A Study to Confirm if Fezolinetant Helps Reduce Hot Flashes in Women With Breast Cancer Who Are Having Hormone Therapy

Registry record from ClinicalTrials.gov (NCT06440967). This is a study registration, not published results. Lead sponsor: Astellas Pharma Global Development, Inc.. Recruitment status: ACTIVE_NOT_RECRUITING. Phase: PHASE3. Study type: INTERVENTIONAL. Enrollment: 982 participants (ACTUAL). Conditions: Hot Flashes. Interventions: DRUG: Fezolinetant; DRUG: Placebo; DRUG: Tamoxifen; DRUG: Aromatase inhibitor. Primary outcome measures: Mean change from Baseline to Week 4 in the frequency of moderate to severe VMS , Baseline to Week 4; Mean change from Baseline to Week 12 in the frequency of moderate to severe VMS , Baseline to Week 12; Mean change from Baseline to Week 4 in the severity of moderate to severe VMS , Baseline to Week 4; Mean change from Baseline to Week 12 in the severity of moderate to severe VMS , Baseline to Week 12. Brief summary: One of the standard treatments for women with breast cancer is hormone therapy, but this treatment can cause hot flashes. Hormone replacement therapy, or HRT, is most often prescribed for hot flashes for women in menopause but cannot be given to women on hormone therapy for breast cancer. Fezolinetant, an alternative to HRT, treats hot flashes for women in menopause. As hot flashes happen in the same way for women on hormone therapy for breast cancer, fezolinetant could help these women. In this study, women on hormone therapy for breast cancer who have moderate to severe hot flashes will take part. They will either take fezolinetant or a placebo to treat their hot flashes. The placebo looks like fezolinetant but doesn't have any medicine in it. The main aim of this study is to confirm if women who take fezolinetant have fewer hot flashes that are less severe compared to women who take the placebo. Women 18 years or older seeking treatment for hot flashes. They can take part in the study if they have an average of 7 or more moderate to severe hot flashes each day. They are having hormone therapy for breast cancer from stage 0 (cancer cells that have not spread to nearby tissue) up to stage 3+ (the cancer has spread from the breast to the lymph nodes near the breast or the chest wall). The women will be assigned 1 of 2 study treatments (fezolinetant or placebo) by chance alone. Treatment will be double-blinded. That means that the women in the study and the study doctors will not know who takes which of the study treatments (fezolinetant or placebo). Women who take part in the study will take 1 tablet every day for 52 weeks (1 year). Each woman will be given an electronic handheld device with an app to track their hot flashes on a daily basis. Some women may be able to use the app on their own smartphone. They will also use another device to answer questions about how hot flashes affect their daily life. During the study, the women will visit their study clinic about every 4 weeks for a health check. The last clinic visit will be 3 weeks after the women take their last tablet of study treatment (fezolinetant or placebo). After this visit the women will be called twice to check their health. The women will be in the study for about 2 years.