First Targeted Treatment of Polyneuropathy in Rare Disease Wins FDA Approval


Patisiran (Onpattro, Alnylam Pharmaceuticals) is indicated for the treatment of adult patients with polyneuropathy caused by hereditary transthyretin-mediated amyloidosis (hATTR), a rare genetic disease.

Officials with the FDA have approved the first targeted treatment for adult patients with polyneuropathy caused by hereditary transthyretin-mediated amyloidosis (hATTR), a rare and often fatal disease, according to a press release.

Although rare, affecting approximately 50,000 people worldwide, hATTR can be debilitating—interfering with normal functioning through the buildup of abnormal deposits of protein fibers called amyloid in the body’s organ and tissues. As a result, patients may experience loss of sensation, pain, or immobility in the arms, legs, hands, and feet These deposits can also affect the functioning of the heart, kidneys, eyes, and gastrointestinal tract.

The drug, patisiran (Onpattro, Alnylam Pharmaceuticals) infusion, is the first to be approved of a new class called small interfering ribonucleic acid (siRNA) treatment. This new drug class works by silencing a portion of RNA involved in causing the disease, according to the FDA. Specifically, treatment is designed to interfere with RNA production of an abnormal form of the protein transthyretin (TTR) to reduce the accumulation of amyloid deposits in peripheral nerves.

The approval is based efficacy data from a clinical trial involving 225 patients, 148 of whom were randomly assigned to receive patisiran infusion once every 3 weeks for 18 months, and 77 of whom were randomly assigned to receive a placebo infusion at the same frequency. According to the data, patisiran-treated patients had better outcomes on measures of polyneuropathy, including muscle strength, sensation, reflexes, and autonomic symptoms compared with patients who received the placebo. Patients who received patisiran also scored better on assessments of walking, nutritional status, and the ability to perform activities of daily living.

“There has been a long-standing need for a treatment for hereditary transthyretin-mediated amyloidosis polyneuropathy,” Billy Dunn, MD, director of the Division of Neurology Products in the FDA’s Center for Drug Evaluation and Research, said in a statement. “This unique targeted therapy offers these patients an innovative treatment for their symptoms that directly affects the underlying basis of this disease.”

Common adverse effects reported by patients treated with patisiran are infusion-related reactions including flushing, back pain, nausea, abdominal pain, dyspnea, and headache. Patients may also experience vision problems and decreased serum vitamin A levels, according to the FDA.


FDA approves first-of-its kind targeted RNA-based therapy to treat a rare disease [news release]. FDA’s website. Accessed August 10, 2018.

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