Safety and Tolerability, Pharmacokinetic, and Pharmacodynamic Study of ALXN1920 in Healthy Participants

This study will assess the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of single ascending doses (SADs) of ALXN1920 subcutaneous (SC) and of a single dose of ALXN1920 intravenous (IV) in healthy adult participants.

Inclusion Criteria:Healthy participantsBody mass index within 18.0 to 32.0 kg/m^2 (inclusive), with a minimum body weight of 50.0 kg.Female participants of childbearing potential and male participants must follow protocol-specified contraception guidance.For Cohort 6, participants of Japanese descent, defined as having both parents and 4 grandparents who are ethnically Japanese.Exclusion Criteria:Significant history or current cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrinological, hematological, or neurological disorders.History of significant allergic reaction.History of any Neisseria infectionActive systemic bacterial, viral, or fungal infection.Participants who at Day -1 are either testing positive for coronavirus disease 2019 (COVID-19), or have not had at least 4 weeks elapse of recovery time (a negative test), or are experiencing long-term COVID-19-related sequelae.Any major surgery within 8 weeks of Screening.Known or suspected history of drug or alcohol abuse.Current tobacco users or smokers.Positive Human immunodeficiency virus (HIV) infection, hepatitis B or hepatitis C viral infection.Female participant who are pregnant, breastfeeding, or intending to conceive during the course of the study.