A Study to Assess Bioavailability of Rocatinlimab (AMG 451) Vial and Prefilled Syringe in Healthy Participants

Inclusion Criteria 1. Participant has provided informed consent before initiation of any study-specific activities/procedures. 2. Healthy male or female participants, between 18 and 65 years of age (inclusive) 3. Body mass index between 18 and 32 kg/m^2 (inclusive) Exclusion Criteria 1. History or evidence, at Screening or Check-in, of clinically significant disorder, condition, or disease not otherwise excluded that, in the opinion of the Investigator (or designee), would pose a risk to participant safety or interfere with the study evaluation, procedures, or completion. 2. History or evidence of clinically significant arrhythmia at Screening, including any clinically significant findings on the electrocardiogram (ECG) taken at Check-in. 3. A QT interval corrected for heart rate using Fridericia’s method (QTcF) > 450 msec in male participants or > 470 msec in female participants or history/evidence of long QT syndrome at Screening or Check-in. 4. Systolic blood pressure > 140 mmHg or < 90 mmHg, or diastolic blood pressure > 90 mmHg, or pulse rate > 100 bpm 5. History of hypersensitivity, intolerance, or allergy to any drug compound, food, or other substance, unless approved by the Investigator (or designee). Participants with seasonal allergies will be permitted. 6. Estimated glomerular filtration rate less than 70 mL/min/1.73 m^2 7. Alanine aminotransferase or aspartate aminotransferase > 1.5 times the upper limit of normal at Screening or Check-in. 8. Positive hepatitis B or hepatitis C panel (including positive hepatitis B surface antigen [HBsAg] and/or positive hepatitis C antibody) and/or positive human immunodeficiency virus test at Screening. Participants whose results are compatible with prior hepatitis B vaccination (positive hepatitis B surface antibody, negative hepatitis B core antibody, negative HBsAg) or prior infection (positive hepatitis B core antibody, positive hepatitis B surface antibody, negative HBsAg) may be included. 9. Participants who have received live vaccines within 5 weeks prior to Screening, or plan to receive live vaccines within 90 days after administration of an investigational product. Inactive vaccination (e.g., non-live or nonreplicating agent), including coronavirus-2019 (COVID-19) vaccination, is allowed. 10. History of latent tuberculosis or active chronic, recurrent, or acute infection requiring treatment with systemic antibiotics, antiviral, antiparasitic, antiprotozoal, or antifungals which has not completely resolved, or for which therapy has not been completed, within 4 weeks before Screening. 11. Use of any over-the-counter or prescription medications within 30 days or 5 half-lives (whichever is longer) before Check-in, excluding the following: a. Acetaminophen (paracetamol) (up to 2 g per day) for analgesia will be allowed. b. Hormonal contraception listed in Appendix 3 will be allowed. c. Hormone replacement therapy (e.g., estrogen) and hormonal contraceptives will be allowed. 12. All herbal medicines (e.g., St. John’s wort), vitamins, and supplements consumed by the participant within the 30 days prior to Check-in, unless deemed acceptable by the Investigator (or designee) and in consultation with the Sponsor. 13. Participant has received a dose of an investigational drug within the past 90 days or 5 half-lives, whichever is longer, prior to Check-in. 14. Have previously completed or withdrawn from this study or any other study investigating rocatinlimab or have previously received rocatinlimab.