Long-Acting hGH Analogue Requires Only Weekly Dosing

SAN DIEGO, Nov. 13 /PRNewswire/ -- Ambrx Inc. today announced Phase I/II clinical trial data demonstrating that ARX201, the company's long-acting human growth hormone (hGH) analogue developed in collaboration with Merck Serono, normalized insulin-like growth factor I (IGF-I) levels while delivering an acceptable safety and tolerability profile in adults with Growth Hormone deficiency. The results of this trial support further evaluation of ARX201 as an option for the treatment of adult growth hormone deficiency (AGHD).

In the 26-week study, normal levels of IGF-I, a marker for hGH activity, were maintained with injections given once a week. The clinical trial results were presented today at the International Congress of Endocrinology Conference in Rio de Janeiro by Andrew Hoffman, M.D., Professor of Medicine and Vice Chair for Academic Affairs at Stanford University.

"We are very excited by these promising clinical results and are hopeful that ARX201 will provide a better treatment option for patients with AGHD that currently require daily injections," said Stephen Kaldor, Ph.D., president and CEO of Ambrx. "Additionally, this study provides proof of concept that protein analogues made using Ambrx's ReCODE(TM) technology have retained potency with an improved pharmacological profile over conventional protein therapeutics. This opens the door for Ambrx to create more effective protein-based therapies across a broad range of treatment classes."

The Phase I/II study of ARX201, analyzed 22 AGHD patients who had not received hGH replacement therapy in the six months prior to the trial. ARX201 was administered by subcutaneous injection on a weekly basis for 26 weeks. IGF-I levels increased to normal values and remained such throughout the course of the trial. Patients experienced a mean truncal fat loss of 5.6 percent and a mean total body fat loss of 1.3 percent. The mean increase in lean body mass was 3.6 percent. ARX201 was well tolerated with temporary pain at the injection site as the only reported side effect. No neutralizing antibodies to either PEGylated GH or to native GH were detected throughout the study.

About ARX201

ARX201 is a long-acting recombinant human growth hormone drug candidate currently developed by Ambrx and Merck Serono for the treatment of growth hormone deficiencies. ARX201 was generated through a lead optimization process using Ambrx's ReCODE(TM) technology, which effectively enables protein medicinal chemistry. Through this approach, Ambrx was able to generate site specific mono-pegylated hGH molecules that were optimized for potency and time of action. Ambrx believes that ARX201 may have improved pharmacological performance over existing growth hormone products, including the potential for less frequent dosing.

In pre-clinical studies, ARX201 met or exceeded key end points in assays that are believed to be predictive of human pharmacokinetics and biological response. In February 2007, a Phase I/II clinical trial of ARX201 was initiated to investigate the safety, tolerability, pharmacokinetic and pharmacodynamic profile of this product candidate in adult patients with growth hormone deficiency following single-dose escalation and repeated dosing.

About Ambrx

Ambrx Inc. is a clinical stage biopharmaceutical company with a broad biologics platform that allows it to create best-in-class protein therapeutics, including improved versions of native proteins and therapeutic antibodies. Its most advanced product candidate, ARX201, is a long-acting human growth hormone drug candidate partnered with Merck Serono that has successfully completed initial clinical trials. The company has further validated its biologics platform through substantial partnerships with Eli Lilly and Company and Merck & Co. Ambrx is advancing a robust portfolio of product opportunities spanning multiple therapeutic areas that are highly optimized for efficacy, safety, and ease of use. For additional information, call 858.875.2400 or visit www.ambrx.com.

    Media Contacts:
    Heidi Chokeir or David Schull
    Russo Partners, LLC
    (619)814-3512
    heidi.chokeir@russopartnersllc.com
    david.schull@russopartnersllc.com

SOURCE Ambrx Inc.