AVANT's Partner, GlaxoSmithKline, Files Rotarix(R) Application for U.S. Marketing Approval with the FDA.

NEEDHAM, Mass. -- AVANT Immunotherapeutics (Nasdaq: AVAN) today announced that its partner, GlaxoSmithKline (GSK) Biologicals, has filed a marketing application for the Rotarix([R]) vaccine with the United States Food and Drug Administration (FDA). Rotarix([R]) is a two-dose rotavirus vaccine given to children for the prevention of gastroenteritis caused by rotavirus.

"We are delighted that our partner GSK has filed for approval of Rotarix([R]) in the United States," said Una S. Ryan, Ph.D., President and Chief Executive Officer of AVANT Immunotherapeutics. "The FDA filing marks a significant milestone towards the global commercialization of Rotarix([R]), which has already been approved for commercial use in over 90 countries worldwide, including the European Union."

In May 2005, AVANT entered into an agreement whereby an affiliate of Paul Royalty Fund (PRF) purchased an interest in the net royalties AVANT will receive on worldwide sales of Rotarix([R]). The terms of the agreement with PRF include a $10 million milestone payment on product launch in 2008 in the United States. Under the PRF agreement, AVANT retains 50% of the GSK milestone payment triggered by U.S. approval of Rotarix([R]), with the balance payable to PRF and Cincinnati Children's Hospital Medical Center.

About Rotarix([R])

Rotarix([R]) is an oral, two-dose, live attenuated vaccine against rotavirus disease in infants that was licensed in 1997 by AVANT Immunotherapeutics to GSK for worldwide commercialization. The vaccine was originally developed at Cincinnati Children's Hospital Medical Center. Rotarix([R]) is the first human rotavirus vaccine derived from a human virus strain available in the market. The vaccine, which is given orally, confers significant protection against rotavirus diarrhea. Clinical trials have shown high efficacy against the most prevalent rotavirus strains. It is given in a two-dose schedule as of six weeks of age, allowing for early protection.

About AVANT Immunotherapeutics, Inc.

AVANT Immunotherapeutics, Inc. discovers and develops innovative vaccines and therapeutics that harness the human immune system to prevent and treat disease. AVANT has three products on the market and four of AVANT's products are in clinical development. AVANT's pipeline includes products for travelers' vaccines and global health needs based on AVANT's oral, rapid-protecting, single-dose and temperature-stable vaccine technology.

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 that are subject to a variety of risks and uncertainties and reflect AVANT's current views with respect to future events and financial performance. There are a number of important factors that could cause the actual results to differ materially from those expressed in any forward-looking statement made by AVANT. 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 any other microbes used as bioweapons and other disease causing agents; (3) the ability to successfully complete product research and further development, including animal, pre-clinical and clinical studies, and commercialization of CholeraGarde[R] (Peru-15), Ty800, ETEC E. coli vaccine, VLPs and other products and AVANT's expectations regarding market growth; (4) the cost, timing, scope and results of ongoing safety and efficacy trials of CholeraGarde[R] (Peru-15), Ty800, ETEC E. coli vaccine and other preclinical and clinical testing; (5) the ability to negotiate strategic partnerships or other disposition transactions for AVANT's cardiovascular programs, including TP10 and CETi; (6) the ability of AVANT to manage multiple clinical trials for a variety of product candidates; (7) AVANT's expectations regarding its technological capabilities and expanding its focus to broader markets for vaccines; (8) the Company's expectations regarding the cost of funding its development partnership with Select Vaccines Limited for the influenza vaccine, the opportunity to extend to other disease targets, and AVANT's ability to develop products through this collaboration; (9) changes in existing and potential relationships with corporate collaborators; (10) the availability, cost, delivery and quality of clinical and commercial grade materials produced at AVANT's own Manufacturing facility or supplied by contract manufacturers and partners; (11) the timing, cost and uncertainty of obtaining regulatory approvals; (12) the ability to develop and commercialize products before competitors that are superior to the alternatives developed by competitors; (13) the ability to retain certain members of management;(14) AVANT's expectations regarding research and development expenses and general and administrative expenses; (15) AVANT's expectations regarding cash balances, capital requirements, anticipated royalty payments (including those from Paul Royalty Fund), revenues and expenses, including infrastructure expenses; (16) our belief regarding the validity of our patents and potential litigation; and (17) certain other factors that might cause AVANT's actual results to differ materially from those in the forward-looking statements including those set forth under the headings "Business," "Risk Factors" and Management's Discussion and Analysis of Financial Condition and Results of Operations" in each of AVANT's Annual Report on Form 10-K, its Quarterly Reports on Form 8-K, as well as those described in AVANT's other press releases and filings with the Securities and Exchange Commission, from time to time. You should carefully review all of these factors, and you should be aware that there may be other factors that could cause these differences. These forward-looking statements were based on information, plans and estimates at the date of this press release, and AVANT does not promise to update any forward-looking statements to reflect changes in underlying assumptions or factors, new information, future events or other changes.