Bayer announced that the US Food and Drug Administration (FDA) has accepted a supplemental New Drug Application (sNDA) and granted Priority Review designation for elinzanetant (Lynkuet) for a new indication: the treatment of moderate to severe vasomotor symptoms (VMS) in women receiving endocrine therapy for the treatment or prevention of hormone receptor–positive (HR+) breast cancer. The submission is supported by data from the Phase III OASIS-4 trial.
Elinzanetant, a dual neurokinin-1 and neurokinin-3 (NK-1/NK-3) receptor antagonist, was first approved by the FDA in October 2025 for moderate to severe hot flashes due to menopause. The Priority Review designation reflects the absence of any currently FDA-approved treatment for endocrine therapy–related VMS in this patient population, though a PDUFA action date was not disclosed in the announcement.
Key finding
In the Phase III OASIS-4 trial, elinzanetant met both co-primary endpoints by significantly reducing the mean daily frequency of moderate to severe VMS at weeks 4 and 12 compared with placebo in women on endocrine therapy for HR+ breast cancer, though specific numerical results were not disclosed in the regulatory announcement.
Study Design
| Trial | OASIS-4: a 52-week, double-blind, randomized, placebo-controlled Phase III study conducted at 90 sites outside the US |
|---|---|
| Population | 474 women aged 18–70 with moderate to severe VMS associated with endocrine therapy for HR+ breast cancer or its prevention |
| Treatment | Elinzanetant (n=316) for 52 weeks vs. placebo for 12 weeks followed by elinzanetant for 40 weeks (n=158); 2:1 randomization |
| Primary endpoint | Mean change from baseline in daily frequency of moderate to severe VMS at weeks 4 and 12 vs. placebo |
Key findings from OASIS-4 were presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in June 2025 and simultaneously published in the New England Journal of Medicine. The trial was conducted exclusively at international sites; the sNDA submission is under FDA review for a US indication.
Results and Safety
Elinzanetant met both co-primary endpoints in OASIS-4, demonstrating a statistically significant reduction in the mean daily frequency of moderate to severe VMS at weeks 4 and 12 compared with placebo. Specific numerical effect sizes and p-values were not disclosed in the regulatory announcement; the full dataset is available in the NEJM publication.
Overall, the most commonly reported adverse events during the 52-week trial were headache, fatigue, and somnolence. During the placebo-controlled period (the first 12 weeks), somnolence, fatigue, and diarrhea occurred more frequently in the elinzanetant arm than in the placebo arm. No new safety signals beyond those observed in the menopausal VMS trials were described in the announcement.
Clinical Context
Breast cancer accounts for approximately 30% of all cancers in US women, with HR+ subtypes representing roughly 70% of all breast cancer cases. Endocrine therapy, recommended by American Society of Clinical Oncology guidelines for a minimum of five years and potentially up to 10 years, is a cornerstone of HR+ breast cancer management, but hot flashes are a well-recognized and frequently reported side effect that can affect treatment adherence and quality of life. As of the time of this announcement, no FDA-approved pharmacologic option exists specifically for endocrine therapy–associated VMS in this population.
The Priority Review designation, which sets a six-month FDA review clock rather than the standard 10 months, underscores the agency’s recognition of this unmet need. If approved, elinzanetant would represent the first FDA-sanctioned treatment for this indication. Whether the label would extend to patients receiving endocrine therapy for breast cancer prevention, a subgroup included in OASIS-4, will depend on the outcome of the FDA’s review.
Sources
- 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.” Press release. September 25, 2026. View source.
AI disclosure: This article was prepared with assistance from generative AI using the source material cited above. It was reviewed and edited by Brandon Twyford before publication.
