Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), the leading RNAi therapeutics company, today announced it will present new data analyses for vutrisiran in patients with the cardiomyopathy of wild-type or hereditary transthyretin-mediated amyloidosis (ATTR-CM) at Heart Failure 2026, a scientific congress of the European Society of Cardiology, taking place May 9-12, 2026, in Barcelona, Spain.

ATTR-CM is a heterogeneous and rapidly progressive disease, and patients often present with complex clinical profiles. At Heart Failure 2026, Alnylam will present multiple new analyses from the Phase 3 HELIOS-B study of vutrisiran, which continue to support its use as a first-line treatment for patients with ATTR-CM, and further characterize its clinical profile across patients with a high disease burden, and in the context of concomitant therapies. Vutrisiran is the first and only transthyretin (TTR) silencer for ATTR-CM that delivers rapid knockdown of TTR at the source.

Additional analyses being presented at the congress include a pharmacodynamic analysis of TTR knockdown with vutrisiran across subgroups, a pooled safety analysis evaluating the incidence of TTR lowering with vitamin-A-related outcomes across clinical trial and real-world datasets, as well as the design of DemonsTTRate, a global, long-term observational study evaluating real-world use in patients with ATTR-CM.

Presentation Details

Design and Rationale of DemonsTTRate: A Global, Long-Term Observational Study to Evaluate Vutrisiran in Patients with Transthyretin Amyloidosis with Cardiomyopathy
Session: Evolving management of cardiomyopathies: early detection, precision diagnostics, and emerging treatments (Moderated ePosters 3)
Sunday, May 10, 08:30 – 09:15 CEST, 2:30 – 3:15 A.M. EST
Presenting Author: Pablo Garcia-Pavia, Spain

Influence of Vutrisiran on Systolic Blood Pressure in ATTR-CM: Insights From HELIOS-B
Session: Cardiac amyloidosis: therapeutic strategies and clinical outcomes (Moderated ePosters 4)
Sunday, May 10, 15:30 – 16:15 CEST, 9:30 – 10:15 A.M. EST
Presenting Author: Awais Sheikh, United Kingdom

Effect of Vutrisiran in Patients with and without Atrial Fibrillation or Flutter: Analysis from HELIOS-B
Session: Advances in amyloidosis and hypertrophic cardiomyopathy: from diagnosis to treatment (Moderated ePosters 2)
Monday, May 11, 10:30 – 11:15 CEST, 4:30 – 5:15 A.M. EST
Presenting Author: Xiaowen Wang, United States of America

Treatment with Transthyretin-Lowering RNA Interference Therapeutics is Not Associated with Ocular or Other Clinical Events Due to Vitamin A Reduction: Pooled Analysis of Vutrisiran and Patisiran Data
Session: Advances in amyloidosis and hypertrophic cardiomyopathy: from diagnosis to treatment (Moderated ePosters 2)
Monday, May 11, 10:30 – 11:15 CEST, 4:30 – 5:15 A.M. EST
Presenting Author: Mathew Maurer, United States of America

Vutrisiran-Mediated Knockdown of Transthyretin in Patients with Transthyretin Amyloidosis
Session: Transthyretin amyloidosis: long-term outcomes and emerging therapies (Rapid Fire Abstracts)
Monday, May 11, 16:45 – 17:45 CEST, 10:45 – 11:45 A.M. EST
Presenting Author: Vincent Algalarrondo, France

Influence of Disease-Modifying Therapy on the Effectiveness of Vutrisiran in Transthyretin Cardiac Amyloidosis
Session: Transthyretin amyloidosis: long-term outcomes and emerging therapies (Rapid Fire Abstracts)
Monday, May 11, 16:45 – 17:45 CEST, 10:45 – 11:45 A.M. EST
Presenting Author: Arielle Abovich, United States of America

Consistent Efficacy of Vutrisiran Across Sexes in ATTR-CM, HELIOS-B Trial –Prespecified Sex Analysis
Session: Transthyretin amyloidosis: long-term outcomes and emerging therapies (Rapid Fire Abstracts)
Monday, May 11, 16:45 – 17:45 CEST, 10:45 – 11:45 A.M. EST
Presenting Author: Josephine Mansell, United Kingdom

Comorbidity Burden in Transthyretin Amyloidosis With Cardiomyopathy: Insights From the HELIOS-B Trial
Session: Risk factors and comorbidities (Moderated ePosters 3)
Tuesday, May 12, 08:30 to 09:15 CEST, 2:30 – 3:15 A.M. EST
Presenting Author: Sarah Birkhoelzer, United Kingdom

AMVUTTRA^® (vutrisiran) INDICATIONS AND IMPORTANT SAFETY INFORMATION

Indications
In the EU, AMVUTTRA^® (vutrisiran) is indicated for the treatment of:

• hereditary transthyretin amyloidosis in adult patients with stage 1 or stage 2 polyneuropathy (hATTR-PN).
• wild-type or hereditary transthyretin amyloidosis in adult patients with cardiomyopathy (ATTR-CM).

Availability across the EU is subject to local reimbursement timelines.

Important Safety Information
Reduced Serum Vitamin A Levels and Recommended Supplementation
Vutrisiran treatment leads to a decrease in serum vitamin A levels. Supplementation of approximately, but not exceeding, 2500 IU to 3000 IU vitamin A per day is advised for patients taking vutrisiran. Patients should be referred to an ophthalmologist if they develop ocular symptoms suggestive of vitamin A deficiency (e.g., night blindness).

Adverse Reactions
Commonly reported adverse reactions with vutrisiran were injection site reactions and increase in blood alkaline phosphatase and alanine transaminase.

For additional information about vutrisiran, please see the full Summary of Product Characteristics.

About AMVUTTRA^® (vutrisiran)
AMVUTTRA^® (vutrisiran) is a transthyretin (TTR) silencer that delivers rapid knockdown of TTR at the source to address the underlying cause of transthyretin amyloidosis (ATTR). In a clinical study, AMVUTTRA rapidly knocked down TTR in as early as six weeks and decreased TTR levels by 87% with two and a half years of treatment. It is approved as a treatment for the polyneuropathy of hereditary transthyretin-mediated amyloidosis (hATTR-PN) in adults and for the cardiomyopathy of wild-type or hereditary transthyretin-mediated amyloidosis (ATTR-CM) in adults in various countries, globally. Administered quarterly via subcutaneous injection, AMVUTTRA is the first and only silencer approved for the treatment of ATTR-CM and hATTR-PN.

About Transthyretin Amyloidosis (ATTR)
Transthyretin amyloidosis (ATTR) is an underdiagnosed, rapidly progressive, debilitating, and fatal disease caused by pathogenic transthyretin (TTR) proteins, which accumulate as amyloid deposits in various parts of the body, including the nerves, heart, and gastrointestinal tract. Patients may present with polyneuropathy, cardiomyopathy, or both manifestations of disease. There are two different forms of ATTR – hereditary ATTR (hATTR), which is caused by a TTR gene variant, and wild-type ATTR (wtATTR), which occurs without a TTR gene variant. It is estimated that more than 500,000 people worldwide live with ATTR.

About RNAi
RNAi (RNA interference) is a natural cellular process of gene silencing that represents one of the most promising and rapidly advancing frontiers in biology and drug development today. Its discovery has been heralded as “a major scientific breakthrough that happens once every decade or so,” and was recognized with the award of the 2006 Nobel Prize for Physiology or Medicine. By harnessing the natural biological process of RNAi occurring in our cells, a new class of medicines known as RNAi therapeutics is now a reality. Small interfering RNA (siRNA), the molecules that mediate RNAi and comprise Alnylam’s RNAi therapeutic platform, function upstream of today’s medicines by potently silencing messenger RNA (mRNA) – the genetic precursors – that encode for disease-causing or disease pathway proteins, thus preventing them from being made. This is a revolutionary approach with the potential to transform the care of patients with genetic and other diseases.

About Alnylam Pharmaceuticals
Alnylam (Nasdaq: ALNY) is a leading global biopharmaceutical company and the pioneer of the RNA interference (RNAi) revolution. The Company is focused on developing transformative therapies with the potential to prevent, halt, or reverse disease. For more than two decades, Alnylam has advanced the Nobel-Prize-winning science of RNAi, delivering critical breakthroughs and six approved medicines. Alnylam has medicines available in more than 70 countries and a rapidly expanding and robust pipeline, in addition to consistently being recognized as an exceptional workplace and socially responsible organization. The Company is executing on its Alnylam 2030 strategy to accelerate innovation and scale impact to transform human health.

Alnylam Forward-Looking Statements
This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements other than historical statements of fact regarding Alnylam’s expectations, beliefs, goals, plans or prospects including, without limitation, statements regarding the potential for AMVUTTRA to be used as a first-line treatment for ATTR-CM; and Alnylam’s ability to execute on its Alnylam 2030 strategy to accelerate innovation and scale impact to transform human health, should be considered forward-looking statements. Actual results and future plans may differ materially from those indicated by these forward-looking statements as a result of various important risks, uncertainties and other factors, including, without limitation, risks and uncertainties relating to: Alnylam’s ability to successfully execute on its “Alnylam 2030” strategy; Alnylam’s ability to successfully launch, market and sell Alnylam’s approved products globally, including AMVUTTRA; Alnylam’s ability to discover and develop novel drug candidates and delivery approaches and successfully demonstrate the efficacy and safety of its product candidates; the pre-clinical and clinical results for Alnylam’s product candidates; actions or advice of regulatory agencies and Alnylam’s ability to obtain and maintain regulatory approval for its product candidates, as well as favorable pricing and reimbursement; delays, interruptions or failures in the manufacture and supply of Alnylam’s marketed products or its product candidates; obtaining, maintaining and protecting intellectual property; Alnylam’s ability to manage its growth and operating expenses through disciplined investment in operations; Alnylam’s ability to maintain strategic business collaborations; Alnylam’s dependence on third parties for the development and commercialization of certain products; the outcome of litigation and government investigations; the risk of future litigation and government investigations; and unexpected expenditures; as well as those risks and uncertainties more fully discussed in the “Risk Factors” filed with Alnylam’s 2025 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC), as may be updated from time to time in Alnylam’s subsequent Quarterly Reports on Form 10-Q, and in other filings that Alnylam makes with the SEC. In addition, any forward-looking statements represent Alnylam’s views only as of today and should not be relied upon as representing its views as of any subsequent date. Alnylam explicitly disclaims any obligation, except to the extent required by law, to update any forward-looking statements.

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