A Study of Multiple Doses of ALXN1210 in Healthy Adult Participants

Inclusion Criteria

• Healthy male and female participants ≥ 25 and ≤ 55 years old; smokers (no more than 10 cigarettes daily), former smokers (at the Investigator's discretion), or nonsmokers.
• Body mass index from 18 through 29.9 kilogram (kg)/square meter, inclusive, and weight between 50 and 100 kg, inclusive.
• QT interval (corrected using the Fridericia formula) ≤ 450 milliseconds (ms) for males and ≤ 470 ms for females at Screening and prior to dosing on Day 1.
• Participant was willing and able to give written informed consent and comply with the study visit schedule.
• Documented vaccination with tetravalent meningococcal conjugate vaccine (MCV4) at least 56 days and not more than 3 years prior to dosing. Documentation must have included a positive serum bactericidal antibody test to confirm an immune response before the study drug administration.
• Vaccination with serogroup B vaccine at least 56 days prior to dosing on Day 1, with a booster administered at least 28 days prior to dosing on Day 1.
• Male participants with a female spouse/partner of childbearing potential or a pregnant or breastfeeding spouse or partner were required to use barrier contraception (male condom) during the treatment period and for at least 6 months after the last dose of ALXN1210.

Exclusion Criteria

• Participants who had intimate and prolonged contact (defined as living under the same roof or providing personal care) with individuals who were either immunocompromised, or had specific underlying medical conditions (persons with anatomic or functional asplenia [including sickle cell disease]; persons with congenital complement, properdin, factor D, or primary antibody deficiencies, persons with acquired complement deficiencies [for example, those receiving eculizumab], and persons with human immunodeficiency virus [HIV]) or with persons younger than 2 years of age or older than 65 years of age
• Participants who were one of the following: professionals exposed to environments of greater risk for meningococcal disease; research, industrial, and clinical laboratory personnel routinely exposed to Neisseria meningitidis; military personnel during recruit training (military personnel may be at increased risk when accommodated in close quarters); daycare center workers; those living on a college or university campus; or those who planned to travel during the course of the study to or had travelled to endemic areas for meningococcal meningitis (for example, India, Sub-Saharan Africa, pilgrimage to Saudi Arabia for Hajj) within the past 6 months
• History of any Neisseria infection
• History of unexplained recurrent infection or infection that required treatment with systemic antibiotics within the last 90 days prior to dosing
• HIV infection (evidenced by HIV-1 or HIV-2 antibody titer)
• Acute or chronic hepatitis B virus infection (evidenced by the presence of hepatitis B surface antigen or immunoglobulin M antibodies against hepatitis B core antigen)
• Acute or chronic hepatitis C virus infection (evidenced by antibody titer)
• Active systemic viral or fungal infection within 14 days prior to dosing
• Positive or indeterminate QuantiFERON-TB test indicating possible tuberculosis infection
• History of latent or active tuberculosis or exposure to endemic areas within 8 weeks prior to the screening visit
• Female participants who were breastfeeding or were of childbearing potential, including any female who had experienced menarche and who had not undergone successful surgical sterilization (hysterectomy, bilateral tubal ligation, or bilateral oophorectomy) or who was pregnant, breastfeeding, or not postmenopausal.
• Positive serum pregnancy test at Screening or Day -1
• Serum creatinine > upper limit of normal (ULN) of the reference range of the testing laboratory at Screening or Day -1.
• Alanine aminotransferase or aspartate aminotransferase > ULN of the reference range of the testing laboratory at Screening or > 1.5*ULN of the reference