Alnylam Receives New Issued U.S. Patent Broadly Covering Small Interfering RNAs and Strengthens Leadership in Intellectual Property for RNAi Therapeutics.

CAMBRIDGE, Mass. -- New Tuschl II '196 Patent Covers Methods of Making Small Interfering RNAs With and Without Chemical Modifications

Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today that a new key fundamental patent from its exclusively held "Tuschl II" patent series was issued by the United States Patent and Trademark Office (USPTO). The newly issued U.S. patent (U.S. Patent No. 7,078,196 or " '196 patent") broadly covers methods of making small interfering RNAs (siRNAs), the molecules that mediate RNAi, and includes 79 claims covering chemical modifications needed to introduce "drug-like" properties in RNAi therapeutics. The issued patent is exclusively licensed to Alnylam for RNAi therapeutics on a worldwide basis through an agreement with Garching Innovation GmbH, the licensing agent for the Max Planck Society. The '196 patent further strengthens Alnylam's intellectual property (IP) leadership that includes another Tuschl II patent (U.S. Patent No. 7,056,704 or " '704 patent"), covering methods of making siRNAs to target any messenger RNA in a mammalian cell, and the recent successful outcome of the European Opposition Proceedings for the Kreutzer-Limmer I patent (EP 1144623 or " '623 patent"), where amended patent claims covering siRNAs with 15-21 base pairs were upheld.

"We are gratified that the USPTO has acknowledged the key inventions of Professor Thomas Tuschl performed at the Max Planck Institute in Gottingen," said Professor Peter Gruss, President of the Max Planck Society. "This critical patent for RNAi therapeutics is owned by the Max Planck Society and has been licensed exclusively to Alnylam for commercialization. We are impressed with the progress Alnylam is making in its effort to develop innovative medicines using one of our Institute's most important scientific discoveries."

The new '196 patent is part of the groundbreaking research published in 2001 in the journal Nature by Thomas Tuschl, Ph.D., a founder of Alnylam. In this seminal work performed at Max Planck, Professor Tuschl and his colleagues provided the first peer-reviewed published evidence that RNAi is mediated by small double-stranded RNAs with defined structural features and that synthetic siRNAs, with or without chemical modification, can be used to achieve RNAi in mammalian cells.

"This new patent extends what we believe is an unparalleled IP estate for RNAi therapeutics that includes over 150 patents issued in the world's largest pharmaceutical markets," said John Maraganore, Ph.D., President and Chief Executive Officer of Alnylam Pharmaceuticals. "The '196 patent, together with other Alnylam-held IP assets, strengthens our continued efforts to create value through partnerships and license agreements with major pharmaceutical companies, biotechnology companies, and research product suppliers. Indeed, the unmatched strength of our patent estate supports a track record of business execution with over 20 current partners and licensees that have provided in excess of $100 million in funding to date, and a source of committed and sustainable funding for the future. Strategically, this important funding source for Alnylam supports our efforts to bring RNAi therapeutics to the market in a capital-efficient manner."

The 79 claims for the '196 patent cover the preparation of double-stranded RNAs having key structural elements that are widely recognized as critical requirements for the therapeutic activity of siRNAs, including:

--A double stranded region formed from two RNA strands of a length of 19-25 nucleotides; and,

--One or more 3'-overhangs at the ends of the double-stranded molecule.

The claims cover siRNAs with or without chemical modifications that are used to introduce certain drug-like properties into siRNAs such as stability and delivery. The claims cover broad forms of such chemical modifications, including those of the 2' hydroxy position of the ribose backbone used to generate so-called "no-ribose" or "siNA" forms of RNAi therapeutics. These chemical modifications include the use of phosphorothioate backbone linkages or 2'-0-methyl, and/or 2'-fluoro chemistries, irrespective of the percent of nucleotides modified and the extent of such modifications.

The new issued claims for U.S. Patent No. 7,078,196 will be made accessible on the Alnylam website at: www.alnylam.com/patent-estate.

"It should become increasingly clear as patents issue in the field that Alnylam has assembled exclusive ownership of and access to critical IP needed for the development of RNAi drugs," said Robert Millman, Chief Intellectual Property Counsel of Alnylam. "Because of the enablement and early priority date for the '196 patent, it is widely cited by patent offices across the world as prior art against later filed patent applications claiming chemically modified siRNAs."

In addition to the newly issued Tuschl II patent (U.S. Patent No. 7,078,196), Alnylam's IP estate includes issued or granted fundamental patents in the world's major pharmaceutical markets that claim the broad structural and functional properties of synthetic RNAi therapeutic products. As it applies to the U.S. and EU alone, these include:

--The Tuschl II '704 patent (U.S. Patent No. 7,056,704) issued in June 2006, which broadly covers methods of making siRNAs to silence any and all disease targets;

--The Kreutzer-Limmer I '623 patent (EP 1144623) granted in August 2002, and upheld in June 2006, covering methods, medicaments, and uses of siRNAs having, among other structural features, a length of 15-21 base pairs;

--The Kreutzer-Limmer I '945 patent (EP 1214945) granted in June 2005, covering compositions, methods, and uses of siRNAs with a length between 15 and 49 nucleotides;

--The Kreutzer-Limmer II '061 patent (EP 1352061) granted in May 2006, covering compositions, methods, and uses of certain siRNAs and derivatives directed toward over 125 disease targets;

--Additional fundamental patents and patent applications licensed to Alnylam on an exclusive or non-exclusive basis include those of Crooke (U.S. Patent Nos. 5,898,031 and 6,107,094), Fire and Mello (U.S. Patent No. 6,506,559), and Glover et al. (EP 1230375); and,

--Several divisional patent applications pending of the aforementioned issued or granted patents and additional patent applications pending including Tuschl I.

In addition, Alnylam has a broad worldwide license for RNAi therapeutics from Isis Pharmaceuticals, Inc. for more than 150 issued patents pertaining to specific chemical modification of oligonucleotides used to introduce drug-like properties in siRNAs. These include:

--Phosphorothioate and 2'-O-methyl modifications (Buhr, U.S. Patent No. 6,473,205); and,

--2'-Fluoro modifications (Cook, U.S. Patent Nos. 5,670,633; 6,005,087; and 6,531,584).

In addition to claims issued in '196 patent, Alnylam invites interested licensees to view issued or granted claims for other key Alnylam patents at www.alnylam.com/patent-estate.

About RNA Interference (RNAi)

RNA interference, or RNAi, is a naturally occurring mechanism within cells for selectively silencing and regulating specific genes. Since many diseases are caused by the inappropriate activity of specific genes, the ability to silence genes selectively through RNAi could provide a new way to treat a wide range of human diseases. RNAi is induced by small, double-stranded RNA molecules. One method to activate RNAi is with chemically synthesized small interfering RNAs, or siRNAs, which are double-stranded RNAs that are targeted to a specific disease-associated gene. The siRNA molecules are used by the natural RNAi machinery in cells to cause highly targeted gene silencing.

About Alnylam

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 building a pipeline of RNAi therapeutics; its lead program is in Phase I human clinical trials for the treatment of respiratory syncytial virus (RSV) infection, which is the leading cause of hospitalization in infants in the U.S. 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 Merck, Medtronic, and Novartis. The company, founded in 2002, maintains global headquarters in Cambridge, Massachusetts, and has an additional operating unit in Kulmbach, Germany. Alnylam is honored to be the "emerging/mid-cap" company recipient of the 2006 James D. Watson Helix Award, the biotechnology industry's award for outstanding achievement. For more information, visit www.alnylam.com.

About Max Planck Society / Garching Innovation

Founded in 1948 as successor of the Kaiser Wilhelm Society, the Max Planck Society for the Advancement of Science (MPS) is an independent, non-profit scientific research organization. The MPS maintains about 80 research institutes, the majority of which are in Germany. The research institutes focus on natural sciences, life sciences, social sciences, and the humanities. The Max Planck Society is particularly active in new and innovative research areas that are outside the scope of German universities. The Max Planck Society has produced 16 Nobel laureates since its foundation. Garching Innovation GmbH, a wholly-owned subsidiary of Max Planck Society, acts as its technology transfer agency. Garching Innovation is responsible for the commercialization of intellectual property created within the research institutes of Max Planck Society by granting licenses to the industry and supporting the formation of start ups from MPS. For more information please visit http://www.mpg.de/ and http://www.garching-innovation.de.

Alnylam Forward-Looking Statements

Various statements in this release concerning our future expectations, plans and prospects, including our views with respect to the timing and the future issuance of patents and the importance and scope of our intellectual property rights and the development of 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 risks related to: our approach to discover and develop novel drugs, which is unproven and may never lead to marketable products; obtaining, maintaining and protecting intellectual property utilized by our products; our ability to enforce our patents against infringers and to defend our patent portfolio against challenges from third parties; our ability to obtain additional funding to support our business activities; our dependence on third parties for development, manufacture, marketing, sales and distribution of products; the successful development of our product candidates, all of which are in early stages of development; obtaining regulatory approval for products; competition from others using technology similar to ours and others developing products for similar uses; our dependence on collaborators; and our short operating history; as well as those risks more fully discussed in the "Risk Factors" section of our most recent quarterly report on Form 10-Q on file with the Securities and Exchange Commission. In addition, any forward-looking statements represent our views only as of today and should not be relied upon as representing our views as of any subsequent date. We do not assume any obligation to update any forward-looking statements.