Pfizer and Myovant’s endometriosis pain drug Myfembree gets another FDA nod
After months of delay in its decision, the FDA has given a green light to Pfizer and Myovant’s drug Myfembree for pain related endometriosis, a gynecological condition associated with moderate to severe pain, making it the drug’s second indication approval.
The FDA had earlier delayed its decision to review additional data it had requested from the companies regarding bone mineral density. The regulators had “identified deficiencies that preclude discussion of labeling and/or post-marketing requirements and commitment at this time,” the companies had said.
The approval comes after regulators noted data from two trials — SPIRIT 1 and SPIRIT 2 — which had more than 1,200 participants. Additionally, there was a 28-week open-label study to analyze the drug’s longer-term use.
Both SPIRIT 1 and 2 met their co-primary endpoints with 75% of women in the Myfembree group in both studies achieving a clinically meaningful reduction in menstrual cramps, compared with 27% and 30% of women in the placebo groups at Week 24, respectively (both p <0.0001), the companies said in a press statement.
For non-menstrual pelvic pain, treatment demonstrated a clinically meaningful reduction in pain in 59% and 66% of women, compared with 40% and 43% of women in the placebo groups (p < 0.0001), the companies added.
However, the improvements in pain were not free of side effects in some women. Adverse reactions occurring in at least 3% of women treated with Myfembree and greater than placebo were: headache, vasomotor symptoms, mood disorders, abnormal uterine bleeding, nausea, toothache, back pain, decreased sexual desire and arousal, arthralgia, fatigue and dizziness, the companies said.
Women who had completed participation on SPIRIT 1 or 2 were eligible for the open-label extension study. The data showed bone mineral density loss of less than 1% from baseline through one year of treatment, while 19.7% of patients had losses >3%.
The companies said the drug would be immediately available to patients with prescriptions from their healthcare providers.
The drug, which is a combination of relugolix 40 mg, estradiol 1 mg and norethindrone acetate 0.5 mg, is a one-pill, once-a-day therapy, to be taken for up to a year.
The drug, which was first approved in May 2021 to treat heavy menstrual bleeding associated with uterine fibroids, reeled in $4 million in net product revenues in the Swiss biopharma’s most recent quarter, the company said last month, noting 2,400 new patients began taking the treatment in the past three months.
In 2018, the FDA had approved AbbVie and Neurocrine Biosciences’ drug Orilissa (elagolix) for women with moderate to severe endometriosis pain. The drug reeled in $145 million in net revenue for all of 2021, AbbVie reported earlier this year.
Endometriosis is a condition where tissue lining the inner side of the uterus grows on other parts of the body, sometimes resulting in severe pain. The condition affects an estimated 2-10% percent of American women of childbearing age, according to Johns Hopkins Medicine.
An FDA nod means Myovant will receive a $100 million regulatory milestone from its partner Pfizer.