Hot Flashes From Breast Cancer Treatment May Soon Have an FDA-Approved Fix

If you take tamoxifen, letrozole, anastrozole or exemestane to lower your risk of breast cancer coming back, you may know the drill: a wave of heat, a flushed face, soaked sheets at 3 a.m. For many women, hot flashes are not a minor annoyance. They are one of the most common reasons people cut back on, or stop, the endocrine therapy that protects them.

That could change. On Sept. 28, 2026, Bayer announced that the FDA has accepted its application and granted priority review to elinzanetant (Lynkuet) for moderate to severe hot flashes caused by endocrine therapy for hormone receptor (HR)-positive breast cancer. If approved, it would be the first FDA-approved treatment specifically for this problem.

Important: this is not an approval yet. The drug is already on the market for menopause-related hot flashes, but it has not been approved for hot flashes caused by breast cancer treatment. Priority review means the FDA has agreed to decide on that new use faster than usual.

What is elinzanetant?

Elinzanetant is a once-daily pill that is not a hormone. It blocks two chemical signals (called neurokinin-1 and neurokinin-3) in the part of the brain that controls body temperature. When estrogen drops, whether from menopause or from breast cancer treatment, that temperature center can misfire and trigger hot flashes.

Because most women with HR-positive breast cancer are advised to avoid hormone therapy, a nonhormonal option matters. The FDA already approved elinzanetant (Lynkuet) in October 2025 for hot flashes caused by natural menopause. The new application asks to extend its use to women whose symptoms are caused by breast cancer treatment.

What the trial found

The application is based on OASIS-4, a phase 3 trial of 474 women aged 18 to 70 who were taking tamoxifen or an aromatase inhibitor and having at least 35 moderate to severe hot flashes per week. About two-thirds received elinzanetant and one-third received a placebo for 12 weeks. After that, everyone could take elinzanetant for up to a year.

• Before treatment, women averaged about 11 moderate to severe hot flashes per day.
• By week 4, women on elinzanetant had about 6.5 fewer hot flashes per day, compared with about 3 fewer on placebo.
• By week 12, the drop was about 7.8 per day with elinzanetant vs 4.2 with placebo.

Improvement started as early as the first week, and women also reported better sleep and quality of life.

In plain terms: the placebo effect for hot flashes is large (it is in nearly every hot-flash study), but elinzanetant roughly doubled the benefit.

Side effects to know about

During the first 12 weeks, the most common side effects with elinzanetant were sleepiness (about 11%), headache and fatigue (each about 10%), joint pain (about 6%) and nausea (about 6%). Serious side effects were uncommon, occurring in 2.5% of women on the drug and 0.6% on placebo. Over a full year, researchers reported that the drug remained well tolerated, and a two-year extension study is still collecting safety data.

Already approved for this use outside the U.S.

The U.S. is catching up. Elinzanetant is already authorized in the European Union for hot flashes caused by adjuvant endocrine therapy for breast cancer, and Health Canada approved it for breast cancer patients in August 2026.

Other findings from OASIS-4 may also help patients:

• It worked with either type of endocrine therapy. A 2026 analysis found lasting relief whether women took tamoxifen or an aromatase inhibitor.
• Most women chose to keep taking it. At the end of the one-year trial, 91.6% of participants chose to continue for another two years.
• Liver checks are part of the plan. For its current menopause approval, the FDA recommends liver blood tests before starting elinzanetant and again at three months.

What you can do now

If hot flashes are making it hard to stay on your endocrine therapy, don't stop your medication on your own. Tell your oncologist. There are already options worth discussing, including certain antidepressants, gabapentin and nonmedication approaches such as cognitive behavioral therapy. Your team can help you weigh them while the FDA reviews elinzanetant.

Questions to ask your care team

• Are my hot flashes severe enough that they might affect whether I stay on my endocrine therapy?
• Which nonhormonal options are safe with the specific drug I take?
• If elinzanetant is approved for breast cancer patients, would I be a candidate?
• Could any hot-flash treatment interact with tamoxifen or my other medications?

References

1. Bayer. "U.S. FDA Accepts sNDA and Grants Priority Review to Bayer's Lynkuet (Elinzanetant) for a New Indication for the Treatment of Moderate to Severe Vasomotor Symptoms Due to Endocrine Therapy Related to Breast Cancer." Business Wire, Sept. 28, 2026.
2. OncLive Staff. "FDA Grants Priority Review to Elinzanetant for Endocrine Therapy-Associated Vasomotor Symptoms in HR+ Breast Cancer." OncLive, Sept. 28, 2026.
3. Cardoso, Fatima, et al. "Efficacy and Safety of Elinzanetant for Vasomotor Symptoms Associated With Endocrine Therapy: Phase 3 OASIS-4 Trial." Journal of Clinical Oncology, 2025.
4. European Medicines Agency. "Lynkuet: European Public Assessment Report." European Medicines Agency.
5. The Globe and Mail. "Health Canada Approves Drug to Treat Hot Flashes and Night Sweats in Breast Cancer Patients." August 2026.
6. The ASCO Post. "Elinzanetant May Reduce Side Effects of Endocrine Therapy Among Patients With Breast Cancer." March 2026.
7. Rheumatology Advisor. "Lynkuet (Elinzanetant) for the Treatment of Vasomotor Symptoms Due to Menopause." November 2025.

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