Xencor Reaches Research Milestone.

Business Editors/Health & Medical Writers

BIOWIRE2K

MONROVIA, Calif.--(BW HealthWire)--June 17, 2002

Xencor today announced that it has reached a major milestone in its research agreement with Syngenta's (NYSE: SYT) Torrey Mesa Research Institute (TMRI). In just six months, half the time agreed upon, Xencor has created and delivered optimized protein candidates that will enable Syngenta to develop novel consumer products for the food and feed industries.

"Xencor's technology has proven to be very valuable to our research efforts. Xencor's speed and efficiency in identifying protein candidates is critical to the success of our new business strategy," said Dr. Steven Briggs, head of genomics for Syngenta and president of TMRI. "We look forward to working closely with Xencor to develop optimized proteins that will further expand new product development opportunities for Syngenta."

In January, TMRI announced the signing of a three-year agreement with Xencor, with critical milestones at the end of the first year, focusing on the discovery of novel proteins with commercial applications. Xencor used its Protein Design Automation(TM) (PDA(TM)) technology to optimize TMRI protein leads.

"Having delivered ahead of schedule is a validation of our in silico protein optimization approach," said Bassil Dahiyat, Ph.D., president and CEO of Xencor. "By merging supercomputing with experimental screening we are able to overcome the limits of natural and directed evolution -- creating proteins in record time with features tuned for TMRI's applications. Our PDA(TM) technology created multiple candidates that exceeded TMRI's technical specifications."

Xencor's PDA(TM) technology is the first method to combine advanced computational methods, high performance computing and experimental screening for protein optimization and sequence design. Xencor uses the information embedded in protein structure to optimize the function of a protein including its activity, binding affinity and specificity, stability, expression level, and potency.

Xencor, a privately held company, is focused on using its cutting edge protein analysis and optimization technologies to accelerate the discovery of therapeutic proteins and novel compounds. With its proprietary ProCode(TM) and PDA(TM) technologies, Xencor scientists can rapidly determine the interactions and functions of a cell's entire protein complement, identify proteins of interest, and then optimize key properties of these proteins to fit commercial applications. The use of these technologies alone, or in combination, will accelerate the compound identification and development programs of Xencor's strategic partners in the pharmaceutical, biotechnology, and agricultural and chemical industries. Further information is available at www.xencor.com.

Torrey Mesa Research Institute (www.tmri.org)

La Jolla, California-based Torrey Mesa Research Institute is one of the largest single research endeavors dedicated to agricultural genomics research and development. Syngenta, which acquired the organization in January 2001, is a world-leading agribusiness. The company ranks first in crop protection, and third in the high-value commercial seeds market. Sales in 2001 were approximately US $6.3billion. Syngenta employs more than 20,000 people in over 50 countries. The company is committed to sustainable agriculture through innovative research and technology. Syngenta is listed on the Swiss stock exchange and in London, New York and Stockholm. Further information is available at www.Syngenta.com.

This press release contains forward-looking statements, which can be identified by terminology such as "expect," "would," "will," "potential," "plans," "prospects," "estimated," "aiming," "on track," and similar expressions. Such statements may be subject to risks and uncertainties that could cause the actual results to differ materially from these statements. We refer you to Syngenta's publicly available filings with the U.S. Securities and Exchange Commission for information about these and other risks and uncertainties. Syngenta assumes no obligation to update forward-looking statements to reflect actual results, changed assumptions or other factors. This release does not constitute, or form part of, any offer or invitation to sell or issue, or any solicitation of any offer, to purchase or subscribe for any ordinary shares in Syngenta AG, or Syngenta ADSs, nor shall it form the basis of, or be relied on in connection with, any contract therefore.