MIAMI, Dec. 7 /PRNewswire/ -- Cerus Corporation (Nasdaq: CERS) presented data from preclinical studies which demonstrated that the company's proprietary S-59 technology prevented graft-versus-host-disease (GVHD) and enhanced engraftment in a mouse model of bone marrow transplantation. The data were presented at the American Society of Hematology (ASH) conference in Miami.

The first study showed that treatment of donor T-cells with the company's light-activated S-59 compound prevented the cells from replicating, while preserving cellular functions to facilitate transplant engraftment. The second study showed that mice transplanted with mismatched donor bone marrow cells and transfused with S-59 treated T-cells had improved engraftment and survival over mice transfused with mismatched bone marrow alone. Further, mice receiving treated T-cells did not develop GVHD, while those receiving untreated T-cell showed a 100% mortality rate from GVHD.

Bone marrow transplantation is a highly effective treatment for many forms of leukemia and other cancers. Bone marrow transplantation is most effective when the donor is identically matched to the patient for the major human lymphocyte antigen (HLA) groups. Identical matching is only possible for approximately 50% of patients. Patients receiving donor T-cells have a high risk of severe post-transplant complications, such as GVHD. GVHD, which has a high mortality rate, is caused by the proliferation of donor T-cells which attack tissue in patients' different bodily systems. The risk of GVHD is particularly high after chemotherapy or radiation therapy, which are common treatments for leukemia and lymphoma.

"Today, two of the most significant challenges facing bone marrow transplantation therapy are limited donor availability and the onset of GVHD," said Cerus president and chief executive officer Stephen Isaacs. "We hope the use of our technology with today's cell transplantation therapies can address both of these issues by decreasing the stringency of matching donors to patients and by eliminating the proliferation of donor T-lymphocytes which can cause GVHD. These are very positive data and we intend to use these results to support an IND application we are preparing for the FDA."

"Bone marrow transplantation has made enormous progress in the past decade and often represents the only alternative for a very sick population of patients with diseases such as lymphoma and leukemia. Unfortunately, successful outcomes are achieved in only a fraction of patients for many reasons, including the difficulty in striking the delicate balance between the therapeutic and potentially very dangerous effects of donor T-cells used in conjunction with cellular transplantation procedures," said Cerus vice president of medical affairs Laurence Corash, M.D. "A method to prevent the negative effects of mismatched T-cells in bone marrow grafts while retaining their beneficial properties would be a very significant advance in the field."

The Cerus allogeneic cellular immune therapy program is based on the company's proprietary light-activated psoralen compound, S-59. This compound has been developed to target and prevent the replication of nucleic acids such as DNA and RNA, which are required for cellular replication. The company is developing a system designed to prevent proliferation of donor T-cells while preserving the cells' therapeutic properties. The program is in preclinical evaluation.

In addition, Cerus Corporation is collaborating with the Fenwal Division of Baxter Healthcare Corporation to develop, manufacture and market pathogen inactivation systems for blood components (platelets, plasma and red blood cells) intended for transfusion. Programs for each of the three components are currently in clinical trials. 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. The Fenwal Division develops, manufactures and markets products and services for the collection, separation, storage and transfusion of blood and its components.

This news release contains 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, regulation by the FDA, the uncertainty of replication of animal data in humans, the uncertainty of market acceptance of any products, competitive conditions, the uncertainty of future financing and other factors discussed in the company's 1997 Annual Report on Form 10-K.