AMBRX ASSEMBLES WORLD CLASS TEAM AND RAISES $12.5 MILLION TO APPLY BREAKTHROUGH TECHNOLOGY TO PROTEIN THERAPEUTICS

SAN DIEGO, California -- September 22, 2003 - Ambrx, Inc., a biopharmaceutical company with a mission to deliver breakthrough protein therapeutics, announced that Richard D. DiMarchi, Ph.D. has been appointed as founding Chief Executive Officer and Thomas O. Daniel, M.D. has joined the company as Chief Scientific Officer. In addition, Ambrx announced that it had closed a $12.5 million Series A preferred stock financing and obtained an exclusive license to its technology from The Scripps Research Institute.

Ambrx, founded by Peter G. Schultz, Richard DiMarchi and Troy E. Wilson, is based on pioneering technology developed by Schultz and his colleagues at The Scripps Research Institute. Ambrx's core technology represents a fundamental advance that enables the company to genetically engineer proteins with new amino acid building blocks beyond the common twenty, enabling the biosynthesis of proteins with new physical, chemical and pharmacological properties.

"I have participated in three decades of advances in protein and peptide chemistry, and I believe that Ambrx will pioneer the next leap in protein science, namely protein medicinal chemistry," commented Richard DiMarchi, formerly Group Vice President for Biotechnology at Lilly Research Laboratories. "As the founding CEO of Ambrx, my goal has been to assemble a world class leadership team and focus application of the technology on areas of significant unmet medical need."

"The introduction of defined chemical modifications into proteins will enable the creation of new and better medicines," commented Tom Daniel, a physician scientist and formerly Vice President, Research at Amgen, Inc. "Ambrx is the sort of opportunity that draws outstanding scientists together to make a transformational impact on science and human health."

"Richard DiMarchi and Tom Daniel bring an outstanding record of accomplishment and tremendous experience to Ambrx," stated Peter Schultz, Chairman of the Board of Ambrx. "Given their proven understanding of the challenges faced by the industry, their decision to join the company makes a strong statement about the commercial potential for Ambrx's technology."

Ambrx's investors in the Series A financing round included 5AM Ventures of Menlo Park and Tavistock Life Sciences of San Diego. In connection with the close of the financing, Shehan Dissanayake, Ph.D., CEO of Tavistock Life Sciences and John Diekman, Ph.D., Managing Partner of 5AM Ventures will join the Ambrx board of directors.

Dr. DiMarchi was formerly Group Vice President for Biotechnology and Product Development at Lilly Research Laboratories, where he made major contributions to Lilly in biotechnology and endocrinology. Dr. DiMarchi was directly involved in the discovery and development of several Lilly drugs, including Humulin(R), Humatrope(R), Evista(R), Xigris(R), and Forteo(R). He was a co-inventor of Humalog(R), the first biosynthetic protein approved for human use. Additionally, at Lilly he championed the introduction and integration of cutting-edge biotechnologies, including genomics, proteomics, high-throughput screening, and combinatorial chemistry. Dr. DiMarchi is presently a Professor of Chemistry and the Jack and Linda Gill Distinguished Chair in Biomolecular Science at Indiana University.

Dr. Daniel was formerly Vice President, Research at Amgen Inc., where he served as Research Site Head of Amgen Washington and Therapeutic Area Head of Inflammation. Prior to Amgen's acquisition of Immunex, Dr. Daniel was Senior Vice President of Discovery Research. At Immunex he consolidated and built programs in oncology and vascular biology, advanced candidate therapeutics in those areas, and forged programmatic emphasis on antibody therapeutics. A nephrologist and former academic investigator, Dr. Daniel was previously the K. M. Hakim Professor of Medicine and Cell Biology at Vanderbilt University, and Director of the Vanderbilt Center for Vascular Biology.

Dr. Schultz is currently Scripps Professor of Chemistry at The Scripps Research Institute and Director of the Genomics Institute of the Novartis Research Foundation. Dr. Schultz has made a number of major contributions to science including the discovery of catalytic antibodies, methodology that for the first time expands the genetic codes of living organisms, and the development and application of combinatorial methods in chemistry and biology including the first generation of combinatorial materials libraries. Dr. Schultz is a member of the National Academy of Sciences and the Institute of Medicine of the National Academy of Sciences. He is active on many editorial and scientific advisory boards and is a founding scientist of Affymax Research Institute and co-founder of Symyx Technologies, Syrrx, Kalypsys, and Phenomix.

About Ambrx
Ambrx, Inc. is a biopharmaceutical company with a mission to deliver breakthrough protein therapeutics. Ambrx is based on a fundamental advance in protein biosynthesis that enables the company to genetically engineer proteins with new amino acid building blocks beyond the common twenty, enabling the biosynthesis of proteins with new physical, chemical and pharmacological properties. By combing the versatility of medicinal chemistry with modern biotechnology, Ambrx is transforming the field of protein-based medicines. Ambrx completed a $12.5 million Series A preferred stock financing from investors including 5AM Ventures and Tavistock Life Sciences. Ambrx is based in San Diego, California and is currently recruiting a world-class scientific and commercialization team. For more information, please visit www.ambrx.com.

For further information, please contact Troy Wilson, Ph.D., J.D., Chief Business Officer of Ambrx, Inc. at (858) 731-3542 or Liz Thompson, Ph.D. at Atkins + Associates at (858) 527-3942.