AVANT's Single-Dose Oral Ty800 Vaccine Meets Primary Endpoints in Phase 2 Study

NEEDHAM, Mass.--(BUSINESS WIRE)--Apr 1, 2008 - AVANT Immunotherapeutics, Inc. (Nasdaq: AVAN) announced today that the double-blind, placebo-controlled multi-center Phase 2 clinical trial of its typhoid fever vaccine candidate, Ty800, met all primary endpoints. The Phase 2 study was an out-patient, dose-ranging clinical trial in 183 healthy volunteers that evaluated two dose levels of the Ty800 vaccine and followed each subject for six months post-vaccination. The endpoints of the Phase 2 study were to determine the optimal dose of Ty800 for further development based on the safety, reactogenicity, and immunogenicity of the vaccine.

Data from the trial showed that the single-dose, oral vaccine was well tolerated and immunogenic, demonstrating that the desired immune response was achieved. Incidence of reactogenicity symptoms and adverse events post-vaccination were similar to placebo. Importantly, immunogenic response was dose-dependent. Positive immune response or seroconversion (prospectively defined as a 4-fold increase in anti-LPS titers over pre-dose level) rates were 65.5% (36/55) and 80% (44/55) in the low and high dose groups, respectively, and was significantly (p less than 0.001) higher than placebo.

"The Ty800 data indicate that AVANT's vaccine may have significant potential advantages over currently licensed vaccines, in term of safety, protectivity and ease of administration," said Una S. Ryan, Ph.D., President and Chief Executive Officer of AVANT Immunotherapeutics, Inc. "Available vaccines are given by either single needle injection or three to four oral doses over the course of two weeks. We believe a more efficacious, single-dose oral typhoid fever vaccine could greatly expand the current markets for both travelers in developed countries and mass immunization programs in developing countries. The typhoid fever vaccine market currently has over $200 million in annual sales."

AVANT is advancing its vaccine programs toward creating a "Super Combination Traveler's Vaccine." The "Super Vaccine" is designed to capture the potential of our single-dose oral delivery platforms to provide combined protection against multiple bacterial diseases including cholera, typhoid, ETEC (enterotoxigenic E. coli) and paratyphoid in one convenient and efficient vaccine for world travelers.

About the Ty800 Vaccine

AVANT has designed the Ty800 vaccine to offer rapid, oral, single-dose protection against Salmonella typhi, the cause of typhoid fever. The Ty800 vaccine was developed using genetic techniques to delete specific genes known to be essential to the virulence of S. typhi. The clinical trial was designed to show whether Ty800 is well tolerated in humans and rapidly elicit strong immune responses.

The Study

A total of 183 healthy adult volunteers were randomized at five centers across the US, including 60 subjects (120 total) assigned to each of the Ty800 dose levels, 1x10(8) and 1x10(9) colony-forming units (CFUs), and 63 subjects assigned to placebo control (buffer only). The volunteers were evenly divided among the three treatment groups in terms of age, gender, race, weight and height. The doses used in this study were immunogenic with similar safety and reactogenicity as placebo. Following vaccine administration, anti-LPS titers levels rose and were significantly (p less than 0.001) higher among Ty800 treated subjects compared to placebo controls at all timepoints tested.

About Typhoid Fever

Typhoid fever is a potentially life-threatening infection of the intestinal tract caused by the bacterium Salmonella typhi. It is transmitted by ingestion of food or water contaminated by the feces from an infected person. According to the Centers for Disease Control, an estimated 22 million cases of typhoid fever and 200,000 related deaths occur worldwide each year. In the United States, incidence of the disease is reported mainly in recent travelers to areas of the world where typhoid fever is endemic. Risk is greatest for travelers to South Asia and developing countries in Asia, Africa, the Caribbean and Central and South America. There are two current vaccines for typhoid fever, a four-dose oral vaccine and an intramuscularly injected vaccine, both of which provide protection to only 50-80% of recipients.

About AVANT Immunotherapeutics, Inc.

AVANT Immunotherapeutics, Inc. is a NASDAQ-listed company discovering and developing innovative vaccines and targeted immunotherapeutics for the treatment of cancer, infectious and inflammatory diseases. AVANT focuses on the use of tumor-specific targets and human monoclonal antibodies (mAbs) to precisely deliver therapeutic agents through its novel "targeted immunization" approach. AVANT also possesses innovative bacterial vector delivery technologies with unique manufacturing and preservation processes that offer the potential for a new generation of infectious disease vaccines. AVANT's deep product pipeline consists of products in varying stages of development, with its lead candidate, CDX-110, currently undergoing evaluation in a Phase 2/3 clinical trial in newly diagnosed glioblastoma multiforme, one of the most aggressive forms of brain cancer. AVANT also has five product candidates in its development pipeline including:

-- CDX-1307, a product based on its proprietary APC Targeting Technology(TM), which is in two Phase 1 clinical trials for patients with advanced pancreatic, bladder, breast and colon cancer;

-- a complement inhibitor, TP10, in development for transplantation and other indications; and

-- three candidates based on its oral, rapidly-protecting, single-dose and temperature-stable vaccine technology, including combination vaccines for travelers, the military and global health needs.

AVANT has three commercialized products, including Rotarix(R) for the prevention of rotavirus infection and two human food safety vaccines for reducing salmonella infection in chickens and eggs. Additional information on AVANT Immunotherapeutics, Inc. can be obtained through its 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 successful integration of the business post-merger, multiple technologies and programs; (2) the ability to adopt AVANT's APC Targeting Technology(TM) to develop new, safe and effective vaccines against oncology and infectious disease indications; (3) the ability to adapt AVANT's vectoring systems to develop new, safe and effective orally administered vaccines against disease causing agents; (4) the ability to successfully complete product research and further development, including animal, pre-clinical and clinical studies, and commercialization of CDX-110, CDX-1307, CholeraGarde(R) (Peru-15), Ty800, ETEC E. coli vaccine, and other products and AVANT's expectations regarding market growth; (5) the cost, timing, scope and results of ongoing safety and efficacy trials of CDX-110, CDX-1307, CholeraGarde(R) (Peru-15), Ty800, ETEC E. coli vaccine and other preclinical and clinical testing; (6) the ability to negotiate strategic partnerships or other disposition transactions for AVANT's cardiovascular programs, including TP10 and CETi; (7) the ability of AVANT to manage multiple clinical trials for a variety of product candidates; (8) the volume and profitability of product sales of Megan(R)Vac 1, Megan(R)Egg and other future products; (9) the process of obtaining regulatory approval for the sale of Rotarix(R) in major commercial markets, as well as the timing and success of worldwide commercialization of Rotarix(R) by our partner, GlaxoSmithKline or Glaxo; (10) Glaxo's strategy and business plans to launch and supply Rotarix(R) worldwide, including in the U.S. and other major markets and its payment of royalties to AVANT; (11) AVANT's expectations regarding its technological capabilities and expanding its focus to broader markets for vaccines; (12) changes in existing and potential relationships with corporate collaborators; (13) 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; (14) the timing, cost and uncertainty of obtaining regulatory approvals; (15) AVANT's ability to develop and commercialize products before competitors that are superior to the alternatives developed by such competitors; (16) AVANT's ability to retain certain members of management;(17) AVANT's expectations regarding research and development expenses and general and administrative expenses; (18) AVANT's expectations regarding cash balances, capital requirements, anticipated royalty payments (including those from Paul Royalty Fund), revenues and expenses, including infrastructure expenses; (19) the ability to obtain substantial additional funding; (20) AVANT's belief regarding the validity of our patents and potential litigation; and (21) 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 current 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.

Contact

AVANT Immunotherapeutics, Inc.
Una S. Ryan, Ph.D., 781-433-0771
President and CEO
or
Avery W. Catlin, 781-433-0771
Chief Financial Officer
info@avantimmune.com
or
For Media:
BMC Communications Group
Daniel Budwick, 212-477-9007
dbudwick@bmccommunications.com

Posted: April 2008

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