A Study to Find Out if Fezolinetant Helps Reduce Moderate to Severe Hot Flashes in Women in Asia Going Through Menopause

This study will consist of a screening period and a 24-week treatment period. Safety follow up will occur 3 weeks after the last dose of study drug.

Inclusion criteria

• Participant has a body mass index ≥16 kg/m^2 and ≤38 kg/m^2 (extremes included) at screening visit.
• Participant must be seeking treatment or relief for vasomotor symptoms (VMS) associated with menopause and confirmed as menopausal per 1 of the following criteria at the screening visit:

• Spontaneous amenorrhea for ≥ 12 consecutive months
• Spontaneous amenorrhea for ≥ 6 months with biochemical criteria of menopause (follicle stimulating hormone [FSH] > 40 IU/L); or
• Having had bilateral oophorectomy ≥ 6 weeks prior to the screening visit (with or without hysterectomy)
• FSH > 40 IU/L if participants received hysterectomy but still have ovary
• Within the 10 days prior to randomization, participant must have a minimum average of 7 to 8 moderate to severe HFs (VMS) per day, or 50 to 60 per week.
• Participant is in good general health as determined on the basis of medical history and general physical examination, including a bimanual clinical pelvic examination and clinical breast examination devoid of relevant clinical findings, performed at the screening visit; hematology and biochemistry parameters, pulse rate and/or blood pressure, and electrocardiogram (ECG) within the reference range for the population studied, or showing no clinically relevant deviations.
• Participant has documentation of a normal/negative or no clinically significant findings mammogram (or echo) (e.g. < BI-RADS class 4; obtained at screening or within the prior 12 months of study enrollment). Appropriate documentation includes a written report or an electronic report indicating normal/negative or no clinically significant mammographic findings.
• Participant is willing to undergo a transvaginal ultrasound (TVU) to evaluate the uterus and ovaries at screening and week 24 (end-of-treatment), and for participants who are withdrawn from the study prior to completion, a TVU at the early discontinuation (ED) visit. This is not required for participants who have had a partial (supra-cervical) or full hysterectomy.
• Participant is willing to undergo an endometrial biopsy at screening, and at week 24 (end of treatment) or early discontinuation (ED) visit if endometrial thickness >4mm indicated by TVU; and participant is willing to undergo an endometrial biopsy at any time during the study in the case of uterine bleeding. This is not required for participants who have had a partial (supracervical) or full hysterectomy. A biopsy with insufficient material for evaluation, or unevaluable material, is acceptable provided the endometrial thickness is no greater than 8 mm.
• Participant has documentation of a normal or not clinically significant Pap test (or equivalent cervical cytology within the previous 12 months of study enrollment or at screening. This is not required for participants who have had a full hysterectomy.
• Participant has a negative urine pregnancy test at screening, this is not required for participants who have had a full hysterectomy.
• Participant has negative serology panel [i.e., negative hepatitis B surface antigen (HBsAg) and negative hepatitis C virus antibody (HCVAb) screens] at screening.
• Participant agrees not to participate in another interventional study while participating in the present study.

Exclusion criteria

• Participant uses a prohibited therapy (strong and moderate cytochrome P450 1A2 [CYP1A2] inhibitors, hormone replacement therapy [HRT], hormonal contraceptive or any treatment for VMS [prescription, over the counter, or herbal]) or is not willing to wash out and discontinue use of such drugs for the full duration of study conduct.
• Participant has known substance abuse or alcohol addiction within 6 months of screening.
• Participant has a history of a malignant tumor, except for non-metastatic basal cell carcinoma of the skin.
• Participant has uncontrolled hypertension, defined as systolic blood pressure ≥ 140 mmHg or diastolic blood pressure as ≥ 90 mmHg based on an average of 2 to 3 readings within the screening period. Participants with a medical history of hypertension who are well controlled may be enrolled. Participants who do not meet these criteria may, at the discretion of the investigator, be re-assessed after initiation or review of antihypertensive measures.
• Participant has a history of severe allergy, hypersensitivity, or intolerance to drugs in general, including the study drug and any of its excipients.
• For Participants with a uterus: Participant has an unacceptable result from the TVU assessment at screening, i.e. full length of endometrial cavity cannot be visualized or presence of a clinically significant finding.
• For Participants with a uterus and endometrial thickness >4mm indicated by TVU: Participant has an endometrial biopsy confirming presence of disordered proliferative endometrium, endometrial hyperplasia, endometrial cancer, or other clinically significant at screening. A biopsy with insufficient material for evaluation, or unevaluable material is acceptable provided the endometrial thickness is no greater than 8 mm.
• Participant has a history within the last 6 months of undiagnosed uterine bleeding.
• Participant has a history of seizures or other convulsive disorders.
• 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) or malignancy that could confound interpretation of the study outcome.
• Participant has active liver disease, jaundice, elevated liver aminotransferases (alanine aminotransferase [ALT] or aspartate aminotransferase [AST]), elevated total or direct bilirubin, elevated INR or elevated alkaline phosphatase (ALP). Patients with mildly elevated ALT or AST up to < 1.5 × the upper limit of normal (ULN) can be enrolled if total and direct bilirubin are normal. Patients 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. Patients with Gilbert's syndrome with elevated total bilirubin may be enrolled as long as hemolysis is ruled out (i.e. direct bilirubin, hemoglobin and reticulocytes are normal).
• Participant has creatinine > 1.5 × ULN; or estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease formula ≤ 59 mL/min/1.73 m^2 at screening.
• Participant has a positive result for human immunodeficiency virus (HIV) at screening.
• Participant has a history of suicide attempt or suicidal behavior within the last 12 months or has suicidal ideation within the last 12 months (a response of "yes" to question 4 or 5 on the suicidal ideation portion of the Columbia-Suicide Severity Rating Scale [C-SSRS]), or who is at significant risk to commit suicide at screening and at visit 2.
• Participant has previously been enrolled in a clinical trial with fezolinetant.
• Participant has received investigational study drug within 28 days or 5 half-lives, whichever is longer, prior to screening.
• Participant is unable or unwilling to complete the study procedures.
• Participant has any condition which makes the subject unsuitable for study participation.