Cerus Corporation Receives U.S. Patent Covering Pathogen Inactivation in Red Blood Cells.

Business Editors/Health and Medical Writers

CONCORD, Calif.--(BW HealthWire)--Nov. 30, 2000

Cerus Corporation (Nasdaq:CERS) today announced that the U.S. Patent and Trademark Office has issued a patent to Cerus relating to the company's proprietary method for inactivating viruses, bacteria and other pathogens in compositions containing red blood cells. The patent, number 6,143,490, covers methods for using specific types of chemical compounds that bind DNA or RNA of pathogens to block their replication. The technology currently is being applied in the company's Intercept Red Blood Cell System, which is being developed jointly with Baxter Healthcare Corporation.

"With the addition of this patent to our portfolio, we continue to strengthen our proprietary position in inactivating viruses, bacteria and other pathogens in donated blood components," said Stephen T. Isaacs, president and chief executive officer of Cerus. "We continue to proactively protect our scientific know-how in this field which, we believe, will be essential as we pursue commercialization with our innovative Intercept Blood Systems."

The method-of-use patent follows a composition of matter patent, number 6,093,725, which was issued to the company in July, 2000. The composition patent covers Cerus' proprietary compound, S-303, and related compounds, which interact with DNA or RNA and result in inactivation of viruses, bacteria and other pathogens.

Cerus Corporation is developing medical systems and therapeutics that are based on the company's proprietary Helinx technology for targeting DNA and RNA to control biological replication. The company's most advanced programs are focused on systems to enhance the safety of the world's blood supply. These Intercept Blood Systems, based on the Helinx technology, are designed to inactivate viruses, bacteria and other pathogens. The Concord, California-based biopharmaceutical company, in collaboration with its development and commercialization partner Baxter Healthcare Corporation, has completed a European Phase III clinical trial of the Intercept Platelet System and is conducting further clinical trials of the Intercept Blood Systems in the United States: a Phase III trial for platelets, a Phase III trial for plasma and a Phase Ic trial for red blood cells.

Statements in this news release regarding product development, clinical development and product potential are forward-looking statements that involve risks and uncertainties. Actual results could differ materially from the above forward-looking statements as a result of certain factors, including the uncertainty of the timing and results of any clinical trials, action by regulatory authorities, the uncertainty of market acceptance of any products, competitive conditions, the uncertainty of future financing and other factors discussed in the company's 1999 Annual Report on Form 10-K and Prospectus dated November 1, 2000.

Note to Editors: Helinx is a trademark of Cerus Corporation. Intercept Blood System, Intercept Platelet System, Intercept Plasma System and Intercept Red Blood Cell System are trademarks of Baxter International, Inc. (NYSE:BAX).