A Study of Single and Multiple SC Doses of ALXN1830 in Healthy Adult Participants

A Phase 1, Randomized, Double-Blind, Placebo-Controlled, Single and Multiple Ascending Dose Study of Subcutaneous ALXN1830 in Healthy Participants

This study will evaluate the effects of single ascending doses (SAD) and multiple ascending doses (MAD) of ALXN1830 administered subcutaneously (SC) to healthy adult participants.

This Phase 1 study will consist of 3 SAD (Cohorts 1 to 3) and 4 MAD (Cohorts 4 to 7) cohorts. Participants will be randomly assigned in a 6:2 ratio to each of the 7 cohorts to receive either single or multiple doses of ALXN1830 (n = 6 per cohort) or single or multiple doses of placebo (n = 2 per cohort).

Inclusion Criteria:

• Satisfactory medical assessment.
• Participants must have had vaccination against pneumococcus (Pneumovax 23 [PPSV23]) at least 28 days, and maximally 4 years prior to Day 1.
• Participants must have had seasonal influenza vaccination for the current season at least 28 days prior to Day 1.
• Body weight within 50 to 90 kg, inclusive, and body mass index (BMI) within the range of 18 to 24.9 kg/m^2, inclusive.
• Must be willing to follow protocol-specified contraception guidance during the study and for up to 3 months after last dose of study drug.

Exclusion Criteria:

• Current/recurrent diseases or relevant medical history.
• Known exposure to therapeutic proteins, such as monoclonal antibodies, including marketed drugs prior to dosing.
• Participants who have prior exposure to ALXN1830.
• Exposure to more than 4 new (small molecule) investigational compounds within 12 months prior to dosing.
• Current enrollment or past participation within the last 90 days before signing of consent in this or any other interventional clinical study.
• Presence of hepatitis B surface antigen (HBsAg) at Screening.
• Positive hepatitis C antibody test result at Screening.
• Positive human immunodeficiency virus (HIV) antibody test at Screening.
• Participants who are either immunocompromised or have one of the following underlying medical conditions: anatomic or functional asplenia (including sickle cell disease); primary antibody deficiencies