A Study to Assess the Effect of Food With Fezolinetant in Healthy Female Participants

The purpose of this study is to evaluate the effect of food on the pharmacokinetics of a single oral dose of fezolinetant under fasted and fed conditions in healthy female participants. The study will also evaluate the safety and tolerability of a single oral dose of fezolinetant under fasted and fed conditions in healthy female participants.

Each participant will participate in 2 treatment periods separated by a washout of at least 5 days between investigational product (IP) administration in each period. Participants will be admitted to the clinical unit on day -1 of period 1 and will be in clinical unit for periods 1 and 2. On day 1 of each period, participants will receive fezolinetant followed by a 72-hour blood sampling period. The study will be completed with an end-of-study visit (ESV) which will take place 5 to 9 days after the 72-hour blood sampling period in period 2 or at the time of early discontinuation from the study.

Eligibility Criteria:
Inclusion Criteria:

* Participant has a body mass index (BMI) range of 18.5 to 34.0 kg/m\^2, inclusive and weighs at least 50 kg at screening.
* Female participant is not pregnant and at least 1 of the following conditions apply:

  * Not a woman of childbearing potential (WOCBP)
  * WOCBP who agrees to follow the contraceptive guidance for at least 30 days prior to day -1 of period 1 through at least 30 days after final IP administration
* Female participant must agree not to breastfeed starting at screening and throughout the study period and for 30 days after final IP administration.
* Female participant must not donate ova starting at first dose of IP and throughout the study period and for 30 days after final IP administration.
* Participant agrees not to participate in another interventional study while participating in the present study.

Exclusion Criteria:

* Participant has received any investigational therapy within 28 days or 5 half-lives, whichever is longer, prior to screening.
* Participant has any condition which makes the participant unsuitable for study participation.
* Female participant who has been pregnant within 6 months prior to screening or breastfeeding within 3 months prior to screening.
* Participant has a known or suspected hypersensitivity to fezolinetant or any components of the formulation used.
* Participant has had previous exposure with fezolinetant.
* Participant has any of the liver function tests (alkaline phosphatase \[ALP\], alanine aminotransferase \[ALT\], aspartate aminotransferase \[AST\] and total bilirubin \[TBL\]) \> 1.5 × the upper limit of normal (ULN) on day -1 of period 1. In such a case, the assessment may be repeated once.
* Participant has creatinine level outside normal limits on day -1 of period 1. In such a case, the assessment may be repeated once.
* Participant has any clinically significant history of allergic conditions (including drug allergies, asthma, eczema or anaphylactic reactions, but excluding untreated, asymptomatic, seasonal allergies) prior to first IP administration.
* Participant has any history or evidence of any clinically significant cardiovascular, gastrointestinal, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, renal and/or other major disease or malignancy.
* Participant has/had febrile illness or symptomatic, viral, bacterial (including upper respiratory infection) or fungal (noncutaneous) infection within 1 week prior to day -1 of period 1.
* Participant has any clinically significant abnormality following the physical examination, ECG and protocol-defined clinical laboratory tests at screening or on day -1 of period 1.
* Participant has a mean pulse of \< 45 or \> 90 bpm or systolic blood pressure ≥ 130 millimeters of mercury (mmHg) or diastolic blood pressure ≥ 80 mmHg based on the average of 3 readings. These 3 readings must occur on at least 2 different occasions during the screening period or on day -1 of period 1. Repeat measurements will not be taken during screening, but may be taken on day -1 of period 1.
* Participant has a mean corrected QT interval using Fridericia's formula (QTcF) of \> 470 msec on day -1 of period 1. If the mean QTcF exceeds the limits above, 1 additional triplicate ECG may be taken.
* Participant has used any prescribed or nonprescribed drugs (including vitamins, oral contraceptives or hormone replacement therapy \[HRT\] and natural and herbal remedies, e.g., St. John's Wort) in the 2 weeks prior to first IP administration except for occasional use of acetaminophen (up to 2 g/day) and topical dermatological products (including corticosteroid products).
* Participant has smoked, used tobacco-containing products and nicotine or nicotine-containing products (e.g., electronic vapes) within 6 months prior to screening or the participant tests positive for cotinine at screening or on day -1 of period 1.
* Participant has a history of consuming \> 7 units of alcoholic beverages per week within 6 months prior to screening or has a history of alcoholism or drug/chemical/substance abuse within 2 years prior to screening (note: 1 unit = 12 ounces of beer, 4 ounces of wine, 1 ounce of spirits/hard liquor) or the participant tests positive for alcohol at screening or on day -1 of period 1.
* Participant has used any drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and/or opiates) within 3 months prior to day -1 of period 1 or the participant tests positive for drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and opiates) at screening or on day -1 of period 1.
* Participant has used any inducer of cytochrome P450 (CYP) 1A2 in the 3 months prior or inhibitors of CYP 1A2 in the 2 weeks or 5 half-lives of the inhibitor, whichever is longer, prior to day -1 of period 1.
* Participant has had significant blood loss, donated ≥ 1 unit (450 mL) of whole blood or donated plasma within 7 days prior to day 1 and/or received a transfusion of any blood or blood products within 60 days.
* Participant has a positive serology test for hepatitis A virus antibodies (immunoglobulin M), hepatitis B core antibodies, hepatitis B surface antigen, hepatitis C virus antibodies or antibodies to human immunodeficiency virus type 1 and/or type 2 at screening.
* Participant is an employee of Astellas, the study-related contract research organizations (CROs) or the clinical unit.