A Study to Confirm if Fezolinetant Helps Reduce Hot Flashes in Japanese Women Going Through Menopause

Exclusion Criteria

• •Participant has a history of an undiagnosed uterine bleeding within the 6 months prior to the screening visit (visit 1).
• •Participant has a current malignant tumor or history (except for a participant who has not received treatment for malignant tumors for at least 5 years before informed consent acquisition and was not considered to have recurrence) of a malignant tumor except for non-metastatic basal cell carcinoma of the skin.
• •Participant has a medical condition or chronic disease (including history of neurological \[including cognitive\], hepatic, renal, cardiovascular, gastrointestinal, pulmonary \[e.g., moderate asthma\], endocrine, or gynecological disease) that could confound interpretation of the study outcome.
• •Participant uses a prohibited therapy (hormone therapy, hormone replacement therapy (HRT), hormonal contraceptive, any treatment for menopausal symptoms \[prescription medications, over-the-counter, or herbal/Kampo medicines\] or strong or moderate cytochrome P450 1A2 (CYP1A2) inhibitors) and is not willing to wash out or discontinue use of such drugs from screening visit (visit 1) through the follow-up visit (visit 6) or it is not medically appropriate to discontinue such drugs for the duration of the study.
• •Participant has been randomized/registered in a clinical study with fezolinetant previously or had previous exposure to marketed fezolinetant elsewhere.
• •Participant has a present or previous history of participation in this study.
• •Participant has received any investigational therapy within 28 days or 5 half-lives, whichever is longer, prior to screening (visit 1).
• •Participant has an unacceptable result from the transvaginal ultrasound (TVU) assessment at screening (i.e., full length of endometrial cavity cannot be visualized or presence of clinically significant abnormal findings).
• •Participant has documentation of a clinically significant abnormal Papanicolaou (Pap) test (or equivalent cervical cytology) within the 12 months prior to the screening visit (visit 1) or at screening.
• •Participant has active liver disease, jaundice, or elevated liver aminotransferases (alanine aminotransferase (ALT) or aspartate aminotransferase (AST)), elevated total bilirubin (TBL) or direct bilirubin (DBL), elevated international normalized ratio (INR), or elevated alkaline phosphatase (ALP) at screening. A participant with mildly elevated ALT or AST up to \< 1.5 × upper limit of normal (ULN) can be enrolled if TBL and DBL are normal. Participant with mildly elevated ALP (up to \< 1.5 × ULN) can be enrolled if cholestatic liver disease is excluded and no cause other than fatty liver is diagnosed. Participant with Gilbert's syndrome with elevated TBL may be enrolled as long as DBL, hemoglobin and reticulocytes are normal.
• •Participant has creatinine \> 1.5 × ULN or estimated glomerular filtration rate using the Modification of Diet in Renal Disease formula \</=30 mL/min/1.73 m\^2 at screening.
• •Participant has positive hepatitis serology panel (i.e., positive hepatitis B surface (HBs) antigen and/or positive hepatitis C virus (HCV) antibody) at screening. If HCV antibody test result is equivocal, hepatitis C virus ribonucleic acid (HCV RNA) test at study site is allowed. Participant can be enrolled if that result is normal or not abnormal.
• •Participant is not in good general health as determined on the basis of medical history and general physical examination performed at the screening; hematology parameters, biochemistry parameters, pulse rate, blood pressure, electrocardiogram (ECG) outside the reference range for the population studied, or is showing clinically relevant deviations.
• •Participant has a history of suicide attempt or suicidal behavior within the 12 months prior to study enrollment or suicidal ideation within the 12 months prior to study enrollment (a response of "yes" to question 4 or 5 on the suicidal ideation portion of the Columbia Suicide Severity Rating Scale (C-SSRS)), or is at significant risk to commit suicide at day 1 (visit 2).
• •Participant is unable or unwilling to complete the study procedures.
• •Participant has any condition which makes the participant unsuitable for study participation.
• •Participant has a known or suspected hypersensitivity to fezolinetant or any components of the formulation used.
• •Participant is the investigator or a member of the study site staff.
• •Participant is an employee of Astellas, the study-related contract research organizations (CROs) or site management organization.