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.

This is a first-in-human study in healthy adult participants. Eligible participants will be randomly assigned in a 3:1 (ALXN1920:Placebo) ratio in each of the treatment cohorts. The first 2 participants randomized to each cohort will be dosed as a sentinel pair, with 1 participant on active treatment and 1 participant on placebo. At the discretion of the Investigator, up to 3 more participants will be added at least 48 hours after the dosing of the sentinel pair, followed by dosing of the remaining participants in the cohort no earlier than 72 hours after sentinel pair dosing. The study will comprise: A Screening Period of up to 28 days; A Dosing Period (single dose through to Follow-up Visit) of approximately 28 days; A Final Follow-up period and end of study Visit is planned on Day 29. Each participant will be involved in the study for approximately 56 days.