Elinzanetant Eases Hot Flashes in Women Taking Hormonal Therapy for Breast Cancer

If you’re having hot flashes because you’re taking hormonal therapy to treat or reduce the risk of developing breast cancer, a new treatment may be on the horizon. A study found that women on hormonal therapy who took elinzanetant had fewer hot flashes and slept better than women who didn’t take it.

Elinzanetant doesn’t contain the hormones estrogen or progesterone like hormone replacement therapy (HRT) does. This is important because HRT isn’t recommended for people with a history of breast cancer due to concerns that HRT can increase the risk of recurrence (the cancer coming back). HRT also may reduce the effectiveness of any medicines you’re taking to prevent recurrence. HRT also isn’t recommended for people with a high risk of developing the disease.

Elinzanetant is approved for use in the United Kingdom and Canada under the brand name Lynkuet, but hasn’t yet been approved by the U.S. Food and Drug Administration (FDA).

Like Veozah (chemical name: fezolinetant), elinzanetant reduces hot flashes by blocking molecules in the nervous system called neurokinins. When estrogen levels drop, neurokinins tell the cells in your brain’s temperature control center to work overtime. This can cause hot flashes and night sweats (hot flashes that happen while you’re sleeping). Doctors call these vasomotor symptoms.

Elinzanetant blocks two neurokinins — neurokinin-1 and neurokinin-3 — while Veozah only blocks neurokinin-3. This is why researchers think elinzanetant may be less likely to cause the liver problems linked to Veozah.

Veozah has been approved by the FDA for menopausal-related hot flashes since 2023 and is being studied in women with a history of breast cancer, but this research is ongoing.

The OASIS-4 study included 474 women. All but one of these women had been diagnosed with hormone receptor-positive breast cancer, most with stage I or stage II. About half were taking tamoxifen and half an aromatase inhibitor. All the women were having about 11 moderate-to-severe hot flashes a day.

Two-thirds of the women took elinzanetant once a day for a year. The other third took a placebo — a pill that looked just like elinzanetant but contained no medicine — once a day for 12 weeks and then took elinzanetant once a day for the next 40 weeks.

After the first four weeks, women taking elinzanetant had six fewer hot flashes per day and women taking the placebo had three fewer. After 12 weeks, women taking elinzanetant had eight fewer daily hot flashes and women taking the placebo had four fewer.

The most common mild or moderate side effects reported by the women — no matter which pill they were taking — were headache, fatigue, and drowsiness. Five women who were taking elinzanetant had elevated liver enzymes. The researchers determined all these incidents weren’t related to elinzanetant.

At the end of the study, the researchers offered women who took elinzanetant for a year the option to take the medicine for another two years. More than 90% did so.

“Although we did not collect data on treatment satisfaction in this trial, the observation that 91.6% of the participants who completed 52 weeks of treatment chose to continue receiving elinzanetant through an optional two-year extension suggests a high level of satisfaction,” the researchers wrote.