Cerus Receives FDA Concurrence to Expand Inclusion Criteria for Phase III INTERCEPT Red Blood Cell Trial in Chronic Indications.

Business Editors/Health/Medical Writers

CONCORD, Calif.--(BUSINESS WIRE)--March 31, 2003

Cerus Corporation (Nasdaq:CERS) today announced that the United States Food and Drug Administration has concurred with expanding the inclusion criteria for patients in the pivotal Phase III trial for INTERCEPT Red Blood Cells for chronic transfusion support. The INTERCEPT Blood System, being jointly developed by Cerus and subsidiaries of Baxter International Inc., is a pathogen inactivation system to protect patients against transmission of infectious diseases through transfusions. The protocol revision will expand the trial population to include those receiving scheduled exchange transfusions, a method to reduce iron accumulation in patients who require chronic blood transfusions.

"We are pleased to receive concurrence to broaden our chronic trial recruitment to red blood cell exchange patients who receive large amounts of donor red cells," said Laurence Corash, M.D., chief medical officer for Cerus. "While Institutional Review Board approval at each clinical trial site must also be obtained, these expanded inclusion criteria will broaden our reach in the chronic patient population and are expected to facilitate more rapid enrollment in the trial, which is approximately 40 percent enrolled."

In addition, the companies reached concurrence with the FDA to revise the "Informed Consent" form signed by patients on the study. The new form reflects additional favorable safety data generated on the product.

The multicenter, double-blind, randomized Phase III trial is expected to enroll 50 patients who require red blood cell transfusion support for the treatment of chronic anemia due to the hereditary disorders sickle cell anemia and thalassemia. Each patient will receive red blood cells treated with the INTERCEPT Blood System and conventional red blood cells which are not prepared with a pathogen inactivation process. The primary endpoint of the trial is a comparison of the amount of INTERCEPT red blood cells and conventional red blood cells transfused to manage the patients' chronic anemia.

Patients who receive chronic transfusion therapy for sickle cell disease or thalassemia are typically exposed to approximately 200 milligrams of iron per red cell unit and are at risk of iron accumulation. Extensive exposure to iron can induce iron toxicity, which may be fatal. In an exchange transfusion, a portion of the patient's defective circulating red cell mass is removed and replaced with normal donor red cells, so that the amount of transfused iron can be significantly reduced.

The chronic Phase III trial is one of two pivotal trials the companies are conducting for the INTERCEPT Blood System for red blood cells. The other trial is a 200-patient trial comparing the use of INTERCEPT red blood cells to conventional red blood cells in an acute transfusion support setting. Data from the two trials are expected to support both European CE Mark and U.S. PMA registration applications.

Red blood cells are disc-shaped cells containing hemoglobin, which delivers oxygen from the lungs to the rest of the body. Red blood cells are the most frequently transfused blood component, with an estimated 34 million units being transfused each year in North America, Europe and Japan. Patients typically receive red blood cell transfusions to offset blood loss after trauma and during surgery, or to increase hemoglobin levels in patients with chronic anemia.

About Cerus

Cerus Corporation is building on its leading position in the biopharmaceutical industry by developing medical systems and therapeutics to provide safer and more effective options to patients. The company is developing products based on its proprietary Helinx(R) technology for controlling biological replication. Cerus' most advanced programs are focused on systems to enhance the safety of the world's blood supply. The INTERCEPT Blood System, which is being developed in collaboration with Baxter Healthcare Corporation, is based on the company's Helinx technology. The Intercept Blood System is designed to inactivate viruses, bacteria, other pathogens and white blood cells. The Concord, California-based company also is pursuing therapeutic applications of Helinx technology to treat and prevent serious diseases.

Helinx is a trademark of Cerus Corporation

INTERCEPT and INTERCEPT Blood are trademarks of Baxter International Inc.

Statements in this news release regarding clinical trials, regulatory filings, product development and commercial 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 risks and uncertainty of the timing, rates of enrollment and results of clinical trials and other development activities, actions by regulatory authorities at any stage of the development process, additional financing activities, manufacturing, market acceptance of any products, competitive conditions and other factors discussed in the companies' most recent filings with the Securities and Exchange Commission.