Experimental Drug Stops Hot Flashes Without Hormones

A new era of menopause treatment looks to be on the horizon. This week, drugmaker Bayer published the results of two successful Phase III trials testing its experimental drug elinzanetant as a treatment for hot flashes. The drug is now poised to become the first non-hormonal medication of its kind approved in the world.

Hot flashes and night sweats are common symptoms of menopause, affecting around 80% of women in their lifetime. Formally known as vasomotor symptoms, hot flashes are characterized by sudden bouts of warmth, redness, and sweating, typically around the face, neck, and chest (night sweats are similar, but occur at night and while sleeping). These episodes can be deeply uncomfortable, and more serious cases are thought to raise the risk of poor sleep and depression. Though hot flashes do decline over time, they often last for at least two years, and some women will experience them for a decade or longer, according to the Mayo Clinic.

Historically, hot flashes have been effectively treated with hormone therapy, which aims to replace the levels of estrogen and progesterone that decline with menopause. Starting in the late 1990s, however, large-scale trials began to show that hormone therapy could potentially raise the risk of other health problems, including heart disease, breast cancer, and stroke, in menopausal women—results that soon led to a large and sustained drop-off in the treatment. Later studies and more recent analyses of the data have found that these risks may have been overstated and can be safely mitigated. Organizations like the North American Menopause Society currently state that the benefits of hormonal treatment for hot flashes outweigh any potential harms for most women who start therapy before age 60 and/or within ten years of their last period. But hormone therapy remains much less popular than before, and there are some women who have a higher risk of complications from it, such as those with a history of breast cancer.

Women unwilling or unable to use hormones for their hot flashes have had limited other options to date, such as low doses of certain SSRIs. But in the early 2010s, scientists finally started to unravel some of the mechanisms underlying hot flashes. They discovered that a group of neurons that produced kisspeptin, neurokinin B (NKB), and dynorphin (known as KNDy neurons) were pivotal in causing the flushing associated with low estrogen levels. Later studies found that blocking the activity of some receptors on these cells could safely reduce hot flashes. And in May 2023, the Food and Drug Administration approved Astellas Pharma’s fezolinetant, the first drug that treats hot flashes by blocking one of these receptors, NK3.

Bayer’s elinzanetant blocks both NK3 and NK1 receptors, a dual-action design that scientists have hoped would not only reduce hot flashes but also the sleeping problems often associated with menopause. In the largest Phase III trials of the drug, published Thursday in the journal JAMA, those hopes look to have been validated.

The studies involved over 700 women in their 40s and 50s diagnosed with moderate to severe hot flashes, who were randomized to receive elinzanetant or a placebo. Across both trials, researchers found that women taking elinzanetant (a once-daily pill) experienced a significant reduction in hot flashes relative to controls. By the end of the studies, 26 weeks later, over 80% of women on the drug saw a more than 50% reduction in symptoms, including women who switched to the drug 12 weeks into their trial. Participants also reported fewer sleep disturbances than women taking a placebo, and they reported a higher increase in their menopause-related quality of life. Elinzanetant appeared to be safe as well, with the most common adverse events (compared to placebo) in those taking the drug being headaches and fatigue.

“Elinzanetant has the potential to provide a well-tolerated and efficacious nonhormonal treatment option to address the unmet health needs of many menopausal individuals with moderate to severe [hot flashes],” the researchers of the JAMA paper wrote.

The results follow equally promising findings from the company’s other Phase III trial of elinzanetant, announced earlier this March. And the company is now planning to submit data from all three studies to regulators to secure the drug’s approval as a treatment for moderate to severe hot flashes—an approval that should be in the bag, barring any major surprises.

As important as the arrival of these drugs is, though, there is the thorny issue of cost. Fezolinetant’s list price is currently around $550 a month, and it has received limited insurance coverage to date, according to Forbes. These drugs could eventually be widely covered, especially as more enter the market, but for now, there is the chance that many eligible patients will not be able to afford them.