The U.S. Food and Drug Administration today approved Onpattro (patisiran) infusion for the treatment of peripheral nerve disease (polyneuropathy) caused by hereditary transthyretin-mediated amyloidosis (hATTR) in adult patients. This is the first FDA-approved treatment for patients with polyneuropathy caused by hATTR, a rare, debilitating and often fatal genetic disease characterized by the buildup of abnormal amyloid protein in peripheral nerves, the heart and other organs. It is also the first FDA approval of a new class of drugs called small interfering ribonucleic acid (siRNA) treatment.
Mechanism of action:
- RNA acts as a messenger within the body’s cells, carrying instructions from DNA for controlling the synthesis of proteins. RNA interference is a process that occurs naturally within our cells to block how certain genes are expressed.
- This new class of drugs, called siRNAs, work by silencing a portion of RNA involved in causing the disease. 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.
- Onpattro is designed to interfere with RNA production of an abnormal form of the protein transthyretin (TTR). By preventing the production of TTR, the drug can help reduce the accumulation of amyloid deposits in peripheral nerves, improving symptoms and helping patients better manage the condition.
The FDA granted this application Fast Track, Priority Review and Breakthrough Therapy designations. Onpattro also received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.
The efficacy of Onpattro was shown in a clinical trial involving 225 patients, 148 of whom were randomly assigned to receive an Onpattro infusion once every three weeks for 18 months, and 77 of whom were randomly assigned to receive a placebo infusion at the same frequency. The patients who received Onpattro had better outcomes on measures of polyneuropathy including muscle strength, sensation (pain, temperature, numbness), reflexes and autonomic symptoms (blood pressure, heart rate, digestion) compared to those receiving the placebo infusions. Onpattro-treated patients also scored better on assessments of walking, nutritional status and the ability to perform activities of daily living.
Approval of Onpattro was granted to Alnylam Pharmaceuticals, Inc.