4 Findings About Elinzanetant During Breast Cancer Endocrine Therapy

The trial studied a defined endocrine therapy population

OASIS-4 enrolled women aged 18 to 70 taking tamoxifen or an aromatase inhibitor, with or without ovarian-suppression medicine, for hormone-receptor-positive breast cancer or its prevention. Eligibility required at least 35 moderate-to-severe hot flashes in a recorded week.¹

The trial excluded metastatic breast cancer at diagnosis and recurrence during adjuvant endocrine therapy. Its findings should not be extended automatically to those situations.¹

The benefit was measured against substantial placebo improvement

The manufacturer funded the trial, which randomized 474 women, with 316 assigned elinzanetant and 158 placebo initially. Baseline hot-flash frequency averaged about 11.4 to 11.5 episodes daily.²

The adjusted difference favored elinzanetant by 3.5 moderate-to-severe episodes per day at week four and 3.4 at week twelve. At week twelve, both groups had improved: mean reductions were 7.8 episodes with elinzanetant and 4.2 with placebo. The adjusted 3.4 figure is the modeled treatment difference, rather than simple subtraction of those two means.²

The placebo group switched treatment at week twelve

Participants assigned elinzanetant received 120 mg daily for 52 weeks. The comparison group received placebo for 12 weeks, then elinzanetant for 40 weeks.¹

Consequently, observations later in the year do not provide a continuing comparison with a group remaining on placebo. The four- and twelve-week comparisons answer the primary efficacy question; a year of reported treatment is a different observation window.¹

Adverse events and monitoring remain part of the decision

During the first twelve weeks, 69.8% on elinzanetant and 62.0% on placebo reported an adverse event. Serious events occurred in 2.5% and 0.6%, respectively. These reports do not mean every event was caused by the assigned medicine.²

The current U.S. label calls for liver tests before treatment and at three months, warns about seizures, and contraindicates use in pregnancy. People experiencing sleepiness or other nervous-system effects should avoid driving until those effects resolve. An oncology pharmacist should check the full medicine list.³

Check the indication where you live

As checked October 16, 2026, the U.S. label lists hot flashes due to menopause.³ Bayer’s⁴ September 2026 announcement described priority review of an application for hot flashes associated with breast cancer endocrine therapy. That announcement is not an approval for the additional indication.⁴

Bring a record of daytime episodes, night waking and current medicines to the oncology appointment. Ask whether this study fits your circumstances and which options are available locally. Our elinzanetant prescribing guide covers label precautions in more detail.

The “Visit Brief” in My Body Changed. Now What? helps organize symptom impact, health history, treatments already tried and questions about hormonal and nonhormonal options.