Safety, Tolerability and Pharmacodynamic Effect of Fazirsiran (TAK-999, ARO-AAT)

Participants will be enrolled to receive multiple subcutaneous injections of Fazirsiran Injection (also referred to as TAK‐999 Injection or ARO‐AAT Injection) or placebo. Eligible participants will require a pre‐dose biopsy completed as part of the study within the screening window. However, any participant with a biopsy result within 1 year of screening showing no fibrosis does not require a pre‐dose biopsy. Only participants who have liver fibrosis will undergo a post‐dose biopsy and may continue treatment in an open‐label phase.