Amunix and XTEN are trademarks of Amunix Operating Inc., a company located in Mountain View, California USA (www.amunix.com). The PolyPeptide Group and Amunix Operating, Inc. have partnered to XTENylate therapeutic peptides.
XTEN™ is a custom designed recombinant protein based polymer that can be conjugated to peptides increasing their hydrodynamic radius and effective size. This reduces renal clearance from the bloodstream and protects against enzymatic degradation, thereby increasing the pharmaceutical half-life of the peptide. The principle is similar to that of PEGylation, but the key differentiator is that XTENylated peptides are biodegradable and do not accumulate in tissues. XTEN can be used to conjugate multiple copies of the same peptide and/or a limited number of different peptides or other molecules.
XTENylated peptides are readily analyzed and purified by HPLC because they are homogenous and monodisperse with precisely-controlled chemical structure. While XTENylated peptides can also be manufactured as fusion proteins, chemical conjugation offers a faster, more versatile and more economic approach to create a physically and biologically similar product. XTEN can be produced in large quantity by microbial fermentation and has been evaluated in multiple clinical trials.
PolyPeptide and Amunix have been collaborating on the development and manufacture of XTENylated peptides since 2011.