FDA Grants Priority Review to Elinzanetant for VMS in HR+ Breast Cancer Patients on Endocrine Therapy

The US Food and Drug Administration (FDA) has accepted a supplemental New Drug Application (sNDA) and granted Priority Review designation to Bayer's elinzanetant (Lynkuet®) for the treatment of moderate-to-severe vasomotor symptoms (VMS) in women receiving endocrine therapy for hormone receptor–positive (HR+) breast cancer, according to a press release from Bayer.

The FDA's action identifies the application as addressing an unmet medical need, as no approved pharmacologic options currently exist for this indication in the US.

"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," Kristie Baisden, DO, Vice President, US Medical Affairs, Women's Health at Bayer, said in a press release.

Trial Overview: OASIS-4. The sNDA submission is supported by data from the phase 3 OASIS-4 clinical trial, a 52-week, double-blind, randomized, placebo-controlled study conducted across 90 sites outside the United States.¹ A total of 474 women aged 18 to 70 years with moderate to severe VMS associated with endocrine therapy for HR+ breast cancer or its prevention were enrolled. Participants were randomized 2:1 to receive elinzanetant for 52 weeks (n=316) or placebo for 12 weeks followed by elinzanetant for 40 weeks (n=158).¹

The trial met its co-primary endpoints, demonstrating statistically significant reductions in mean daily frequency of moderate to severe VMS from baseline at weeks 4 and 12 compared with placebo.¹ During the 12-week placebo-controlled period, somnolence, fatigue, and diarrhea were reported more frequently with elinzanetant than with placebo; overall common adverse events included headache, fatigue, and somnolence.¹ Key findings were presented at the American Society of Clinical Oncology (ASCO) 2025 Annual Meeting and simultaneously published in the New England Journal of Medicine.¹

Clinical Context and Disease Burden. Breast cancer accounts for approximately 30% of all cancers diagnosed in women in the United States, with HR+ subtypes comprising roughly 70% of all breast cancer cases.³ Current ASCO guidelines recommend endocrine therapy as standard adjuvant treatment for HR+ breast cancer, with a minimum recommended duration of 5 years and potential extension to 10 years depending on disease characteristics and individual risk factors.⁴ Hot flashes are among the most commonly reported adverse effects of endocrine therapy and represent a leading cause of early treatment discontinuation—a clinically significant concern given the survival benefit associated with completing the full treatment course.

OASIS-4 primary investigator Fatima Cardoso, MD, FESMO, Director of the Breast Unit at Centre Antoine Lacassagne, noted that "endocrine therapy is a standard of care for many women facing HR+ breast cancer and can commonly cause side effects such as vasomotor symptoms," underscoring the importance of expanding the evidence base for symptom management in this population.

Drug and Drug-Class Background. Elinzanetant is a non-hormonal, dual neurokinin receptor antagonist targeting both the NK-1 and NK-3 receptors, which are implicated in thermoregulatory signaling pathways in the hypothalamus. The FDA first approved elinzanetant in October 2025 for moderate to severe VMS due to menopause, based on data from three Phase III trials—OASIS-1, OASIS-2, and OASIS-3—conducted in 1,420 women.²·⁵·⁶ OASIS-1 and OASIS-2 established efficacy on co-primary endpoints of VMS frequency and severity at weeks 4 and 12 in menopausal women, while OASIS-3 evaluated long-term safety over 52 weeks.⁵·⁶

Interpretive Framing and Limitations. The Priority Review designation signals the FDA's assessment of potential clinical benefit, but it does not guarantee approval, and the totality of the benefit-risk profile will be evaluated through the full review process. The OASIS-4 trial was conducted entirely outside the United States, which may raise questions about generalizability to US patient populations. The placebo-controlled period was limited to 12 weeks, and long-term comparative safety data against active comparators—such as selective serotonin reuptake inhibitors or serotonin-norepinephrine reuptake inhibitors, which are commonly used off-label for VMS in this setting—were not reported. Whether symptom reduction in OASIS-4 translates to improved endocrine therapy adherence or downstream survival outcomes remains to be established.

References

1. Cardoso F, Parke S, Brennan DJ, et al. Elinzanetant for vasomotor symptoms from endocrine therapy for breast cancer. N Engl J Med. 2025;393:753-763.
2. LYNKUET® (elinzanetant) [Prescribing Information]. Whippany, NJ: Bayer HealthCare Pharmaceuticals, Inc.; August 2026.
3. Huang H, Wei T, Zhang A, et al. Trends in the incidence and survival of women with hormone receptor-positive breast cancer from 1990 to 2019: a large population-based analysis. Sci Rep. 2024;14(1):23690. doi:10.1038/s41598-024-74746-1
4. Burstein HJ, Temin S, Anderson H, et al. Adjuvant endocrine therapy for women with hormone receptor-positive breast cancer: American Society of Clinical Oncology clinical practice guideline focused update. J Clin Oncol. 2014;32(21):2255-2269. doi:10.1200/JCO.2013.54.2258