Flush with Cash, Versartis and Diartis Focus on Drugs Based on Amunix’ XTEN Technology

Young biotech firm Versartis raised $21 million through a Series B financing round led by New Leaf Venture Partners. The endocrine disorders drugs specialist says it aims to use the proceeds to continue clinical development of its lead once-monthly recombinant human growth hormone, VRS-317, for treating growth hormone deficiency (GHD) in both adult and pediatric patients. Additional investors in the Series B round included Advent Venture Partners’ Advent Life Sciences fund, along with existing investors Index Ventures and Amunix.

In parallel, newly founded biotech firm Diartis Pharmaceuticals received an initial investment from Index Ventures, Amunix, and private investors. The firm was established to take over from Versartis the development of VRS-859, a clinical-stage type 2 diabetes candidate.

Versartis was founded in 2008 as a joint venture between Index and Amunix, to develop extended-release formulations of drugs for endocrine disorders based on the latter’s XTEN half-life extension technology. The XTEN platform comprises a long, hydrophilic, unstructured polyamino acid tail, expressed as a fusion protein with the therapeutically active peptide or protein. Versartis claims the XTEN platform addresses the manufacturing and safety issues associated with the conjugation steps required in current PEGylation approaches, and could reduce the cost of goods by almost 10-fold relative to PEGylation.

VRS-859, an exenatide-XTEN diabetes drug candidate, is a once-monthly form of the GLP-1 analogue. A Phase Ia multicenter single-ascending dose study is currently evaluating the safety and ability of a single dose of VRS-859 to maintain glycemic control for one month in type 2 diabetes patients. Results from this trial are expected during the second quarter of 2011, and Diartis says it then plans to start a repeat-dose, three-month Phase Ib trial comparing VRS-859 with Byetta® (exenatide injection) in type 2 diabetes patients.

Diartis aims to expand its pipeline to the development of additional therapeutic proteins based on the Amunix XTEN platform. Amunix' own in-house pipeline conprises a range of preclinical-stage XTEN fusion proteins, including A1 antitrypsin, Factor IX, Factor VII, Factor VIII, and Glucagon. Additional once-monthly subcutaneous candidates are in development for the potential treatment of Crohn disease, cachexia, and inflammatory pain.