Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today that the United States Patent and Trademark Office (USPTO) has issued a Notice of Allowance for patent application number 12/813,448, covering the company's proprietary second generation lipid nanoparticle (LNP) platform, including the "MC3" lipid. This second generation LNP delivery platform is being utilized in development programs as part of the company's "Alnylam 5x15?" product strategy including: ALN-TTR02, an RNAi therapeutic targeting transthyretin (TTR) for the treatment of transthyretin-mediated amyloidosis (ATTR); ALN-PCS, an RNAi therapeutic targeting PCSK9 for the treatment of severe hypercholesterolemia; and potentially other programs.

"We are very pleased with the USPTO's allowance of claims for this important patent related to our second generation LNPs, thus acknowledging the novelty of the MC3 lipid for systemic delivery of RNAi therapeutics," said Laurence Reid, Ph.D., Senior Vice President and Chief Business Officer of Alnylam. "Importantly, these novel LNPs exhibit significant improvements in potency and therapeutic index for RNAi therapeutics, as evidenced by our recent human data with ALN-PCS, and also define Alnylam's LNP platform for advancement of ALN-TTR02 and potentially other 'Alnylam 5x15' programs."

The newly allowed patent application includes 30 claims covering composition of matter and formulations of MC3, as well as methods of using these compositions and formulations. The patent application lists as inventors Jianxin Chen and Steven Ansell of AlCana Technologies, Inc., and Akin Akinc, Joseph Robert Dorkin, Xiaojun Qin, William Cantley, Muthiah Manoharan, Kallanthottathil G. Rajeev, Jayaprakash K. Narayannair and Muthusamy Jayaraman of Alnylam.

About RNA Interference (RNAi)

RNAi (RNA interference) is a revolution in biology, representing a breakthrough in understanding how genes are turned on and off in cells, and a completely new approach to drug discovery and development. Its discovery has been heralded as "a major scientific breakthrough that happens once every decade or so," and represents one of the most promising and rapidly advancing frontiers in biology and drug discovery today which was awarded the 2006 Nobel Prize for Physiology or Medicine. RNAi is a natural process of gene silencing that occurs in organisms ranging from plants to mammals. By harnessing the natural biological process of RNAi occurring in our cells, the creation of a major new class of medicines, known as RNAi therapeutics, is on the horizon. Small interfering RNAs (siRNAs), the molecules that mediate RNAi and comprise Alnylam's RNAi therapeutic platform, target the cause of diseases by potently silencing specific mRNAs, thereby preventing disease-causing proteins from being made. RNAi therapeutics have the potential to treat disease and help patients in a fundamentally new way.

About Alnylam Pharmaceuticals

Alnylam is a biopharmaceutical company developing novel therapeutics based on RNA interference, or RNAi. The company is leading the translation of RNAi as a new class of innovative medicines with a core focus on RNAi therapeutics for the treatment of genetically defined diseases, including ALN-TTR for the treatment of transthyretin-mediated amyloidosis (ATTR), ALN-PCS for the treatment of severe hypercholesterolemia, ALN-HPN for the treatment of refractory anemia, ALN-APC for the treatment of hemophilia, and ALN-TMP for the treatment of hemoglobinopathies. As part of its "Alnylam 5x15TM" strategy, the company expects to have five RNAi therapeutic products for genetically defined diseases in clinical development, including programs in advanced stages, on its own or with a partner by the end of 2015. Alnylam has additional partner-based programs in clinical or development stages, including ALN-RSV01 for the treatment of respiratory syncytial virus (RSV) infection, ALN-VSP for the treatment of liver cancers, and ALN-HTT for the treatment of Huntington's disease. The company's leadership position on RNAi therapeutics and intellectual property have enabled it to form major alliances with leading companies including Merck, Medtronic, Novartis, Biogen Idec, Roche, Takeda, Kyowa Hakko Kirin, and Cubist. In addition, Alnylam and Isis co-founded Regulus Therapeutics Inc., a company focused on discovery, development, and commercialization of microRNA therapeutics; Regulus has formed partnerships with GlaxoSmithKline and Sanofi. Alnylam has also formed Alnylam Biotherapeutics, a division of the company focused on the development of RNAi technologies for applications in biologics manufacturing, including recombinant proteins and monoclonal antibodies. Alnylam's VaxiRNA? platform applies RNAi technology to improve the manufacturing processes for vaccines; GlaxoSmithKline is a collaborator in this effort. Alnylam scientists and collaborators have published their research on RNAi therapeutics in over 100 peer-reviewed papers, including many in the world's top scientific journals such as Nature, Nature Medicine, Nature Biotechnology, and Cell. Founded in 2002, Alnylam maintains headquarters in Cambridge, Massachusetts. For more information, please visit www.alnylam.com.

Alnylam Forward-Looking Statements

Various statements in this release concerning Alnylam's future expectations, plans and prospects, including, without limitation, statements regarding Alnylam's expectations with respect to its second-generation LNP delivery platform and its "Alnylam 5x15" product strategy, constitute forward-looking statements for the purposes of the safe harbor provisions under The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including, without limitation, Alnylam's ability to discover and develop novel drug candidates and delivery approaches, successfully demonstrate the efficacy and safety of its drug candidates, including ALN-PCS and ALN-TTR02, the pre-clinical and clinical results for its product candidates, including ALN-PCS and ALN-TTR02, which may not support further development of product candidates, actions of regulatory agencies, which may affect the initiation, timing and progress of clinical trials, obtaining, maintaining and protecting intellectual property, Alnylam's ability to enforce its patents against infringers and defend its patent portfolio against challenges from third parties, including its patents covering MC3, obtaining regulatory approval for products, competition from others using technology similar to Alnylam's and others developing products for similar uses, Alnylam's ability to obtain additional funding to support its business activities and establish and maintain strategic business alliances and new business initiatives, Alnylam's dependence on third parties for access to intellectual property, and the development, manufacture, marketing, sales and distribution of products, and the outcome of litigation, as well as those risks more fully discussed in the "Risk Factors" section of its most recent quarterly report on Form 10-Q on file with the Securities and Exchange Commission. 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 does not assume any obligation to update any forward-looking statements.

Alnylam Pharmaceuticals, Inc.
Cynthia Clayton, 617-551-8207
Vice President, Investor Relations and
Corporate Communications
or
Spectrum
Amanda Sellers, 202-955-6222 x2597 (Media)