Elinzanetant for Vasomotor Symptoms from Endocrine Therapy for Breast Cancer

Women receiving endocrine therapy for hormone receptor (HR)-positive breast cancer or its prevention among those at high risk for breast cancer commonly have vasomotor symptoms. Data are lacking on the effects of elinzanetant, a neurokinin-targeted therapy shown to be effective in treating vasomotor symptoms, in this population. We performed a phase 3 trial involving women 18 to 70 years of age with moderate-to-severe vasomotor symptoms associated with endocrine therapy for HR-positive breast cancer or its prevention. Women were randomly assigned in a 2:1 ratio to receive once-daily elinzanetant at a dose of 120 mg for 52 weeks or once-daily placebo for 12 weeks followed by once-daily elinzanetant at a dose of 120 mg for 40 weeks. The primary end points were the change in the mean daily frequency of moderate-to-severe vasomotor symptoms from baseline to week 4 and to week 12. A total of 316 participants were assigned to the elinzanetant group and 158 to the placebo-elinzanetant group. At baseline, the mean daily frequency of moderate-to-severe vasomotor symptoms was 11.4 episodes (95% confidence interval [CI], 10.7 to 12.2) in the elinzanetant group and 11.5 episodes (95% CI, 10.5 to 12.5) in the placebo-elinzanetant group. At week 4, the mean change from baseline in the mean daily frequency of moderate-to-severe vasomotor symptoms was -6.5 episodes (95% CI, -7.2 to -5.8) among those who were receiving elinzanetant and -3.0 episodes (95% CI, -3.9 to -2.2) among those who were receiving placebo (least-squares mean difference, -3.5 episodes; 95% CI, -4.4 to -2.6; P<0.001). At week 12, the mean change was -7.8 episodes (95% CI, -8.5 to -7.1) among those receiving elinzanetant and -4.2 episodes (95% CI, -5.2 to -3.2) among those receiving placebo (least-squares mean difference, -3.4 episodes; 95% CI, -4.2 to -2.5; P<0.001). During weeks 1 through 12, a total of 220 participants (69.8%) receiving elinzanetant and 98 (62.0%) receiving placebo reported at least one adverse event that occurred while receiving elinzanetant or placebo, with the most common being headache, fatigue, and somnolence. Serious adverse events occurred during weeks 1 through 12 in 8 participants (2.5%) receiving elinzanetant and 1 participant (0.6%) receiving placebo. Elinzanetant led to a significantly lower frequency of vasomotor symptoms associated with endocrine therapy than placebo. (Funded by Bayer; OASIS-4 ClinicalTrials.gov number, NCT05587296.).