A Study of AMG 732 in Healthy Participants and Participants With Thyroid Eye Disease

Inclusion criteria for Part A/Phase 1 only: * Participant has provided informed consent before initiation of any study-specific activities/procedures. * Male or female aged 18 to 55 years (Part A). * Female participants must be of non-childbearing potential. * Body mass index (BMI) between 18 and 30 kg/m\^2, inclusive, at screening. * The participant has adequate venous access and can receive intravenous (IV) therapy. * The participant is considered by the investigator or designee to be in good general health as determined by medical history, clinical laboratory test results, vital sign measurements, 12-lead electrocardiogram (ECG) results, and physical examination findings at screening. * Healthy Japanese participants in cohort 4 only. Japanese participants must meet all the following as confirmed by interview: Descendants of 4 ethnic Japanese grandparents who were born in Japan; Both parents are ethnic Japanese who were born in Japan; Hold a Japanese passport or identity papers; Have lived outside Japan for less than 10 years at the time of screening and lifestyle including diet has not changed significantly since leaving Japan. Inclusion criteria for Part B/Phase 2 only: * Male or female aged 18 to 65 years. * Moderate-to-severe active TED. * The participant had onset of active TED within 15 months prior to baseline. * Clinical diagnosis of Graves' disease associated with active TED with a Clinical Activity Score (CAS)≥3 for the most severely affected eye at screening a…