A Phase 1 Trial of AMG 691 in Healthy Chinese and Japanese Volunteers

The trial is designed to evaluate the pharmacokinetics, safety, tolerability, and immunogenicity of AMG 691 in healthy Chinese and Japanese participants

Inclusion Criteria: * Healthy male or female participants, 18 to 60 years of age. * First-generation Chinese ancestry (born in China, Hong Kong, Taiwan, or Macau with 2 Chinese parents and 4 Chinese grandparents) or first-generation Japanese ancestry (born in Japan with 2 Japanese parents and 4 Japanese grandparents). * Body mass index (BMI) 18.0 to 30.0 kg/m\^2 (inclusive) and body weight ≥40 kg. * In good general health based on medical history, physical examination, vital signs, electrocardiogram (ECG), and clinical laboratory evaluations. * Female participants must not be pregnant or breastfeeding. * Participants of reproductive potential must agree to follow protocol-specified contraception requirements. * Willing to maintain usual diet and physical activity regimen throughout study participation. Exclusion Criteria: * Clinically significant medical condition, disease, or abnormal finding that could interfere with study participation or interpretation of results. * Clinically significant ECG abnormalities * Clinically significant abnormal blood pressure or pulse rate at screening/check-in. * History of malignancy (except adequately treated in situ cervical cancer or non-melanoma skin cancer \>5 years before dosing). * Deep vein thrombosis or pulmonary embolism within 3 months prior to check-in. * History of hypersensitivity/anaphylaxis to biologic therapies, mammalian-derived products, or AMG 691 excipients. * Active, chronic, recurrent, or unresolved infection; history of severe infection requiring intravenous (IV) antibiotics within the past 3 years. * Positive or indeterminate QuantiFERON-TB Gold test. * Untreated or unresolved helminth parasitic infection. * History of immunodeficiency. * Receipt of live or live-attenuated vaccines within 12 weeks before check-in or planned during the study. * Estimated glomerular filtration rate (eGFR) \1.5 × Upper Limit Normal (ULN). * Positive screening tests for human immunodeficiency virus (HIV), hepatitis B, or hepatitis C infection. * Use of prohibited prescription, over-the-counter, herbal, vitamin, or dietary supplement products within 30 days (or 5 half-lives) before enrollment, unless approved by the investigator. * History of illicit drug use within 1 year, positive drug screen, or unwillingness to abstain from illicit drugs/cannabinoids during the study. * Use of tobacco or nicotine-containing products within 6 months prior to check-in. * History of alcohol abuse or excessive alcohol consumption. * History of non-suicidal self-injury within 5 years or unstable major depressive disorder/other severe psychiatric disorder within 2 years. * Participation in another investigational drug study within 90 days (or 5 half-lives) prior to check-in. * Previous exposure to AMG 691. * Recent donation of blood, plasma, or platelets. * Any participant considered unsuitable by the investigator or unwilling to comply with study restrictions.