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

Alnylam Pharmaceuticals, Inc.

, 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.