On August 10, 2018, the Food and Drug Administration (FDA) gave approval to Alnylam Pharmaceuticals for the use of Onpattro (patisiran) lipid complex injection, a drug developed to treat hereditary transthyretin-mediated amyloidosis (hATTR) in adults. Specifically, Onpattro treats polyneuropathy developed due to the disease. Alnylam Pharmaceuticals submitted the New Drug Application for Onpattro on December 11, 2017. This is the first FDA approval of a small interfering ribonucleic acid (siRNA) treatment, which represents a new class of drugs for FDA approval.
Generally, siRNA treatments work by targeting and blocking expression of specific RNAs that contribute to a disease. Unlike gene editing, which alters the DNA, siRNA functions by interfering with RNA to halt problematic expression. Individuals with hATTR have a mutation in the TTR gene which ultimately produces an accumulation of transthyretin (TTR) protein. This accumulation leads to a cluster of amyloid deposits in nerves, which triggers polyneuropathy. Onpattro was developed to block the production of TTR to reduce polyneuropathy associated with hATTR. The FDA notes that approval of this drug represents a new chapter in RNA interference drugs with the potential to treat diseases by targeting their root causes rather than the associated symptoms.