Alnylam Collaborator Regeneron Advances CIDEBsiRNA with Promising First-in-Human Results in Patients with MASLD

Alnylam is eligible for development milestones and tiered, double-digit royalties up to 20% on the Regeneron-led candidate.

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Single administration of CIDEB^siRNA resulted in rapid, deep and durable reductions in liver fat by up to 80% that were sustained through 36 weeks

Data shared in oral presentation at AASLD The Liver Meeting^® and simultaneously published in The New England Journal of Medicine

Results demonstrate how Alnylam's RNAi platform and strategic partnerships can expand therapeutic opportunities and create long-term value beyond its wholly owned pipeline

CAMBRIDGE, Mass.--(BUSINESS WIRE)-- Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), the leading RNAi therapeutics company, today announced that its collaborator, Regeneron Pharmaceuticals, Inc. shared initial results from a first-in-human trial that demonstrated a single subcutaneous dose of CIDEB^siRNA (previously known as ALN-CIDEB) rapidly normalized liver fat and improved liver injury markers in patients with metabolic-dysfunction-associated steatotic liver disease (MASLD) with effects that were sustained through week 36. The Regeneron data were published by The New England Journal of Medicine and simultaneously presented in an oral session at the American Association for the Study of Liver Diseases (AASLD) The Liver Meeting^® 2026.

CIDEB^siRNA is an investigational RNAi therapeutic (also known as an siRNA therapeutic). Scientists at the Regeneron Genetics Center^® (RGC) analyzed genetic data to discover and/or validate genetic variants in the CIDEB and other genes that are associated with liver disease risk. Building on these findings, Regeneron collaborated with Alnylam to generate an siRNA targeting CIDEB. Since 2023 when the candidate was identified, Regeneron has led development and holds exclusive rights for commercialization of CIDEB^siRNA. Alnylam is eligible to receive development milestones and tiered, double-digit royalties up to 20%.

“The magnitude and durability of the reductions in liver fat observed with CIDEB^siRNA following a single administration are particularly encouraging and represent an important early signal for the potential of RNAi in treating metabolic liver disease,” said Pushkal Garg, M.D., Chief Research and Development Officer at Alnylam. “These findings reinforce our conviction that RNAi therapeutics can address a much broader range of diseases than those we treat today. They also demonstrate the value of our partnership model, which allows promising science to advance into new disease areas, reach more patients and create additional opportunities for long-term value.”

Regeneron’s ongoing Phase 1/2 randomized, double-blind, placebo-controlled trial is evaluating the safety and tolerability of CIDEB^siRNA in adult participants with MASLD and metabolic dysfunction-associated steatohepatitis (MASH). The primary goal of the trial is to evaluate safety and tolerability with efficacy evaluated as a secondary endpoint through measures such as change in liver fat fraction by magnetic resonance imaging-proton density fat fraction (MRI-PDFF).

About RNAi
RNAi (RNA interference) is a natural cellular process of gene silencing that has become an important and clinically validated platform for drug development. Its discovery was recognized with the award of the 2006 Nobel Prize for Physiology or Medicine. By harnessing RNAi, Alnylam pioneered a new class of medicines known as RNAi therapeutics. Small interfering RNA (siRNA), the molecules that mediate RNAi and comprise Alnylam’s 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. RNAi therapeutics have been used to treat hundreds of thousands of patients worldwide, demonstrating the impact of this approach across rare and common 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. For more information, please visit www.alnylam.com or follow Alnylam on X, LinkedIn, Facebook, Instagram, or YouTube.

Forward-Looking Statements
This press release contains forward-looking statements. Forward-looking statements include statements regarding Alnylam’s expectations, beliefs, goals, plans or prospects, including, without limitation, statements regarding: the potential efficacy or safety of CIDEB^siRNA for the treatment of MASLD or any other indication; the potential for Alnylam to receive milestones or royalties on account of the development and/or commercialization of CIDEB^siRNA; the potential for RNAi to treat metabolic liver disease and to address a much broader range of diseases than those treated today; the potential for Alnylam’s partnership model to allow Alnylam to allow promising science to advance into new disease areas, reach more patients and create additional opportunities for long-term value; and Alnylam’s ability to achieve the goals in its Alnylam 2030 strategy. 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; 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 most recent periodic report (Quarterly Report on Form 10-Q or Annual Report on Form 10-K) filed with the SEC and in its other SEC filings. Alnylam explicitly disclaims any obligation, except to the extent required by law, to update any forward-looking statements.

View source version on businesswire.com: https://www.businesswire.com/news/home/20261110694883/en/

Alyssa Kneller
(Media)
media@alnylam.com

Josh Brodsky
(Investors)
investors@alnylam.com

Source: Alnylam Pharmaceuticals, Inc.

Key Terms

masld medical

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a chronic condition where excess fat builds up in the liver due to underlying metabolic problems like insulin resistance, obesity, or high blood lipids. Think of the liver like a kitchen filter getting clogged with grease; over time that buildup can reduce function and lead to inflammation or scarring, which matters to investors because it signals a large, growing market for diagnostics, treatments, and related medical services.

sirna technical

Small interfering RNA (siRNA) is a short strand of genetic material that binds to and destroys the messenger RNA that carries instructions for making a specific protein, effectively switching that gene off. Investors care because siRNA is a platform for precise medicines: successful trials or approvals can create high-value drugs, while delivery challenges, manufacturing complexity, patent positions and regulatory risk can sharply affect a biotech company's prospects.

rnai technical

RNAi, short for RNA interference, is a natural cellular process that acts like a mute button for specific genes by using small RNA molecules to stop a target gene from producing its protein. For investors, RNAi matters because it is the underlying mechanism behind a class of precision medicines that can silence disease-causing genes, offering high potential returns but also scientific, regulatory and manufacturing risks unique to novel drug platforms.

mri-pdff medical

MRI-PDFF (Magnetic Resonance Imaging-Proton Density Fat Fraction) is a medical imaging technique that measures the amount of fat within the liver or other tissues. For investors, it provides a precise way to assess health risks related to fat buildup, which can impact healthcare costs and the valuation of related companies. Its accuracy helps in monitoring treatment progress and predicting potential medical expenses, making it relevant for healthcare decision-making and investment considerations.