Press Release

Preclinical Data from Biogen Idec-Amunix Partnership Presented at ISTH Congress

– Presentations Feature Amunix XTEN Half-Life Extension Technology for FVIII and FVIIa –

MOUNTAIN VIEW, CA – (Marketwired – July 1, 2013) – Amunix Operating Inc. (Amunix) announced that the first of five presentations made by Biogen Idec – featuring preclinical research from the company’s XTEN technology partnership – was presented today at the XXIV International Society on Thrombosis and Haemostasis (ISTH) Congress in Amsterdam. During the course of the meeting, Biogen Idec investigators will present data on novel coagulation factor compositions utilizing the proprietary XTEN technology developed at Amunix (see schedule of presentations below).

Presentations will feature preclinical findings utilizing Amunix XTEN technology to create a new class of Factor VIII (FVIII) molecules that achieved a circulating half-life of up to 30 hours in mice, representing a four-fold improvement over currently-marketed FVIII products. Data will also be presented from the partnership’s Factor VIIa program to develop products with targeted delivery and increased half-life, representing a potential new option for patients with hemophilia who have inhibitory antibodies that make coagulation factor replacement ineffective.

“Our work with Biogen Idec has been extremely productive and is a validation of the utility of Amunix’s XTEN technology,” said Volker Schellenberger, PhD, Amunix President and Chief Executive Officer.   “This research collaboration resulted in the discovery of molecules that are clearly differentiated from competing FVIII products, as described in the presentations at ISTH this week.”  Dr. Schellenberger added, “Collaborations such as our Biogen Idec hemophilia research are a central element of our strategy to facilitate the use of XTEN in a wide range of therapeutic applications.”

Robert Peters, PhD, Senior Director of Hemophilia Research at Biogen Idec, elaborated, “We have taken advantage of the flexibility of the XTEN technology, in combination with our internal research efforts to escape the limitations von Willebrand factor imposes on FVIII half-life, to generate unique fusion proteins in our preclinical FVIII program. These novel FVIII fusion proteins exhibited half-lives in hemophilia A mice twice as long as preclinical results for the long-lasting technologies currently being assessed in clinical trials.”

ISTH Presentations from the Biogen Idec-Amunix collaborations (CEST):

A Platelet-Targeted Factor VIIa – XTEN Fusion Protein with Increased Circulating Half-Life and Improved Clotting Activity – e-Poster PB 1.58-1 – Monday, July 1 – 17:00-18:30

Effect of Unstructured Polypeptide Insertions on the Recombinant Expression of Human FVIII – e-Poster PB 2.55-3 – Tuesday, July 2 – 17:00-18:30

A combinatorial library approach to generate rFVIII variants with multiple XTEN insertions and improved pharmacokinetic properties – e-Poster PA 2.12-5 – Tuesday, July 2 – 17:00-18:30

Identification of Structurally Permissive Regions in Coagulation Factor VIII Suitable for the Insertion of Exogenous Peptidyl Elements – e-Poster PB 4.55-4 – Thursday, July 4 – 13:30-15:00

A New Class of Coagulation Factor VIII Molecules that Achieved Four-Fold Longer Half-Life than Recombinant FVIII in Hemophilia A Mice – Oral Platform AS 45.1 – Thursday, July 4 – 16:00-16:15

Session details and presentations for the 2013 Congress can be found on the ISTH website at and the Biogen Idec press release

XTEN for FVIII Products

Since recombinant FVIII was first marketed in the 1980’s, there have been considerable efforts to develop long-acting FVIII products.  Many different approaches have been pursued and significant improvements have been achieved; however gains in half-life were less than two-fold relative to native FVIII. Biogen Idec’s preclinical data demonstrate a four-fold improvement compared to commercially-available products.  Combining Biogen Idec’s expertise in hematology with Amunix’s XTEN technology, the FVIII project took full advantage of Amunix’s ability to introduce multiple XTEN chains into a protein to retain activity and increase half-life, as well as enhance other pharmaceutical properties. Both the locations as well as the length of these XTENs were optimized to achieve best-in-class half-life in hemophilia A mice.

About the Biogen Idec and Amunix Collaboration

Biogen Idec and Amunix Operating Inc. entered into an exclusive, worldwide research collaboration and option agreement in early 2011 to research and develop novel, fully-recombinant blood factors (Factors IX, VIII and VIIa) with improved therapeutic properties.  The partnership combines Amunix’s protein half-life engineering expertise, based on its proprietary XTEN technology, with Biogen Idec’s broad range of capabilities in research, manufacturing and clinical development of recombinant blood factors for hemophilia.

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 1a studies through Amunix partners Diartis and Versartis, respectively.  Versartis is currently conducting a Phase 1b/2a study in pediatric growth hormone deficient patients with VRS-317.  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