The FDA approval of Onpattro (patisiran) infusion, from Alnylam Pharmaceuticals, while expected, nevertheless is generating considerable buzz in pharmaceutical circles. The therapy is intended for a rare condition called hATTR (hereditary transthyretin-mediated amyloidosis); it addresses the polyneuropathy caused by the condition, and is the first such treatment. It is also the first FDA approval of a new class of drugs called small interfering ribonucleic acid (siRNA) treatment; more generally called RNA inhibitors, that alter the genetic drivers of a disease. Such siRNAs work by silencing a portion of RNA involved in causing the disease, according to the FDA approval announcement. More specifically, Onpattro encases the siRNA into a lipid nanoparticle to deliver the drug directly into the liver, in an infusion treatment, to alter or halt the production of disease-causing proteins. As such, they have the potential to provide a cure, and not just addressing the symptoms of the disease.