A Study 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 trial will study the effects of single and multiple doses of ALXN1830 in healthy adult participants.

This is a Phase 1 study in healthy adult participants. The study will consist of 2 single ascending dose (Cohorts 1 and 2) and 4 multiple ascending dose cohorts (Cohorts 3 to 6). Participants will be randomly assigned to each of the 6 cohorts to receive either single or multiple doses of ALXN1830 subcutaneous (SC) or single or multiple doses of placebo SC. Cohort 6 will enroll only healthy participants of Japanese descent who will be dosed according to the highest tolerated dose (HTD) established in the non-Japanese cohorts.

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 60 to 90 kilograms (kg), inclusive, and body mass index within 18 to 30 kg/meter squared, inclusive.
• Must be willing to follow protocol-specified contraception guidance during the study and for 3 months after last dose of study drug.

Exclusion Criteria:

• Current/recurrent diseases or relevant medical history.
• Known exposure to investigational or marketed therapeutic proteins, such as monoclonal antibodies, fusion proteins, bispecific molecules, or antibody drug conjugates, within 60 days or 5 half-lives (whichever is longer) prior to dosing.
• Participants who have prior exposure to ALXN1830.
• Current enrollment or past participation within the last 90 days before signing of consent in this or any other interventional clinical study.
• Participants with hepatitis B or C, or human immunodeficiency virus.
• 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.