Alnylam gives up on expanded use of heart-disease drug in US after FDA declines approval

[October 10, 2023]  By Mariam Sunny

(Reuters) -Alnylam Pharmaceuticals said on Monday it would not pursue expanded use of its drug to treat a potentially fatal heart disease in the U.S. after the Food and Drug Administration declined to approve the medication despite a favorable recommendation from its advisers.

Shares of the Massachusetts-based company were down nearly 6% in early trading.

The regulator, in its so-called complete response letter, said the drug patisiran did not meaningfully improve the condition of patients with heart muscle issues or cardiomyopathy caused by ATTR amyloidosis, characterized by abnormal deposits of transthyretin proteins in organs and tissues.

Patisiran, also branded as Onpattro, is already approved in the U.S. to treat nerve damage in adult patients with hereditary ATTR amyloidosis. The FDA's decision would not impact Onpattro's commercial availability, Alnylam said.

The rejection was a rare instance of the regulator going against its advisory panel's backing for a drug. The FDA's outside panel of experts had last month backed patisiran's expanded use, but also raised concerns about the meaningfulness of its benefits.

"We are surprised" by the FDA's decision, RBC capital analyst Luca Issi said in a note.

Signage is seen outside of the Food and Drug Administration (FDA) headquarters in White Oak, Maryland, U.S., August 29, 2020. REUTERS/Andrew Kelly/File Photo

The FDA, however, did not identify any issues with the drug's safety, quality, study conduct, or manufacturing, the company said.

The FDA, in 2019, approved Pfizer's oral drug tafamidis, sold under the brand names Vyndaqel and Vyndamax, to treat transthyretin amyloid cardiomyopathy in the United States.

Alnylam said it will focus on another drug candidate, vutrisiran, an under-the-skin injection in late-stage trials to treat ATTR amyloidosis-related cardiomyopathy.

Branded as Amvuttra, vutrisiran is also approved in the U.S. to treat nerve damage in adult patients with hereditary ATTR amyloidosis.

William Blair analyst Myles Minter estimates peak U.S. sales of $2.2 billion for vutrisiran as an ATTR cardiomyopathy treatment.

(Reporting by Mariam Sunny in Bengaluru; Editing by Pooja Desai)

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