Alnylam Scientists Present New Data on RNAi Therapeutics at American Chemical Society (ACS) 2010 National Meeting

Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today that it will make a total of 16 oral presentations at the American Chemical Society (ACS) Fall 2010 240^th National Meeting & Exposition being held in Boston, Mass. from August 22-26, 2010. The main theme of this meeting is "Chemistry for Combating and Preventing Disease,” and the presentations are being made at the Oligonucleotide Therapeutics Symposium organized by the Carbohydrate Division of ACS. Data being presented by Alnylam scientists at this meeting include new results on design, synthesis, and characterization of siRNAs, siRNA conjugates, and delivery formulations.

"We are excited by the research being presented at this meeting, which together illustrate the very significant progress Alnylam scientists are making in the discovery and development of RNAi therapeutics. Certainly, these cumulative data demonstrate Alnylam’s continued scientific leadership in the advancement of RNAi therapeutics as a new class of innovative medicines,” said Muthiah Manoharan, Ph.D., Senior Vice President, Drug Discovery. "Some notable highlights from our presentations include results showing superior properties of canonical siRNAs compared with so-called ‘dicer substrate’ constructs, the application of ‘click chemistry’ approaches to the synthesis of siRNA conjugates, and the synthesis of novel cationic lipids for systemic delivery of siRNAs with lipid nanoparticles.”

The oral presentations being given at the conference by Alnylam scientists include an overview by Dr. Manoharan summarizing the progress made in improving and optimizing the chemistry utilized in the discovery of siRNAs, siRNA conjugates, and lipid-based formulations. Further, several of the presentations describe the design, synthesis, and analytical characterization of siRNAs with optimized properties, including:

• "Solid-phase synthesis of 5’-di- and tri-phosphates and their modified analogs of DNA, RNA and chemically modified oligonucleotides,” by Ivan Zlatev, Ph.D., Scientist;
• "Parallel high throughput synthesis of chemically modified 21-27mer siRNA sequences,” by Satya Kuchimanchi, Ph.D., Associate Director, Small Scale Synthesis;
• "Novel method for the confirmation of siRNA sequence by LC-MS/MS,” by Gary Lavine, Ph.D., Senior Scientist;
• "Evaluation of Canonical vs. Dicer-substrate siRNAs in vitro and in vivo,” by Don Foster, Senior Research Associate; and,
• "Modulation of thermal stability can enhance the potency of siRNA,” by Haripriya Addepalli, Research Associate.

Data are also being presented describing both lipid nanoparticle (LNP) and siRNA conjugation chemistry approaches for improved delivery of RNAi therapeutics including several new applications using "click chemistry” for the synthesis of novel materials:

• "Carbohydrate conjugation to siRNA for tissue-specific delivery,” by G. Rajeev Kallanthottathil, Ph.D., Director, Drug Discovery;
• "Efficient synthesis of siRNA-folic acid conjugates,” by Rajendra Pandey, Ph.D., Senior Scientist;
• "Synthesis and evaluation of bicyclic ketal-based cationic lipids for the delivery of siRNA via lipid nanoparticle delivery systems,” by Muthusamy Jayaraman, Ph.D., Principal Scientist;
• "Synthesis of oligo spermine-containing oligonucleotides for siRNA delivery,” by Shigeo Matsuda, Ph.D., Senior Scientist;
• "Conjugation strategies for RNAs using copper-catalyzed click chemistry,” by Chang Geng Peng, Ph.D., Scientist;
• "Non-nucleoside building blocks for copper-assisted and copper-free click chemistry for synthesis of oligonucleotide conjugates,” by K.N. Jayaprakash, Ph.D., Principal Scientist; and,
• "Solid-support immobilized, reusable Cu (I) catalyst for "click reactions” of oligonucleotides with ligands,” by Laxman Eltepu, Ph.D., Scientist.

In addition, several presentations will focus on the chemistry, manufacturing, and control of siRNAs, related to their development as RNAi therapeutic products:

• "Development of a stability-indicating, ion-pair RP-HPLC method for separation and quantitative determination of two siRNA duplexes in a liposome,” by Veeravagu Murugaiah, Ph.D., Principal Scientist;
• "Novel applications of aerosol-based detectors for the analysis of non-chromophore, multi-lipid, drug delivery vehicles,” by William Zedalis, Principal Research Associate; and,
• "Optimizing the LAL assay for detection of bacterial endotoxin in conjugated and formulated siRNAs,” by Mara Broberg, Research Associate.

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 applying its therapeutic expertise in RNAi to address significant medical needs, many of which cannot effectively be addressed with small molecules or antibodies, the current major classes of drugs. Alnylam is leading the translation of RNAi as a new class of innovative medicines with peer-reviewed research efforts published in the world’s top scientific journals including Nature, Nature Medicine, and Cell. The company is leveraging these capabilities to build a broad pipeline of RNAi therapeutics for the treatment of a wide range of disease areas, including respiratory syncytial virus (RSV), liver cancers, TTR-mediated amyloidosis (ATTR), hypercholesterolemia, and Huntington’s disease. In addition, Alnylam formed Alnylam Biotherapeutics, a division of the company focused on the development of RNAi technologies for application in manufacturing processes for biotherapeutic products, including recombinant proteins and monoclonal antibodies. The company’s leadership position in fundamental patents, technology, and know-how relating to RNAi has enabled it to form major alliances with leading companies including Medtronic, Novartis, Biogen Idec, Roche, Takeda, Kyowa Hakko Kirin, and Cubist. Alnylam and Isis are joint owners of Regulus Therapeutics Inc., a company focused on the discovery, development, and commercialization of microRNA therapeutics. Founded in 2002, Alnylam maintains headquarters in Cambridge, Massachusetts. For more information, please visit www.alnylam.com.

Alnylam Forward-Looking Statement

Various statements in this release concerning Alnylam’s future expectations, plans and prospects, including without limitation, its expectations regarding the development of effective and efficient delivery approaches for RNAi therapeutics, 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 Alnylam’s ability to continue advancing its delivery efforts, discover and develop novel drug candidates, and successfully demonstrate efficacy and safety of its drug candidates in human clinical trials, 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.