than one month after the U.S. Food and Drug Administration raised concerns about the supplemental New Drug Application for Pfizer and Myovant Sciences’ Myfembree (relugolix), the regulatory agency has extended the review period to Aug. 6. The initial approval date was Friday.

Myovant Sciences, one of the Vants forged by Roivant Sciences, and Pfizer have been seeking approval for Myfembree for the management of moderate to severe pain associated with endometriosis. In an announcement this morning, the companies said the extension was added to the review period in order to provide the regulatory agency with time to review additional information they had sent to support the sNDA.

Juan Camilo Arjona Ferreira, chief medical officer of Myovant Sciences, said the companies remain confident in the clinical profile of Myfembree and in the medication’s potential to become a therapeutic option for the management of endometriosis-associated pain. Ferreira said Myovant and Pfizer will work closely with the FDA to support the ongoing review of the sNDA.

Last month, the FDA issued a notice to both companies that it had found “deficiencies” that would preclude any potential discussion of labeling or post-marketing requirements at the time. What those deficiencies were had not been disclosed.

However, it appears that the companies had relevant information that would allow the FDA to move forward with the review, rather than issue a Complete Response Letter, as had been expected last month. As a result, shares of Myovant jumped nearly 10% in premarket trading as investors responded to the news.

Myfembree Targets Which Disease?

Myfembree was approved last year for the treatment of heavy menstrual bleeding associated with uterine fibroids in premenopausal women. The companies hope to expand that approval to include the management of pain associated with endometriosis, a condition in which endometrial tissue is found outside of the uterine cavity.

Endometriosis can lead to the development of disruptive symptoms such as painful periods, fatigue, pain in the lower back and abdomen, heavy menstrual bleeding and even painful or difficult sexual intercourse. It is estimated that almost 200 million women across the globe suffer from symptoms of endometriosis. In the United States, there are estimated to be around 7.5 million premenopausal women with endometriosis. Pfizer and Myovant noted that a diagnosis of endometriosis can take between four and 11 years.

The sNDA for Myfembree was supported by data from the Phase III Spirit program. That program included the Spirit 1 and Spirit 2 studies that involved more than 1,200 women with pain associated with endometriosis. In 2020, the companies reported that Myfembree hit the mark in its co-primary endpoints as well as its secondary endpoints in the SPIRIT 1 study.

The drug generated clinically-meaningful pain reductions for 74.5% of women with dysmenorrhea (menstrual pain) and 58.5% of women with non-menstrual pelvic pain compared to placebo. In the SPIRIT 2 study, Myfembree demonstrated a 75.2% response rate for dysmenorrhea and a 66% response rate for non-menstrual pelvic pain compared to a placebo.

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