August 6, 2008

Alnylam Awarded Continued Funding Under U.S. Government Contract to Develop RNAi Therapeutics for Biological Threats

Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, today announced that the National Institute of Allergy and Infectious Diseases (NIAID), a component of the National Institutes of Health (NIH), has committed to $7.5 million of continued funding related to the 2006 contract for the development of a broad spectrum RNAi anti-viral therapeutic against hemorrhagic fever virus, including Ebola virus. Ebola virus can cause a severe, often fatal infection, and poses a potential biological safety risk and bioterrorism threat.

"We are pleased with the continued support of the federal government for the development of an anti-viral RNAi therapeutic for Ebola," said Barry Greene, President and Chief Operating Officer. "To date, we have been granted more than $63 million in federal contracts for Alnylam Biodefense, and we are looking forward to continuing our work with the NIH to help strengthen our nation's capabilities to counter serious biological security threats."

"We are encouraged by the data we have seen with the Ebola program. These data have demonstrated potent and specific in vivo efficacy mediated by an RNAi mechanism," said Antonin de Fougerolles, Ph.D., Senior Director of Research at Alnylam. "This funding from the NIAID allows us to continue to develop our technology as we advance our pipeline programs."

In September 2006, Alnylam was awarded a federal contract (No. HHSN266200600012C) providing the company with up to $23 million in funding over a four-year period to develop small interfering RNAs (siRNAs), the molecules that mediate RNAi, as anti-viral drugs targeting Ebola virus. To date, the government has committed to paying Alnylam up to $14.2 million for the first two years of the contract. As a result of the continued progress of this program, the government has committed to fund an additional $7.5 million over year three of the contract.

At the RNAi Keystone Symposia in March 2008, Alnylam presented pre-clinical data from this program utilizing an optimized RNAi therapeutic formulated in a lipid particle for systemic delivery. These data showed that potent siRNAs with in vitro anti-viral activity were identified against all genes in the Ebola genome. A greater than 95 percent decrease in viral titer was seen when an RNAi therapeutic targeting one of these genes, VP35, was administered to mice infected with Ebola. Moreover, the VP35 siRNA, as compared with a control non-specific siRNA, protected both mice and guinea pigs from lethal Ebola infection. This work was done in collaboration with Tekmira Pharmaceuticals Corporation using their lipid particle delivery formulation technology.

As part of a public sector-private sector partnership with its Ebola program, Alnylam is working with the United States Army Medical Research Institute of Infectious Diseases (USAMRIID), an organization which is uniquely experienced in the handling, safety, and security requirements of specialized biological agents. Alnylam produces drug candidates which are then sent to USAMRIID for in vitro and in vivo testing against Ebola virus.

About Alnylam BioDefense(TM)

Alnylam Biodefense was established to build a robust platform for developing RNAi therapeutics targeting threats of bioterrorism. Funding for the company's Ebola virus, pandemic flu, and viral hemorrhagic fever programs represents an example of broad public health and federal interest in the potential of RNAi technology to treat and prevent disease from these, and other serious and life-threatening viruses. Government funding extends Alnylam's anti-viral pipeline, which includes programs for treatment of: respiratory syncytial virus (RSV) infection with ALN-RSV01, which is in Phase II human clinical trials; pandemic influenza with ALN-FLU01 in a partnership with Novartis; and JC virus in a partnership with Biogen Idec.

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. RNAi therapeutics target the cause of diseases by potently silencing specific messenger RNAs (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; its most advanced program is in Phase II human clinical trials for the treatment of respiratory syncytial virus (RSV) infection. In addition, the company is developing RNAi therapeutics for the treatment of a wide range of disease areas, including hypercholesterolemia, liver cancers, and Huntington's disease. 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, and Kyowa Hakko. To reflect its outlook for key scientific, clinical, and business initiatives, Alnylam has established "RNAi 2010" which includes the company's plan to significantly expand the scope of delivery solutions for RNAi therapeutics, have four or more programs in clinical development, and to form four or more new major business collaborations, all by the end of 2010. Alnylam is a joint owner of Regulus Therapeutics LLC, a joint venture focused on the discovery, development, and commercialization of microRNA therapeutics. Founded in 2002, Alnylam maintains headquarters in Cambridge, Massachusetts. For more information, visit

Alnylam Forward-Looking Statements

Various statements in this release concerning Alnylam's future expectations, plans and prospects, including without limitation our plans with respect to the discovery and development of an RNAi therapeutic for Ebola virus, 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 risks related to: Alnylam's approach to discover and develop novel drugs, which is unproven and may never lead to marketable products; obtaining, maintaining and protecting intellectual property; Alnylam's ability to enforce its patents against infringers and to defend its patent portfolio against challenges from third parties; Alnylam's ability to obtain additional funding to support its business activities, including but not limited to additional funding under government contracts; Alnylam's dependence on third parties for development, manufacture, marketing, sales and distribution of products; obtaining regulatory approval for products; competition from others using technology similar to Alnylam's and others developing products for similar uses; Alnylam's dependence on collaborators; and Alnylam's short operating history; as well as those risks more fully discussed in the "Risk Factors" section of its most recent annual 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.