Abgenix and SangStat Receive Orphan Drug Designation for ABX-CBL for Treatment of Acute Graft Versus Host Disease.

Business Editors, Health/Medical Writers

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

Abgenix, Inc. (Nasdaq:ABGX), and SangStat (Nasdaq:SANG) reported today that ABX-CBL has been granted orphan drug designation for the treatment of acute graft-versus-host disease by the U.S. Food and Drug Administration (FDA). ABX-CBL, an antibody developed by Abgenix, is a murine anti-CD147 monoclonal antibody for the treatment of steroid-resistant graft versus host disease (GVHD), and is currently in a multi-center, randomized and controlled Phase II/III study. Approximately 25% of patients that undergo an allogeneic bone marrow transplant develop steroid resistant GVHD, for which there is currently no standard approved therapy available.

Orphan drug designation is granted to applicants when the prevalence of the disease occurs in less than 200,000 patients in the United States. The advantages of this designation include: exemption from the user fee; seven-year marketing exclusivity to the sponsor who obtains marketing approval for the designated orphan drug product, beginning on the date that a marketing application is approved by the FDA; tax credits for development costs; and eligibility for research grants to conduct clinical trials. These advantages are intended to encourage sponsors to develop drugs for patients with rare diseases.

"This is a very positive development in the ABX-CBL program, particularly on the eve of this week's American Society of Hematology meeting in San Francisco, which is one of the premier bone marrow transplant/hematology meetings," said Jean-Jacques Bienaime, Chairman, CEO and President of SangStat.

In August 2000, Abgenix and SangStat entered into a global co-development, supply and license agreement for ABX-CBL. Under the agreement, SangStat will have an exclusive worldwide license for the marketing and sale of ABX-CBL and, subject to the terms and conditions of the agreement, the right to commercialize other anti-CD147 antibodies. Abgenix will be responsible for manufacturing ABX-CBL. Development costs will be shared equally, as would any potential profits from sales of collaboration products. SangStat and Abgenix will share responsibility for product development, including the ongoing trial.

The Phase II/III study is designed to demonstrate statistically significant efficacy of a single dose level of ABX CBL in comparison to a control group of patients. In an earlier Phase II trial completed in the fall of 1999, 52% of patients receiving 0.1 - 0.3 mg/kg ABX-CBL survived at least 100 days following initiation of therapy, compared to 22% of patients receiving the presumed no effect dose of 0.01 mg/kg.

Abgenix Inc.

Abgenix is a biopharmaceutical company focused on the development and commercialization of antibody therapies for a variety of diseases. The company developed XenoMouse(TM)technology to enable the rapid generation of high affinity, fully human antibody product candidates to essentially any disease target appropriate for antibody therapy. Abgenix uses its XenoMouse technology to build a large and diversified product portfolio through the establishment of licensing arrangements with multiple pharmaceutical, biotechnology and genomics companies, and through the development of its own internal proprietary products. For more information on Abgenix, visits the company's website at www.abgenix.com.

SangStat

SangStat is a global biotechnology company building on its foundation in transplantation to discover, develop and market high value therapeutic products in the transplantation, immunology and hematology/oncology areas. Since 1988, SangStat has been dedicated to improving the outcome of organ and bone marrow transplantation through the development and marketing of products to address all phases of transplantation in the worldwide market. SangStat's US headquarters are in Fremont, California. SangStat also maintains a strong European presence, including direct sales and marketing forces in France, Germany, Italy, Spain, and the U.K., and distributors throughout the rest of the world. SangStat's stock is traded on the Nasdaq under the symbol "SANG". The company's web site is located at www.sangstat.com.

Statements made in this press release about Abgenix's XenoMouse technology, product development activities, and collaborative arrangements other than statements of historical fact, are forward looking statements and are subject to a number of uncertainties that could cause actual results to differ materially from the statements made, including risks associated with the success of clinical trials, the progress of research and product development programs, the regulatory approval process, competitive products, future capital requirements and the extent and breadth of Abgenix's patent portfolio. Please see Abgenix's public filings with the Securities and Exchange Commission for information about risks that may affect Abgenix.

This press release contains forward-looking statements that involve risks and uncertainties, including statements regarding SangStat's product development, including clinical trials and the regulatory process. Forward-looking statements reflect SangStat's current views with respect to future events. Actual results may vary materially and adversely from those anticipated, believed, estimated, or otherwise indicated. There can be no assurance that ABX-CBL will be safe, effective or capable of being manufactured in commercial quantities at an economical cost, that it will not infringe the proprietary rights of others or that it will achieve market acceptance. Other factors that could cause actual results to differ materially include, without limitation, delays in clinical trial enrollment or requests from the regulatory agencies for additional clinical trials either of which could delay regulatory filings and approvals. For a discussion of these and other factors that might result in different outcomes, see "Risk Factors" in SangStat's 1999 Annual Report on Form 10-K, its 2000 quarterly reports on Form 10-Q and other documents (including registration statements on Form S-3) filed with the Securities and Exchange Commission.