Press Release

Amunix Signs Research Collaboration With Biogen Idec For Next Generation Long-Lasting Blood Factor Products

Mountain View, CA – April 13, 2011 – Amunix, Inc., today announced that it has entered into an exclusive worldwide research collaboration and option agreement with Biogen Idec (NASDAQ: BIIB), to research and develop novel, fully-recombinant blood factors (Factors IX, VIII and VIIa) with improved therapeutic properties.  The partnership will combine Amunix’s protein half-life engineering expertise, based on its proprietary XTEN technology, and Biogen Idec’s broad range of capabilities in research, manufacturing and clinical development of recombinant blood factors for hemophilia.

“Biogen Idec is pleased to initiate research on this innovative technology in collaboration with Amunix,” said Glenn Pierce, Senior Vice President of Biogen Idec Hemophilia. “We have a long-term commitment to hemophilia.  In addition to advancing our current late-stage long-lasting Factor IX and Factor VIII programs, we continue to invest in innovations like XTEN, which have the potential to bring further-improved treatment options to the hemophilia community.”

Under the terms of the agreement, the companies will jointly conduct preclinical research. Biogen Idec will additionally be responsible for clinical development, manufacturing and commercialization of therapeutic candidates selected for further development.  Amunix will receive an initial upfront payment in addition to R&D funding.  Amunix will also be eligible to receive future milestone and royalty payments for therapeutic candidates chosen by Biogen Idec for development.  Additional financial terms will not be disclosed.

“We are pleased to be collaborating with Biogen Idec, a global leader in hemophilia therapeutics,” said Willem ‘Pim’ Stemmer, Ph.D., Chief Executive Officer of Amunix.  “Existing recombinant blood factor products require frequent intravenous infusions and there is strong medical need for products that can be dosed less frequently and more conveniently, and used prophylactically. In addition to further validating our XTEN technology platform, this collaboration with Biogen Idec demonstrates the potential of the Amunix XTEN technology for recombinant products that require manufacturing in mammalian cells.”

About Amunix

Amunix, Inc., based in Mountain View, CA, is a privately held biotechnology company focused on the discovery and development of novel therapeutics with improved dosing frequency and administration. The company’s patented platform technology, XTEN, involves the genetic fusion of a clinically proven payload protein to a long, unstructured, hydrophilic amino acid sequence to extend protein half life.  The two most advanced XTEN-based products are being developed by Versartis, Inc. and Diartis Pharmaceuticals, Inc., under licenses from Amunix.  Both companies are currently in Phase I clinical studies with their respective products: Versartis – VRS-317 for growth hormone deficiency, and Diartis – VRS-859 for type 2 diabetes mellitus.  Amunix is also developing a broad pipeline of other XTEN-based products. For more information about Amunix, please see