Alnylam Pharmaceuticals has obtained approval from the US Food and Drug Administration (FDA) for Onpattro (patisiran) to treat peripheral nerve disease (polyneuropathy) in adults with hereditary transthyretin-mediated amyloidosis (hATTR).

Onpattro is the first FDA-approved medicine for this indication. It also the first drug to secure authorisation under the new small interfering ribonucleic acid (siRNA) drugs class.

The siRNA mechanism involves silencing of a RNA portion related to pathogenesis of the disease.

Onpattro is designed to encase the siRNA into a lipid nanoparticle for direct delivery of the drug into the liver in order to change or stop the production of disease-causing protein called transthyretin (TTR).

By halting the TTR production, the medicine can help decrease the accumulation of amyloid deposits in peripheral nerves.

FDA Division of Neurology Products director Billy Dunn said: “There has been a long-standing need for a treatment for hereditary transthyretin-mediated amyloidosis polyneuropathy.

“This unique targeted therapy offers these patients an innovative treatment for their symptoms that directly affects the underlying basis of this disease.”

“There has been a long-standing need for a treatment for hereditary transthyretin-mediated amyloidosis polyneuropathy.”

Onpattro’s efficacy was validated in a clinical trial called APOLLO performed in a total of 225 patients. The trial involved administration of the drug once every three weeks for 18 months.

Compared to the placebo groups, participants treated with Onpattro had better outcomes on polyneuropathy measures, such as muscle strength, sensation, reflexes and autonomic symptoms.

Onpattro also demonstrated favourable profile in assessments of walking, nutritional status and ability to perform daily activities.

The most common adverse reactions with Onpattro were found to be infusion-related, including flushing, back pain, nausea, abdominal pain, difficulty breathing and headache.

hATTR is a rare, debilitating genetic condition that results in build-up of abnormal amyloid protein in peripheral nerves and other organs, including heart. It affects around 50,000 people globally.

The FDA had previously granted Onpattro fast track, priority review, breakthrough therapy and orphan drug designations.