This study aims to see if a new medicine called fazirsiran can help people with liver scarring from a protein problem called Alpha-1 Antitrypsin Deficiency (AATD). AATD is when a protein, alpha-1 antitrypsin, doesn't work right, leading to liver and lung issues. The study will compare fazirsiran to a placebo, which is a treatment that doesn’t contain any active medicine. Participants may need to have liver biopsies, which are small tissue samples from the liver, twice during the study. This helps check for liver scarring (fibrosis), which is a thickening or scarring of the liver due to damage. The study will look at how well fazirsiran works compared to the placebo and check for any side effects. It will also study how the body handles fazirsiran.

• The study lasts for a specific period and involves taking liver biopsies twice.
• Participants will either receive fazirsiran or a placebo.
• Participants must be between 18-75 years old and have specific liver conditions.

Participants should not have any other severe liver diseases or a history of drug abuse. They also must not have been treated with fazirsiran before.