(Bloomberg) -- Alnylam Pharmaceuticals Inc. shares soared after its drug succeeded in treating a progressive and deadly form of heart disease, potentially opening up a new avenue for the company’s top-selling product.

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A study released Monday found that Alnylam’s vutrisiran, which is sold as Amvuttra, helped patients with a serious heart condition known as known as ATTR amyloidosis with cardiomyopathy. The goal of the study was for the drug to reduce death and hospitalizations in patients with the condition who were taking a Pfizer Inc. drug approved for it, as well as in those not on Pfizer’s drug.

Alnylam said its drug achieved a 28% and 33% reduction in death and heart-related hospitalizations in those two groups of patients, respectively. The study included 655 adults who took either Alnylam’s drug or a placebo once every three months for as long as three years. Alnylam said its drug showed “encouraging” safety and tolerability and that it plans to move forward with its regulatory approval filing later this year.

“We really feel that this data has set the bar for a new standard of care,” Alnylam Chief Executive Officer Yvonne Greenstreet said in an interview.

Alnylam shares jumped as much as 33% after markets opened, the most intraday in nearly two years. Before Monday, the stock had fallen 13% since the start of this year.

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 BridgeBio Pharma Inc., Ionis Pharmaceuticals Inc. and Intellia Therapeutics Inc.

William Blair analyst Myles Minter called the results a “a clear home run” for Alnylam and a positive sign for Ionis and Intellia that want to treat the condition with a similar approach. Intellia shares rose as much as 11% after the markets opened while Ionis shares increased 5%.

BridgeBio shares were down as much as 19%, the biggest intraday decline in nearly two years. After Alnylam’s results, Mizuho analyst Jared Holz said the bar for BridgeBio’s treatment is “now a bit higher.” Last year, BridgeBio reported positive results in a late-stage study of its drug for the same condition. US regulators are expected to decide whether to approve that drug by late November.

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.

Greenstreet said expanding use of the drug “really unlocks the potential for significant revenue growth” and called the results “a really important moment for the company.”

“We believe we have in our hands a multibillion-dollar opportunity,” she said.

In 2019, US regulators approved a Pfizer drug to treat the same heart condition. Analysts expect it to generate more than $4 billion in sales this year.

--With assistance from Madison Muller.

(Updates with latest stock prices for other companies in paragraphs 7 and 8.)

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