Bayer’s Lynkuet Receives FDA Priority Review for Vasomotor Symptoms Associated With Breast Cancer Endocrine Therapy
Bayer announced that the U.S. Food and Drug Administration (FDA) has accepted the company’s supplemental New Drug Application (sNDA) for Lynkuet® (elinzanetant) and granted the application Priority Review. The regulatory submission seeks an expanded indication for Lynkuet to treat moderate to severe vasomotor symptoms (VMS), commonly known as hot flashes, in women receiving endocrine therapy for breast cancer.
The FDA’s acceptance and Priority Review designation represent an important regulatory milestone for Bayer as the company seeks to expand the potential use of Lynkuet beyond its currently approved indication. Lynkuet was approved by the FDA in October 2025 for the treatment of moderate to severe vasomotor symptoms associated with menopause. The medicine is a non-hormonal, dual neurokinin-targeted therapy that acts as an antagonist of both the neurokinin 1 (NK-1) and neurokinin 3 (NK-3) receptors.
The latest sNDA is supported by results from the Phase III OASIS-4 clinical trial, which evaluated elinzanetant in women experiencing moderate to severe vasomotor symptoms associated with endocrine therapy for hormone receptor-positive (HR+) breast cancer or its prevention.
FDA Priority Review Marks Regulatory Progress
Bayer said the FDA’s Priority Review designation reflects the importance of addressing vasomotor symptoms in women undergoing endocrine therapy for HR+ breast cancer. If approved for the proposed indication, Lynkuet could provide a non-hormonal treatment option specifically for this patient population.
“Currently, there are no FDA approved treatment options for moderate to severe vasomotor symptoms associated with endocrine therapy in patients with HR+ breast cancer in the U.S. This treatment gap underscores an important unmet medical need for this population,” said Kristie Baisden, DO, vice president, U.S. Medical Affairs, Women’s Health at Bayer.
Baisden added that the Priority Review represents a significant milestone for Bayer’s women’s health business and said the company looks forward to working with the FDA throughout the regulatory review process.
The potential indication is particularly relevant because endocrine therapy is an important component of treatment for many women with HR+ breast cancer. While these therapies can reduce the risk of cancer recurrence, treatment-associated symptoms can affect patients during what may be a prolonged course of therapy.
OASIS-4 Supports Supplemental Application
Bayer’s sNDA is based on findings from OASIS-4, a Phase III, 52-week, double-blind, randomized, placebo-controlled interventional study. The trial was conducted at 90 sites outside the United States and enrolled 474 women between 18 and 70 years of age who had moderate to severe vasomotor symptoms associated with endocrine therapy for HR+ breast cancer or breast cancer prevention.
Participants were randomized in a 2:1 ratio. A total of 316 women received elinzanetant for 52 weeks, while 158 women received placebo for the first 12 weeks before switching to elinzanetant for the remaining 40 weeks.
The study was designed to assess the effect of elinzanetant on the frequency of moderate to severe vasomotor symptoms. According to Bayer, Lynkuet met the study’s primary endpoints, demonstrating reductions in mean daily frequency of moderate to severe VMS from baseline to both Week 4 and Week 12 compared with placebo.
The findings provide the clinical evidence supporting Bayer’s regulatory submission for the proposed breast cancer-related indication.
The OASIS-4 results were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting and were simultaneously published in the New England Journal of Medicine in June 2025. The publication and presentation provided clinical data on the efficacy and safety profile of elinzanetant in women experiencing vasomotor symptoms associated with endocrine therapy.
Safety Findings From OASIS-4
Safety was also evaluated during the OASIS-4 trial. Bayer reported that commonly observed adverse events included headache, fatigue and somnolence.
During the first 12 weeks, when participants were in the placebo-controlled portion of the study, somnolence, fatigue and diarrhea occurred more frequently among participants receiving elinzanetant than among those receiving placebo.
The safety findings will form part of the FDA’s consideration of the supplemental application. As with any regulatory review, the FDA will evaluate the totality of clinical evidence, including the medicine’s benefits and potential risks, before reaching a decision on the proposed indication.
Lynkuet is already approved in the United States for moderate to severe vasomotor symptoms associated with menopause. The proposed new indication would extend its potential use to women whose symptoms occur in the context of endocrine therapy for HR+ breast cancer.
Vasomotor Symptoms and Breast Cancer Treatment
Hot flashes and other vasomotor symptoms can occur frequently during endocrine therapy. Endocrine treatment is commonly used in HR+ breast cancer because these cancers depend, at least in part, on hormone signaling for their growth.
In the United States, breast cancer accounts for approximately 30% of all cancers diagnosed in women, according to the information provided by Bayer. HR+ disease represents approximately 70% of breast cancer cases.
The duration of endocrine therapy can also be substantial. American Society of Clinical Oncology treatment recommendations include a minimum of five years of endocrine therapy for many patients, with treatment potentially extended to 10 years depending on cancer characteristics and individual clinical considerations.
Because endocrine therapy can continue for several years, treatment-related side effects such as hot flashes may persist over a significant period. For some patients, these symptoms can become an important consideration during ongoing cancer care.
Fatima Cardoso, MD, FESMO, director of the Breast Unit at Centre Antoine Lacassagne in Nice, France, and an OASIS-4 primary investigator, emphasized the importance of understanding vasomotor symptoms associated with endocrine therapy.
“Endocrine therapy is a standard of care for many women facing HR+ breast cancer and can commonly cause side effects such as vasomotor symptoms,” Cardoso said. She added that continued research into endocrine therapy-associated vasomotor symptoms is important as clinicians support women throughout their breast cancer treatment journey.
Lynkuet’s Mechanism of Action
Lynkuet, or elinzanetant, is a dual neurokinin receptor antagonist targeting NK-1 and NK-3 receptors. Unlike hormone replacement approaches, Lynkuet is not a hormone.
Neurokinin signaling has been investigated as a pathway involved in the regulation of thermoregulatory processes. By targeting neurokinin receptors, elinzanetant is designed to address the biological mechanisms associated with vasomotor symptoms.
The treatment is therefore being developed as a non-hormonal approach to reducing moderate to severe hot flashes. This characteristic is particularly relevant in the breast cancer setting, where treatment decisions involving hormones can require consideration of the underlying hormone receptor status and cancer treatment strategy.
The FDA’s review of the supplemental application will determine whether the existing evidence supports use of Lynkuet in women experiencing vasomotor symptoms associated with endocrine therapy for HR+ breast cancer.
Previous FDA Approval in Menopause
The proposed breast cancer indication builds on Lynkuet’s existing regulatory status in the United States. The FDA approved Lynkuet in October 2025 for the treatment of moderate to severe vasomotor symptoms due to menopause.
That approval was supported by results from three Phase III studies: OASIS-1, OASIS-2 and OASIS-3. Together, the studies evaluated the efficacy and safety of elinzanetant in women experiencing moderate to severe menopausal hot flashes.
The OASIS clinical development program has therefore provided Bayer with a broader body of evidence concerning elinzanetant and vasomotor symptoms. OASIS-4 extended the investigation into a different clinical population—women receiving endocrine therapy for HR+ breast cancer or breast cancer prevention.
The current regulatory submission represents Bayer’s effort to translate those clinical findings into a potential additional indication.
Important Safety Information
Lynkuet is a prescription medicine currently indicated in the United States to reduce moderate to severe hot flashes associated with menopause. It is not a hormone.
According to the safety information provided by Bayer, Lynkuet should not be taken during pregnancy. Women who can become pregnant should discuss pregnancy testing with their healthcare provider before starting treatment and use effective contraception during treatment and for two weeks after stopping the medicine.
Patients should inform their healthcare providers about existing medical conditions, including liver problems and a history of seizures or conditions that could increase seizure risk. Patients should also disclose all prescription and over-the-counter medicines, vitamins and herbal supplements because Lynkuet may affect the way other medicines work, and other medicines may affect Lynkuet.
Patients taking Lynkuet are advised to avoid grapefruit and grapefruit juice during treatment.
The medicine can cause central nervous system effects, including somnolence, fatigue, dizziness, vertigo and presyncope. Patients experiencing drowsiness or other relevant effects should avoid driving or hazardous activities until the symptoms resolve.
Lynkuet may also increase liver enzyme levels. Bayer’s safety information states that healthcare providers should perform liver blood tests before treatment and three months after starting treatment. Patients should promptly contact their healthcare provider if they experience symptoms potentially associated with liver problems, including unusual tiredness, reduced appetite, nausea, vomiting, itching, jaundice, pale stools, dark urine or abdominal pain.
The safety information also warns of pregnancy loss and seizure risk. Patients who experience loss of consciousness or a seizure should seek immediate medical attention.
Commonly reported side effects include headache, fatigue, dizziness, drowsiness or sleepiness, abdominal pain, rash, diarrhea and muscle spasms.
Potential Expansion of Women’s Health Portfolio
The supplemental application reinforces Bayer’s focus on women’s health and its efforts to develop treatment options for conditions affecting women at different stages of life.
For women with HR+ breast cancer, the proposed indication would address symptoms that may arise as a consequence of an established cancer treatment. The potential role of Lynkuet would therefore be supportive of symptom management rather than a treatment intended to directly target the underlying cancer.
The FDA’s Priority Review now moves the application into the regulatory evaluation process. Bayer said it will continue working with the agency as the review progresses.
The OASIS-4 data provide the foundation for the application, with the Phase III study demonstrating that elinzanetant reduced the frequency of moderate to severe vasomotor symptoms at the key four- and 12-week assessment points compared with placebo.
As the FDA reviews the sNDA, the outcome will determine whether Lynkuet can be used for this additional patient population in the United States. For Bayer, the application represents the next regulatory step in expanding the clinical application of a dual NK-1/NK-3 receptor antagonist and further developing its portfolio of non-hormonal therapies for women’s health.
The company’s continued development of Lynkuet also highlights the broader effort to address treatment-related symptoms that can accompany long-term cancer therapy. With endocrine therapy often continuing for multiple years, managing vasomotor symptoms remains an important component of comprehensive care for women with HR+ breast cancer.
About Lynkuet® (elinzanetant)
Lynkuet® (elinzanetant) 60mg capsules is an FDA-approved, hormone-free prescription treatment for moderate to severe hot flashes due to menopause. Lynkuet is the first and only dual neurokinin (NK) targeted therapy, neurokinin 1 (NK1) and neurokinin 3 (NK3) receptor antagonist approved for the treatment of moderate to severe hot flashes due to menopause.
About the OASIS-1, 2 and 3 trials
The FDA approval of Lynkuet® (elinzanetant) 60mg capsules is supported by data from three Phase III clinical trials that evaluated the safety and efficacy of Lynkuet for the treatment of moderate to severe hot flashes due to menopause. The efficacy of Lynkuet for the treatment of moderate to severe hot flashes due to menopause was demonstrated in the first 12 weeks of two randomized, double-blind, placebo-controlled, multicenter clinical trials, OASIS-1 and OASIS-2, in 796 menopausal women.
The co-primary efficacy endpoints in both trials were the mean change in frequency and severity of moderate to severe hot flashes from baseline to weeks 4 and 12, including day and night hot flashes. The safety of Lynkuet was evaluated in three randomized, double-blind, placebo-controlled, multicenter clinical trials (OASIS-1, OASIS-2 and OASIS-3) in 1,420 women. In OASIS-3, 627 women received Lynkuet or placebo for up to 52 weeks to evaluate long-term safety.
About Bayer
Bayer is a global enterprise with core competencies in the life science fields of health care and nutrition. In line with its mission, “Health for all, Hunger for none,” the company’s products and services are designed to help people and the planet thrive by supporting efforts to master the major challenges presented by a growing and aging global population.
Bayer is committed to driving sustainable development and generating a positive impact with its businesses. At the same time, the Group aims to increase its earning power and create value through innovation and growth. The Bayer brand stands for trust, reliability and quality throughout the world. In fiscal 2025, the Group employed around 88,000 people and had sales of 45.6 billion euros. R&D expenses amounted to 5.8 billion euros.