Biogen Idec Signs License Agreement with Amunix for XTENylated Factor VIII

– Amunix could receive up to $39 million in upfront and milestone payments –

Mountain View, CA – April 21, 2014 – Amunix Operating Inc. announced today that Biogen Idec (NASDAQ: BIIB) has exercised its option to enter into an exclusive, worldwide license agreement to research and develop novel, fully-recombinant Factor VIII products with improved therapeutic properties.  Under the terms of the option agreement, Amunix will receive an upfront $1 million payment and will also be eligible to receive up to $38 million in clinical and commercial milestone payments.  In addition, royalties will be paid on commercial sales by Biogen Idec for Factor VIII products incorporating Amunix proprietary XTEN technology.

In March 2011, Amunix and Biogen Idec initiated a Research and Option Agreement under which both companies would collaborate to combine Amunix’s expertise in protein half-life extension and its proprietary XTEN technology with Biogen Idec’s expertise in both hemophilia and engineering long-lasting coagulation factors.  Under the license agreement announced today, Biogen Idec triggered its option for XTENylated Factor VIII products. Biogen Idec will be responsible for developing, manufacturing and commercializing therapeutic product candidates resulting from the collaboration.

“We are pleased to be working with Biogen Idec as our partner, and their decision to exercise this option validates the utility of our XTEN technology,” said Volker Schellenberger, PhD, Amunix President and Chief Executive Officer.  “The initial research collaboration resulted in the discovery of molecules that are clearly differentiated from current Factor VIII products in that they retain procoagulant activity while having unprecedented half-life in animal models,” Dr. Schellenberger added.  “Collaborations such as ours with Biogen Idec are a central element of the Amunix strategy to facilitate the use of XTEN in a wide range of therapeutic applications.”

About Amunix

Amunix Operating Inc., a biotechnology company headquartered in Mountain View, CA, has developed a novel half-life extension technology based on XTEN; hydrophilic, unstructured polypeptides which can be recombinantly fused or chemically conjugated to other peptides, proteins and small molecules.  Through this proprietary XTEN technology, the company creates and develops novel versions of clinically-proven pharmaceutical products that may offer better efficacy, safety and dosing frequency by extension of the half-life.  Two XTEN products, Exenatide-XTEN (VRS-859) and hGH-XTEN (VRS-317), have completed Phase 1 studies through Amunix partners Diartis and Versartis, respectively.  Versartis is currently conducting a Phase 2a study with VRS-317 in pediatric growth hormone deficient patients.  In addition to its partnership with Biogen Idec, Amunix is working with Janssen Biotech, Inc. and its affiliates to apply the XTEN half-life extension technology with protein and/or peptide therapeutics selected by Janssen.  Amunix has several other undisclosed partners in various therapeutic areas.   Founded in 2006, Amunix is a profitable, independent biotechnology company with no external investors.  Amunix is actively seeking partnerships for application of its XTEN technology. For additional information about the company, please visit