The purpose of AROCFB-1001 is to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of ARO-CFB Injection in adult healthy volunteers (HVs). HVs will receive either one or two doses of ARO-CFB or placebo.

Inclusion Criteria:

• Willing to provide written informed consent and to comply with study requirements
• Female participants must be non-pregnant/non-lactating
• Healthy volunteers must be willing to be vaccinated with a meningococcal and pneumococcal vaccine. IgAN participants must have been vaccinated or willing to undergo vaccination
• All participants must be willing to be vaccinated or have a history of vaccination for Haemophilus influenzae type B
• Body Mass Index (BMI) between 18.0 and 35.0 kg/m2
• Participants of childbearing potential must agree to use highly effective contraception in addition to a condom during the study and for at least 90 days following the end of the study or the last dose of study drug, whichever is later. Participants must not donate sperm or eggs during the study and for at least 90 days following the end of the study or last dose of study drug, whichever is later.
• No abnormal finding of clinical relevance at the Screening evaluation that, in the opinion of the Investigator, could adversely impact participant safety or adversely impact study results.

Exclusion Criteria:

• History of recurrent or chronic infections including infections caused by encapsulated bacterial organisms or viruses
• History of active bacterial, viral, or fungal infection within 14 days prior to treatment administrations
• Seropositive for Human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV)
• History of meningococcal infection
• History of asplenia
• History of severe aplastic anemia or concurrent severe aplastic anemia
• Known or suspected hereditary complement deficiency or other primary immunodeficiency syndrome
• History of diabetes mellitus (Type 1 or Type 2)
• Uncontrolled hypertension

Note: Additional Inclusion/Exclusion criteria may apply per protocol

Participants are randomized to receive either ARO-CFB or placebo. Participants, care providers, investigator and outcomes assessors are all blinded to treatment assignment.