The FDA approved patisiran infusion for the treatment of adults with polyneuropathy caused by hereditary transthyretin-mediated amyloidosis.
The approval of patisiran (Onpattro, Alnylam Pharmaceuticals) marks the first FDA-approved treatment for this disease, as well as the first approval of a new class of drugs called small interfering ribonucleic acid treatment.
“This approval is part of a broader wave of advances that allow us to treat disease by actually targeting the root cause, enabling us to arrest or reverse a condition, rather than only being able to slow its progression or treat its symptoms,” FDA Commissioner Scott Gottlieb, MD, said in a press release. “In this case, the effects of the disease cause a degeneration of the nerves, which can manifest in pain, weakness and loss of mobility.”
Hereditary transthyretin-mediated amyloidosis affects about 50,000 people worldwide. It is characterized by the buildup of abnormal deposits of amyloid protein fibers in the body's organs and tissues. The deposits frequently occur in the peripheral nervous system — causing a loss of sensation, pain or immobility — but can also affect heart, kidney, eye and gastrointestinal function.
Patisiran interferes with RNA production of the transthyretin protein, which can help reduce the accumulation of amyloid deposits.
The FDA based the approval of patisiran for the treatment of polyneuropathy on a trial of 225 patients. Researchers randomly assigned patients to receive either patisiran infusion (n = 148) every 3 weeks for 18 months or placebo (n = 77).
All patients who participated in the clinical trials received premedication with a corticosteroid, acetaminophen and antihistamines to reduce risk for infusion-related reactions.
Patients assigned patisiran had better outcomes related to polyneuropathy, including muscle strength, sensation (pain, temperature, numbness), reflexes and autonomic symptoms (blood pressure, heart rate, digestion) compared with those assigned placebo.
Results also showed patients assigned patisiran had improved assessments of walking, nutritional status and the ability to perform daily activities.
The most common adverse reactions associated with patisiran included flushing, back pain, nausea, abdominal pain, dyspnea and headache. Patients also reported vision problems including dry eyes, blurred vision and vitreous floaters.
Researchers recommended patients take a daily vitamin A supplement while undergoing treatment with patisiran, as the agent leads to a decrease in serum vitamin A levels.
“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 at the FDA, said in the release. “This unique targeted therapy offers these patients an innovative treatment for their symptoms that directly affects the underlying basis of this disease.”
The FDA granted this application fast track, orphan drug, priority review and breakthrough therapy designations.