Alnylam Initiates Phase 1 Open Label Extension (OLE) Study with ALN-AT3, an Investigational RNAi Therapeutic for the Treatment of Hemophilia and Rare Bleeding Disorders

– Provides Opportunity for People with Hemophilia who Participated in Phase 1 Trial to Receive ALN-AT3 on Ongoing Basis –

– Pivotal Studies on Track to Begin in Mid-2016 –

CAMBRIDGE, Mass.--()--Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today that it has initiated a Phase 1 open-label extension (OLE) study with ALN-AT3, a subcutaneously administered, investigational RNAi therapeutic targeting antithrombin (AT) for the treatment of hemophilia and rare bleeding disorders. The Phase 1 OLE study will evaluate the long-term safety and efficacy of ALN-AT3 and provide people with hemophilia enrolled in the Phase 1 study the opportunity for continued dosing. The company plans to report clinical data from the Phase 1 OLE study at least once per year, beginning in 2016.

“This Phase 1 OLE study brings us one step closer to our goal of providing a safe, subcutaneously administered, long-acting option for hemostasis management to people with hemophilia and other rare bleeding disorders. The initiation of this study marks our continued progress with ALN-AT3, and we are pleased to provide hemophilia patients in our Phase 1 trial the opportunity to receive this investigational medicine on an ongoing basis,” said Akshay Vaishnaw, M.D., Ph.D., Executive Vice President of R&D and Chief Medical Officer at Alnylam. “We believe the ALN-AT3 data presented to date have been very promising, demonstrating potent, dose-dependent, and durable knockdown of AT with the potential to re-balance hemostasis in people with severe hemophilia through normalization of thrombin generation. We look forward to providing continued clinical updates, including results for once-monthly subcutaneous dosing in hemophilia patients, later this year.”

The AT3 Phase 1 OLE study is an open-label, multi-center study designed to evaluate the long-term safety and tolerability of ALN-AT3 in hemophilia patients who were previously enrolled in the Phase 1 study. Eligible patients treated in the Phase 1 study can enroll in the OLE study, where they will receive ALN-AT3 for up to the earlier of two years or until the drug receives regulatory approval and becomes commercially available in their market. In addition to evaluating the long-term safety and efficacy of ALN-AT3 in hemophilia patients, the study will evaluate clinical activity of ALN-AT3, as measured by knockdown of serum AT, increases in thrombin generation, and reduction in the frequency of bleeding events.

Genzyme Alliance

In January 2014, Alnylam and Genzyme, a Sanofi company, formed an alliance to accelerate and expand the development and commercialization of RNAi therapeutics across the world. The alliance is structured as a multi-product geographic alliance in the field of rare diseases. Alnylam retains product rights in North America and Western Europe, while Genzyme obtained the right to access certain programs in Alnylam's current and future Genetic Medicines pipeline in the rest of the world (ROW) through the end of 2019, together with certain broader co-development/co-commercialization rights and global rights for certain products. In the case of ALN-AT3, Genzyme has elected to opt into the program for its rest-of-world rights, while retaining their further opt-in right to co-develop and co-promote ALN-AT3 with Alnylam in North America and Western Europe, subject to certain restrictions.

About Hemophilia and Rare Bleeding Disorders

Hemophilias are hereditary disorders caused by genetic deficiencies of various blood clotting factors, resulting in recurrent bleeds into joints, muscles, and other major internal organs. Hemophilia A is defined by loss-of-function mutations in Factor VIII, and there are greater than 40,000 registered persons in the U.S. and E.U. with Hemophilia A. Hemophilia B, defined by loss-of-function mutations in Factor IX, affects greater than 9,500 registered persons in the U.S. and E.U. Other Rare Bleeding Disorders (RBD) are defined by congenital deficiencies of other blood coagulation factors, including Factors II, V, VII, X, and XI, and there are about 1,000 persons worldwide with a severe bleeding phenotype. Standard treatment for persons living with hemophilia involves replacement of the missing clotting factor either as prophylaxis or on-demand therapy. However, as many as one third of people with severe hemophilia A will develop an antibody to their replacement factor - a very serious complication; persons in this ‘inhibitor' subset become refractory to standard replacement therapy. There exists a small subset of persons living with hemophilia who have co-inherited a prothrombotic mutation, such as Factor V Leiden, antithrombin deficiency, protein C deficiency, and prothrombin G20210A. People who have co-inherited these prothrombotic mutations are characterized as having a later onset of disease, lower risk of bleeding, and reduced requirements for Factor VIII or Factor IX treatment as part of their disease management. There exists a significant need for novel therapeutics to treat people living with hemophilia.

About Antithrombin (AT)

Antithrombin (AT, also known as "antithrombin III" and "SERPINC1") is a liver expressed plasma protein and member of the "serpin" family of proteins that acts as an important endogenous anticoagulant by inactivating Factor Xa and thrombin. AT plays a key role in normal hemostasis, which has evolved to balance the need to control blood loss through clotting with the need to prevent pathologic thrombosis through anticoagulation. In hemophilia, the loss of certain procoagulant factors (Factor VIII and Factor IX, in the case of hemophilia A and B, respectively) results in an imbalance of the hemostatic system toward a bleeding phenotype. In contrast, in thrombophilia (e.g., Factor V Leiden, protein C deficiency, antithrombin deficiency, amongst others), certain mutations result in an imbalance in the hemostatic system toward a thrombotic phenotype. Since co-inheritance of prothrombotic mutations may ameliorate the clinical phenotype in hemophilia, inhibition of AT defines a novel strategy for improving hemostasis.

About GalNAc Conjugates and Enhanced Stabilization Chemistry (ESC)-GalNAc Conjugates

GalNAc-siRNA conjugates are a proprietary Alnylam delivery platform and are designed to achieve targeted delivery of RNAi therapeutics to hepatocytes through uptake by the asialoglycoprotein receptor. Alnylam's Enhanced Stabilization Chemistry (ESC)-GalNAc-conjugate technology enables subcutaneous dosing with increased potency and durability, and a wide therapeutic index. This delivery platform is being employed in nearly all of Alnylam's pipeline programs, including programs in clinical development.

About 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 RNA (siRNA), 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. Alnylam’s pipeline of investigational RNAi therapeutics is focused in 3 Strategic Therapeutic Areas (STArs): Genetic Medicines, with a broad pipeline of RNAi therapeutics for the treatment of rare diseases; Cardio-Metabolic Disease, with a pipeline of RNAi therapeutics toward genetically validated, liver-expressed disease targets for unmet needs in cardiovascular and metabolic diseases; and Hepatic Infectious Disease, with a pipeline of RNAi therapeutics that address the major global health challenges of hepatic infectious diseases. In early 2015, Alnylam launched its “Alnylam 2020” guidance for the advancement and commercialization of RNAi therapeutics as a whole new class of innovative medicines. Specifically, by the end of 2020, Alnylam expects to achieve a company profile with 3 marketed products, 10 RNAi therapeutic clinical programs – including 4 in late stages of development – across its 3 STArs. The company’s demonstrated commitment to RNAi therapeutics has enabled it to form major alliances with leading companies including Merck, Medtronic, Novartis, Biogen, Roche, Takeda, Kyowa Hakko Kirin, Cubist, GlaxoSmithKline, Ascletis, Monsanto, The Medicines Company, and Genzyme, a Sanofi company. In addition, Alnylam holds an equity position in Regulus Therapeutics Inc., a company focused on discovery, development, and commercialization of microRNA therapeutics. Alnylam scientists and collaborators have published their research on RNAi therapeutics in over 200 peer-reviewed papers, including many in the world’s top scientific journals such as Nature, Nature Medicine, Nature Biotechnology, Cell, New England Journal of Medicine, and The Lancet. Founded in 2002, Alnylam maintains headquarters in Cambridge, Massachusetts. For more information about Alnylam’s pipeline of investigational RNAi therapeutics, 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, Alnylam's views with respect to the potential for RNAi therapeutics, including ALN-AT3 for the treatment of hemophilia and rare bleeding disorders. , expectations regarding the reporting of data from clinical studies, in particular the Phase 1 OLE study for ALN-AT3, expectations regarding its STAr pipeline growth strategy, and its plans regarding commercialization of RNAi therapeutics, including ALN-AT3, 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, the pre-clinical and clinical results for its product candidates, which may not be replicated or continue to occur in other subjects or in additional studies or otherwise 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, 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 manage operating expenses, 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 development, manufacture, marketing, sales and distribution of products, the outcome of litigation, and unexpected expenditures, as well as those risks more fully discussed in the "Risk Factors" filed with Alnylam's most recent Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (SEC) and in other filings that Alnylam makes with the SEC. 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 explicitly disclaims any obligation to update any forward-looking statements.

Contacts

Alnylam Pharmaceuticals, Inc.
Michael Mason, 617-551-8327
Vice President, Finance and Treasurer
or
Spectrum
Liz Bryan (Media), 202-955-6222 x2526

Contacts

Alnylam Pharmaceuticals, Inc.
Michael Mason, 617-551-8327
Vice President, Finance and Treasurer
or
Spectrum
Liz Bryan (Media), 202-955-6222 x2526