Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of ASP5354 in Healthy Adult Japanese Male Participants

This study is comprised of 3 parts. Part 1 and Part 2 will be conducted in a parallel manner while Part 3 will be conducted subsequentially. Participants will be residential for a period of 3 days/2 nights. Participants will be discharged from the clinical unit on day 2 on the condition that all required assessments have been performed and that there are no medical reasons for a longer stay in the clinical unit.

Inclusion criteria

• Participant has a body mass index (BMI) range of 17.6 to 26.4 kg/m^2 inclusive and weighs at least 50 kg at screening.
• Male participant with female partner(s) of childbearing potential (including breastfeeding partner) must agree to use contraception throughout the treatment period and for 30 days after Investigational Product (IP) administration.
• Male participant must not donate sperm during the treatment period and for 30 days after IP administration.
• Male participant with pregnant partner(s) must agree to remain abstinent or use a condom for the duration of the pregnancy throughout the study period and for 30 days after 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 12 weeks prior to screening.
• Participant has any condition that makes the participant unsuitable for study participation.
• Participant has a known or suspected hypersensitivity to ASP5354 or any components of the formulation used.
• Participant has had previous exposure with ASP5354.
• Participant has any of the liver function tests (alkaline phosphatase [ALP], alanine aminotransferase [ALT], aspartate aminotransferase [AST] and total bilirubin [TBL]) above the upper limit of normal (ULN) on day -1. In such a case, the assessment may be repeated once.
• Participant has creatinine level outside normal limits on day -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 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.
• Participant has any clinically significant abnormality following the physical examination, electrocardiogram (ECG) and protocol-defined clinical laboratory tests at screening or on day -1.
• Participant has a mean pulse < 40 or > 100 bpm; mean systolic blood pressure (SBP) < 90 or > 140 mmHg; mean diastolic blood pressure (DBP) < 40 or > 90 mmHg (measurements taken in triplicate after participant has been resting in the supine position for at least 5 minutes; pulse will be measured automatically) on day-1. If the mean blood pressure exceeds the limits above, one additional triplicate may be taken.
• Participant has body temperature < 35.0ºC or >= 37.5ºC on day -1.
• Participant has a mean corrected QT interval using Fridericia's formula (QTcF) of > 430 msec on day -1. If the mean QTcF exceeds the limits above, one 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 IP administration, except for occasional use of acetaminophen (up to 2 g/day) and topical dermatological products (including corticosteroid products).
• Participant has a history of smoking > 10 cigarettes (or equivalent amount of tobacco) per day within 3 months prior to day -1.
• Participant has a history of consuming > 16 units of alcohol per week within 3 months prior to day -1 (note: 1 unit = 10 g pure alcohol, = 250 mL of beer [5%], 35 mL of spirits [35%] or 100 mL of wine [12%]).
• Participant has used any drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and/or morphine and phencyclidines) within 3 months prior to day -1 or the participant tests positive for drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and morphine, phencyclidines) at screening or on day -1.
• Participant has used any inducer of metabolism (e.g., barbiturates and rifampin) in the 3 months prior to day -1.
• Participant has had significant blood loss, donated >= 400 mL of whole blood within 90 days, >= 200 mL of whole blood within 30 days or donated blood components within 14 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 B core (HBc) antibodies, hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies and antigen or antibodies to human immunodeficiency virus (HIV) type 1 and/or type 2 and syphilis at screening.
• Participant is an employee of Astellas, the study-related contract research organizations (CROs) or the clinical unit.