Positive Results from Versartis, Inc. Phase 1 Clinical Study of Once Monthly Human Growth Hormone Treatment Presented at ENDO 2012

HOUSTON, TX--(Marketwire - June 25, 2012) - Versartis, Inc., an emerging biotechnology company developing novel therapeutics for patients with endocrine disorders, today presented the first results from its recent clinical trial of VRS-317, the company's proprietary once monthly form of recombinant human growth hormone (rhGH). The oral discussion of "A Phase 1 Trial of Safety, Pharmacokinetics (PK) and Pharmacodynamics (PD) of a Single Dose of a New Human Growth Hormone Analogue (VRS-317) for Monthly Subcutaneous Administration in Adults with Growth Hormone Deficiency (GHD)" was presented this morning by Versartis Vice President of Medical Affairs George M. Bright, MD, at ENDO 2012: The 94th Annual Meeting of the Endocrine Society.

Dr. Bright stated, "The human clinical data presented today shows that a single dose of VRS-317 was very well tolerated and can be administered at or below the average-equivalent daily rhGH dose over 30 days to safely sustain normalized serum IGF-1 levels in adult growth hormone deficient patients."

"These clinical results further confirm our previous findings that VRS-317 is currently the only long acting rhGH compound with the potential for monthly dosing," commented Versartis Chief Executive Officer Jeffrey L. Cleland, PhD. "VRS-317 may provide a less frequent but equally efficacious treatment for growth hormone deficiency than currently available daily rhGH therapies. We look forward to continued development of this product to improve the lives of GHD patients."

VRS-317 Phase 1 Clinical Trial
The primary objective of the Phase 1 study was to evaluate the safety and tolerability of a single subcutaneous (SC) dose of VRS-317. The 60-day, double-blind, randomized, placebo-controlled, single-ascending dose Phase 1 trial enrolled 50 GHD adult patients in the United States and Europe. Initially, subjects took daily rhGH (min. 28 days, dose range 0.2-1.2 mg/d) until their IGF-1 standard deviation scores (SDS) were stable in the range of -1.5 and +1.5 (frequently referred to as the normal range). Patients were then withdrawn from rhGH until the IGF-I SDS was < -1.0 and had fallen by ≥ 0.75. PK, PD, and glucose and lipid metabolism markers were measured pre-dose and at various times over 30 days after a single SC dose of VRS-317 or placebo. After the withdrawal period, patients received a single subcutaneous dose of 0.05, 0.10, 0.20, 0.40 or 0.80 mg/kg VRS-317 or placebo. These doses of VRS-317, expressed as a daily-equivalent dose of rhGH, were 0.0003, 0.0006, 0.0012, 0.0024 and 0.0048 mg/kg per day over 30 days. In practice, adult GHD patients utilize doses ranging from 0.002 to 0.0125 mg rhGH/kg per day in order to maintain their IGF level in the normal range. Thus, the VRS-317 doses studied in this trial spanned the lower half of the typical amount of daily rhGH utilized for these patients. The extent and duration of pharmacodynamic responses to VRS-317 (or placebo) was evaluated in each patient and compared to prior daily rhGH therapy.

Top Line Results
Results presented by Dr. Bright demonstrated that single doses of VRS-317 were safe and well tolerated. Adverse events (AEs) that were considered drug related were primarily mild and transient. There were no reported SAEs, no unexpected AEs and no injection site lipoatrophy observed during treatment. No significant post-dosing changes were observed for fasting glucose, post-prandial glucose or fasting insulin. Substantial reductions in cholesterol, triglycerides and LDL were observed in GHD patients receiving 0.80 mg/kg VRS-317.

The PK profile of VRS-317 was presented for all dose levels in the study. At doses from 0.20 to 0.80 mg/kg VRS-317, a dose-proportional linear increase in exposure (AUC) and Cmax was observed. VRS-317 was rapidly absorbed achieving a Tmax 2-3 days after a single SC dose. The half-life of VRS-317 increased significantly (p=0.016) as a linear function of increased dose with a maximum mean terminal half-life of 131 hours at the 0.80 mg/kg dose of VRS-317.

The PD profile of VRS-317 indicated that IGF-1 was normalized in a dose-dependent manner with the duration of IGF-1 normalization increasing with dose. Adult GHD patients with a pre-dose IGF-1 SDS below -1.5 had a mean sustained IGF-1 SDS above -1.5 for up to 3 weeks after a single 0.80 mg/kg VRS-317 dose. In addition, the mean maximum IGF-1 SDS in this group was less than +1.5, suggesting that further dose escalation may safely achieve sustained IGF-1 in the normal range for at least one month. These results demonstrate that single doses of VRS-317 sustained IGF-1 responses in the normal range in a dose dependent and tunable manner, enabling dose regimens of up to monthly for future clinical trials.

NOTE: The company's extensive preclinical safety and efficacy data for VRS-317 were recently published in The Journal of Pharmaceutical Sciences (7 JUN 2012 | DOI 10.1002/jps.23229): "A Novel Long-Acting Human Growth Hormone Fusion Protein (VRS-317): Enhanced In Vivo Potency and Half-Life." Amongst other key preclinical findings, VRS-317 provided comparable biological activity and safety to daily rhGH with a lower total monthly dose of rhGH and these results were used as the basis for the company's Phase 1 clinical trial.

About Versartis
Versartis, Inc. is a biotechnology company developing therapeutics for the treatment of endocrine disorders. The company's lead product candidate is VRS-317, a once monthly form of human growth hormone. Versartis is pursuing the development of new therapeutic proteins utilizing the proprietary Amunix half-life extension XTEN technology. XTEN is a novel hydrophilic sequence of natural amino acids and is expressed as a fusion protein with a therapeutically active peptide or protein. New compounds developed by Versartis using the XTEN technology are expected to provide improved therapeutic outcomes such as enhanced efficacy/compliance, fewer side effects, prolonged half-life (up to monthly dosing), as well as low-cost production and enhanced stability. Further information on Versartis can be found at www.versartis.com.