March 25, 2004

News Release: GSK Invests in New Production Facility for Rotarix, AVANT Immunotherapeutics'Rotavirus Vaccine, According to Reuters Report

AVANT Immunotherapeutics, Inc. (Nasdaq: AVAN) today announced that, according to a report by the Reuters news agency, GlaxoSmithKline (GSK) plans to invest approximately 450 million euros in a new facility in Belgium. The report stated that GSK will use this facility in part to develop, produce and conduct quality control on Rotarix(R), the rotavirus vaccine partnered with AVANT. The production plant is reportedly scheduled to come on line by 2005.

'This report is a strong indication that Rotarix(R) is in very advanced stages of development by GSK,'said Una S. Ryan, Ph.D., AVANT President and Chief Executive Officer. 'AVANT is very pleased that our partner is clearly planning for the near-term commercialization of Rotarix(R), as evidenced by their commitment to this new facility for vaccine production.' Rotarix(R) is a two-dose, oral rotavirus vaccine created by AVANT and licensed to GSK for development and commercialization. GSK began a Phase III trial of Rotarix(R) in 60,000 infants in Latin America and South East Asia during 2003. Based on positive results from this trial for which a majority of children have already been vaccinated - as well as data from over 6,500 previously vaccinated children - GSK plans to commercialize Rotarix(R) in the European Union and other international markets before seeking marketing approval in the United States. Rotavirus infection causes potentially life-threatening diarrhea and dehydration in infants. This virus kills a child every minute in the developing world and causes over 2 million hospitalizations globally.

AVANT Immunotherapeutics, Inc. discovers, develops and sells innovative vaccines and therapeutics that harness the human immune system to prevent and treat disease. The company has developed a broad, well-staged pipeline of vaccines and therapeutics for large, high-value, under-served markets. Six of AVANT's products are in clinical development. These include an oral human rotavirus vaccine, a treatment to reduce complement-mediated tissue damage associated with cardiac by-pass surgery, and a novel vaccine for cholesterol management. AVANT has also assembled a technology platform that enables the creation of rapid-protecting, single-dose, oral vaccines that remain stable without refrigeration. The company is developing applications of this vaccine technology in four areas: biodefense, travelers'vaccines, global health needs, and human food safety. AVANT's goal is to demonstrate proof-of-concept for its products before leveraging further development through both traditional pharmaceutical partnerships and collaborations with governmental and other organizations.

Additional information on AVANT Immunotherapeutics, Inc. can be obtained through our site on the World Wide Web: http://www.avantimmune.com.

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995: This release includes forward-looking statements which reflect AVANT's current views with respect to future events and financial performance. These forward-looking statements are based on management's beliefs and assumptions and information currently available. The words 'believe', 'expect', 'anticipate', 'intend', 'estimate', 'project'and similar expressions which do not relate solely to historical matters identify forward-looking statements. Investors should be cautious in relying on forward-looking statements because they are subject to a variety of risks, uncertainties, and other factors that could cause actual results to differ materially from those expressed in any such forward-looking statements. These factors include, but are not limited to: (1) the integration of multiple technologies and programs; (2) the ability to adapt AVANT's vectoring systems to develop new, safe and effective orally administered vaccines against anthrax and plague or other bioterrorism threats or emerging health care threats; (3) the ability to successfully complete development and commercialization of TP10, CETi-1, CholeraGarde(TM) (Peru-15), Ty800 and other products; (4) the cost, timing, scope and results of ongoing safety and efficacy trials of TP10, CETi-1, CholeraGarde(TM) (Peru-15), Ty800 and other preclinical and clinical testing; (5) the ability to successfully complete product research and further development, including animal, pre-clinical and clinical studies of TP10, CETi-1, CholeraGarde(TM) (Peru-15), Ty800 and other products; (6) the ability of the Company to manage multiple late stage clinical trials for a variety of product candidates; (7) the volume and profitability of product sales of Megan(R)Vac 1, Megan(R)Egg and other future products; (8) changes in existing and potential relationships with corporate collaborators; (9) the availability, cost, delivery and quality of clinical and commercial grade materials supplied by contract manufacturers; (10) the timing, cost and uncertainty of obtaining regulatory approvals to use TP10, CETi-1, CholeraGarde(TM) (Peru-15) and Ty800, among other purposes, for adults undergoing cardiac surgery, to raise serum HDL cholesterol levels and to protect travelers and people in endemic regions from diarrhea causing diseases, respectively; (11) the ability to obtain substantial additional funding; (12) the ability to develop and commercialize products before competitors; (13) the ability to retain certain members of management; and (14) other factors detailed from time to time in filings with the Securities and Exchange Commission. We expressly disclaim any responsibility to update forward-looking statements.

SOURCE: AVANT Immunotherapeutics, Inc.

AVANT Immunotherapeutics, Inc.Una S. Ryan, Ph.D., 781-433-0771orAVANT Immunotherapeutics, Inc.Avery W. Catlin, This email address is being protected from spambots. You need JavaScript enabled to view it. Media:Kureczka/Martin AssociatesJoan Kureczka, This email address is being protected from spambots. You need JavaScript enabled to view it.

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