June 24 (Reuters) - Alnylam Pharmaceuticals (ALNY.O) New Tab, opens new tab said on Monday that its drug vutrisiran helped reduced the number of deaths and cardiovascular events in a study of patients with a rare heart disease, sending the drugmaker's shares up 39% in premarket trading.

The study enrolled 655 patients who were randomized to receive Alnylam's drug or placebo. Some patients were given an approved drug, Pfizer's (PFE.N) New Tab, opens new tab tafamadis, at the beginning of the study.

Data from a keenly-awaited trial showed that vutrisiran helped reduce deaths by all causes and heart-related events by 28% across all trial patients and by 33% in patients who only received vutrisiran.

Stifel analyst Paul Matteis said that data supports the drug's potential to become a blockbuster treatment.

Treatment with the drug also resulted in statistically significant improvements across all secondary goals, including measures such as the distance patients could walk in six minutes - a key measure of disease progression.

The study tested adults with transthyretin amyloid cardiomyopathy (ATTR-CM), where function of the heart muscles is restricted due to the accumulation of irregular proteins.

The company said that ATTR-CM affects about 200,000-300,000 people worldwide. William Blair analysts forecast the market for ATTR treatments to be a $10 billion opportunity for drugmakers.

Current treatment options include Pfizer's tafamidis, which is sold as Vyndaqel and Vyndamax. BridgeBio (BBIO.O) New Tab, opens new tab and Ionis Pharmaceuticals (IONS.O) New Tab, opens new tab are also developing rival treatments for ATTR-CM.

Stifel's Matteis added that it was hard to directly compare Alnylam's drug data with Pfizer's tafamidis and BridgeBio's acoramidis due to the limited details disclosed.

BridgeBio shares fell 7% to $25.44 in premarket trade.

Massachussets-based Alnylam said it will begin submitting data to regulatory bodies worldwide, including to the U.S. Food and Drug Administration, later this year.

Vutrisiran is approved in the U.S. under the brand name Amvuttra to treat nerve damage in adult patients for another condition known as hereditary ATTR amyloidosis.

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https://www.reuters.com/business/healthcare-pharmaceuticals/alnylams-heart-disease-drug-meets-main-goal-late-stage-study-2024-06-24/