( Single-Dose Oral Ty800 Vaccine Immunog...)Avant’s Typhoid Fever Vaccine Demonstrates Excellent Clinical,Potential,Health

Single-Dose Oral Ty800 Vaccine Immunogenic & Well-Tolerated in NIH-Sponsored Phase 1/2 Study

NEEDHAM, MA (May 18, 2007) - AVANT Immunotherapeutics, Inc. (Nasdaq: AVAN) announced today positive preliminary results from an investigational double-blind, placebo-controlled Phase 1/2 dose-escalating clinical trial of its typhoid fever vaccine candidate, Ty800, in healthy volunteers. The researchers found the single-dose, oral vaccine to be well tolerated and immunogenic, with over 90% of vaccinated subjects generating immune responses. Based on these excellent results, AVANT plans to further develop Ty800 to compete in the expanding typhoid fever vaccine market, which currently has over $200 million in annual sales. AVANT plans to initiate its own sponsored Phase 2 dose-ranging trial of Ty800 in mid-2007.

“Typhoid fever remains endemic in many developing areas of the world, as well as being an important potential health threat for travelers and military personnel in areas affected by the disease,” said Dr. Mitchell B. Cohen, Principal Investigator in the study and Director of Gastroenterology, Hepatology and Nutrition at Cincinnati Children’s Hospital Medical Center. “The development of an effective and practical vaccine for all ages will provide an important tool for controlling this disease. A safe typhoid fever vaccine that can be easily administered could significantly reduce the morbidity and mortality associated with typhoid fever.”

“We are delighted with these results for our single-dose, oral Ty800 vaccine candidate,” said Una S. Ryan, Ph.D., President and Chief Executive Officer of AVANT Immunotherapeutics, Inc. “These results indicate that AVANT’s vaccine may have significant potential advantages over the currently licensed vaccines, which offer limited protection rates of 50-80% and require either a single needle injection or three to four oral doses over the course o
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