Alnylam Dealt Setback in Quest to Expand Heart Drug’s Uses

(Bloomberg) -- Alnylam Pharmaceuticals Inc. shares fell after a trial of its drug to treat a deadly form of heart disease fell short of investors’ expectations. 

Wall Street anticipated Alnylam’s drug, Amvuttra, to rapidly outperform placebo in a study measuring its effects on cardiovascular health and survival. Instead, the medicine was similar to a Pfizer Inc. treatment and another drug under development from BridgeBio Pharma Inc.

The shares were down as much as 9.1% when US markets opened, their biggest intraday loss since February. BridgeBio’s shares rose as much as 15%.

The detailed data follow results disclosed in June. That successful trial sent Alnylam’s shares soaring after its drug benefited patients with the heart condition known as ATTR amyloidosis with cardiomyopathy. 

Alnylam is seeking to expand the use of Amvuttra, which has been approved to treat a similar disorder in which abnormal proteins damage multiple organs and tissues, including nerves. The drug, expected to win US approval for ATTR-CM next year, could bring in peak sales of about $4 billion a year, according to analysts at William Blair. 

The goal of the study was for the drug to reduce death and hospitalizations in patients with the heart condition, even if they were already taking Pfizer’s drug, marketed as Vyndaqel and Vyndamax. Alnylam said its drug achieved a 28% reduction in death and heart-related hospitalizations among all patients in the trial and a 33% reduction for those who weren’t on the Pfizer drug. 

Alnylam’s results were presented Friday at the European Society of Cardiology conference in London. The shares fell as much as 21% in trading before US markets opened, then pared most of those losses after the company corrected a number given by a researcher at the conference in an analysis that made Alnylam’s drug appear inferior to competitors’.

The study included 655 adults who received either Alnylam’s treatment or a placebo once every three months for as long as three years. About 40% of patients were taking Pfizer’s treatment at the outset of the trial, and another 20% started receiving it during the study.

Once thought to be rare, ATTR-CM is being diagnosed more frequently thanks to advances in testing, making it a popular target for drugmakers. More than 300,000 patients globally have the condition, according to Alnylam. Other companies developing treatments include Ionis Pharmaceuticals Inc. and Intellia Therapeutics Inc.

(Updates with shares, additional detail from second paragraph.)

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