Study of Subcutaneous and Intravenous ALXN1720 With and Without rHuPH20 in Healthy Subjects

A Phase 1, Randomized, Double-blind, Placebo-controlled, Single and Multiple Ascending Dose Study of Subcutaneous and Intravenous ALXN1720 With and Without rHuPH20 in Healthy Subjects

This study is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity of ALXN1720 administered subcutaneously (SC) or intravenously (IV).

Participants will be randomized in a 3:1 ratio to receive the active treatment or placebo.

The study will be conducted in healthy adult participants, including participants of Japanese descent.

Inclusion Criteria:

• Body weight within 50 to 90 kilograms (kg), inclusive, and body mass index within the range of 18 to 29.9 kg/meter squared, inclusive.
• Willing to follow protocol-specified contraception guidance while on treatment and for 6 months after the last dose of study treatment.
• Vaccination with tetravalent meningococcal conjugate vaccine and serogroup B meningococcal vaccine.
• No clinically significant or relevant abnormalities as determined by medical history, physical examination, vital signs, 12-lead electrocardiogram, and clinical laboratory evaluation.
• For the cohorts with Japanese participants, parents and grandparents must both be Japanese, and participants must have resided for less than 5 years outside of Japan.

Exclusion Criteria:

• Current or recurrent disease that could affect clinical assessments or clinical laboratory evaluations.
• History of complement deficiency or complement activity below the reference range.
• Female participants who are breastfeeding.
• Immunization with a live-attenuated vaccine 28 days prior to dosing on Day 1 or planned vaccination during the course of the study. Immunization with inactivated or recombinant influenza vaccine, or nucleoside-modified messenger ribonucleic acid or recombinant COVID-19 vaccine is permitted.
• Current tobacco smoking, history of illicit drug abuse, or history of significant alcohol abuse.