US regulators have expressed doubts about the effectiveness of a drug developed by Alnylam Pharmaceuticals Inc. The company is seeking approval to expand the use of its drug, Onpattro, to treat a heart muscle disease known as cardiomyopathy. In documents released by the US Food and Drug Administration (FDA) prior to a meeting with Alnylam and expert advisors, it was stated that the drug's effects compared to a placebo were "small, of questionable clinical meaningfulness, and may not be detectable by patients." However, no major safety concerns were identified.
Onpattro, which is administered through infusion, was originally approved in 2018 as a groundbreaking treatment for a rare genetic disease called polyneuropathy. It is the first drug in the small interfering ribonucleic acid (siRNA) class to receive FDA approval. Polyneuropathy is characterized by the accumulation of abnormal amyloid protein in peripheral nerves, the heart, and other organs.
Alnylam is now seeking approval for Onpattro's use in improving symptoms of a specific type of cardiomyopathy caused by the buildup of amyloid protein in the heart. This condition can lead to heart failure. A group of FDA advisors is scheduled to meet on Wednesday to review the evidence presented by Alnylam in support of the expanded usage. The FDA is likely to reach a decision on whether to approve the expanded use of Onpattro by early next month.
Despite the concerns raised by the FDA, some analysts remain confident that the drug will ultimately receive approval. RBC Capital Markets analyst Luca Issi believes that the drug will be approved because it is considered safe and has met primary and secondary endpoints.
Currently, Pfizer Inc.'s Vyndaqel and Vyndamax are the only approved medications for treating adults with this type of cardiomyopathy. The genetic form of the disease is estimated to affect around 50,000 patients worldwide, while the wild-type, which mainly affects older men, is likely to be more common but under-diagnosed.
Alnylam's shares saw a modest 0.6% increase following the news.