Press Release Details

Cerus Presents Data On Pathogen Inactivation Systems For Blood Transfusion Products

December, 06 1999
Cerus Corporation (Nasdaq: CERS) today reported key clinical data from three trials of the company's proprietary systems to inactivate viruses, bacteria and other pathogens in blood products intended for transfusion. The data, presented at the 41st annual meeting of the American Society of Hematology (ASH) in New Orleans, is from clinical trials of its pathogen inactivation systems in platelets, fresh frozen plasma (FFP) and red blood cells.

Platelet Program Data Demonstrates Viability and Hemostatic Function of Treated Platelets.

Data from the company's Phase 2c clinical trial of its proprietary pathogen inactivation system for platelet products demonstrated that S-59 treated platelets were as effective as untreated platelets in correcting bleeding times in patients with very low platelet counts. The data were presented by Dr. Sherrill Slitcher, Director of the Division of Research and Education, Puget Sound Blood Center, Seattle, WA. The trial, which enrolled eighteen platelet-deficient patients, evaluated the blood clotting ability of platelets treated with Cerus' proprietary S-59 compared to untreated platelets. In addition, the study demonstrated that the intervals between required transfusions were similar between S-59 treated and untreated platelets.

“It was important for us to demonstrate that S-59 treated platelets retained their therapeutic efficacy in patients with extremely low platelet counts before we moved into our U. S. Phase 3 clinical trial” said Dr. Laurence Corash, Vice President of Medical Affairs for Cerus. “The data show that the treated platelets were effective at stopping bleeding under these challenging conditions.”

Plasma Program Data Demonstrates Hemostatic Response in Patients Receiving Treated FFP.

Data from the company's Phase 2b study of its pathogen inactivation system for fresh frozen plasma showed that transfusion of S-59 treated FFP corrected blood clotting in patients with blood clotting deficiencies. Additionally, the S-59 treated FFP was well tolerated by the study patients. The trial, which included thirteen patients with chronic liver disease, examined the blood clotting response of patients receiving S-59 treated FFP compared to patients receiving untreated FFP. This study was a pilot study for Cerus' Phase 3 trial, which is currently ongoing.

Red Cell Program Data Demonstrates Viability of Treated Red Blood Cells. No Immune Response Detected.

Additionally, Dr. Julie Hambleton of the University of California, San Francisco presented data from the Phase 1b study for the company's program for the pathogen inactivation of red blood cells. The study, which included 28 healthy subjects each of whom received four small volume transfusion exposures to red blood cells treated with the company's proprietary S-303 compound over a 35 day period, demonstrated there was no detectable immune response directed against the treated blood cells. The study also showed that the viability of S-303 treated red blood cells after 35 days of storage exceeded the American Association of Blood Banks standard for 35 day old stored red blood cells.

“Once again, we were selected to present data from each of our three pathogen inactivation programs at the ASH conference,” said Stephen Isaacs, CEO and President of Cerus. “Our strong presence at this key medical conference underscores not only the progress we are making in our programs, but also the medical community's attention to pathogen inactivation as a potentially very significant advance in the safety of transfusion blood products.”

Abstracts from these clinical trials can be found on the Cerus website at

The Cerus pathogen inactivation systems for platelets and FFP are based on the company's proprietary light-activated psoralen compound, S-59, and its system for red blood cells is based on its proprietary pH-activated compound, S-303. These compounds have been developed to target and inactivate blood-borne pathogens, while leaving intact the therapeutic properties of the blood products. An estimated 3.5 million units of platelets are transfused annually worldwide to prevent bleeding in a broad range of patients, including those undergoing cancer therapy and surgical procedures. An estimated 10 million units of FFP are transfused annually worldwide in surgical settings and to prevent bleeding in a broad range of indications. An estimated 31 million units of red blood cells are transfused worldwide each year in surgical settings and to treat various indications ranging from severe trauma to genetic disorders.

The company's platform technologies, which prevent viral, bacterial and cellular replication, have potential applications in the health care field beyond pathogen inactivation in blood components. Cerus has ongoing clinical trials of its S-59 technology in the field of stem cell transplantation to treat leukemia and other hematologic malignancies.

Cerus Corporation is collaborating with the Fenwal Division of Baxter Healthcare Corporation to develop, manufacture and market pathogen inactivation systems for platelets, FFP and red blood cells used for transfusion. Baxter, a global medical products and services company, focuses on critical therapies for life-threatening conditions. Baxter is a leader in technologies related to blood and the circulatory system. Cerus is also collaborating with the Consortium for Plasma Science to develop pathogen inactivation systems for plasma for fractionation.

Statements in this news release regarding product development and clinical development 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 trials, uncertainties associated with regulation by the FDA, the uncertainty of replication of animal data in human and other factors discussed in the company's 1998 Annual Report on Form 10-K.

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