RNAi therapeutics for diseases involving protein aggregation: fazirsiran for alpha-1 antitrypsin deficiency-associated liver disease.

When certain proteins in the body are not produced correctly, it can result in disease. Examples of such diseases include alpha-1 antitrypsin deficiency (AATD), hereditary transthyretin amyloidosis (ATTR), amyotrophic lateral sclerosis (ALS), Alzheimer's disease, and Parkinson's disease, where misfolded proteins can form harmful aggregates. Research is underway to develop new therapies such as small interfering RNA (siRNA), antisense oligonucleotides, monoclonal antibodies, clustered regularly interspaced short palindromic repeats (CRISPR), and small molecule protein modulators to prevent protein aggregates. An example of an experimental siRNA therapy for patients with AATD is fazirsiran, designed to prevent the production of mutated alpha-1 antitrypsin (Z-AAT) and allows the liver to clear previously accumulated Z-AAT protein, which is believed to be responsible for causing AATD liver disease. This review summarizes the development of fazirsiran and describes how it helps our understanding and treatment of diseases associated with protein aggregation.