Astellas files menopause drug fezolinetant in US, setting up Feb verdict

Astellas remains on course to be the first drugmaker to bring a new non-hormonal therapy for symptoms of menopause to market, after the FDA started a review of its orally-active neurokinin-3 (NK3) receptor antagonist fezolinetant.

The US regulator is scheduled to complete its review of fezolinetant as a treatment for moderate to severe vasomotor symptoms (VMS) of menopause, such as hot flushes and night sweats, by 22 February next year, said the Japanese pharma.

Astellas has high hopes for the new drug, so much so that it has used a priority review voucher to reduce the FDA's review time from ten months to six, which resulted in a 13.1 billion yen ($97 million) charge as an R&D expense in its fiscal first quarter.

VMS are reported by up to 80% of women at some point during menopause and is the leading cause for seeking medical attention during this phase of their lives. Around a third of women report severe VMS, which can last ten years or more after the last menstrual period.

Treatment with VMS currently relies on hormonal replacement therapy (HRT) as well as less commonly other drugs like selective serotonin reuptake inhibitor (SSRI) antidepressants, which all have trade-offs between safety and efficacy.

In clinical trials, fezolinetant was shown to significantly reduce the frequency and severity of VMS compared to placebo over periods of up to 52 weeks.

The start of the FDA appraisal, and the shortened review time, keep Astellas ahead of its closest rival in the new category, Germany's Bayer, which is developing an NK1,3 inhibitor called elinzanetant for menopausal VMS.

Elinzanetant is in a phase 3 programme called OASIS that is following a similar pattern to Astellas' studies with a pair of placebo-controlled studies and a long-term safety assessment.

Initial results are due towards the end of this year or in early 2023, and Bayer has previously said it thinks its drug could become a $1 billion blockbuster. It acquired elinzanetant as part of its takeover of UK biotech KaNDy Therapeutics in 2020.

The fezolinetant filing "brings us one step closer to advancing care for women in the US who experience VMS," said Astellas' head of development Ahsan Arozullah.

"We look forward to the FDA's review of our application, and the potential to offer a first-in-class non-hormonal treatment option to reduce the frequency and severity of moderate to severe VMS associated with menopause."

Astellas acquired fezolinetant as part of its 2017 takeover of Ogeda for €500 million (at the time equivalent to around $550 million) upfront plus €300 million in potential milestones.