Baxter Announces Early Bird Flu Vaccine Promising

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Bird Flu Vaccine Trial

Baxter International Inc. today announced results from a preliminary evaluation of its Phase I/II clinical trial of whole-virus H5N1 influenza candidate vaccine. The results represent the first clinical evaluation of a vero cell-based candidate H5N1 pandemic vaccine.

The candidate H5N1 pandemic vaccine was produced using the company's proprietary vero cell-based technology platform and inactivated wild-type H5N1 strain A/Vietnam/1203/2004. The clinical trial was conducted in 270 healthy adults in Austria and Singapore using four different antigen concentrations ranging from 3.75mcg to 30mcg in formulations. The 7.5mcg and 15mcg antigen concentrations were tested with and without adjuvant, a substance added to vaccines to improve immune response.

"We are extremely pleased with the clinical results from this study," said Noel Barrett, Ph.D., vice president of Global R&D for Baxter's vaccines business. "We have achieved an important step toward our goal of producing a safe and efficacious pandemic vaccine using the company's proprietary vero cell-based technology."

Hartmut Ehrlich, M.D., vice president of Global R&D for Baxter BioScience added: "This is the first clinical demonstration that a candidate H5N1 vaccine can induce antibodies that neutralize widely divergent strains of H5N1. These preliminary data, which must be confirmed in a larger study, suggest that the vaccine may provide wider protection for a larger number of people before and during a pandemic."

Preliminary results from this trial suggest that the vaccine is well tolerated in humans: the occurrence and severity of side effects at all dose levels are similar to what has been reported for licensed interpandemic (or seasonal) influenza vaccines. Most common side effects are injection site reactions, headaches and fatigue.

In addition, the preliminary results suggest that the vaccine is highly immunogenic and elicits functional antibodies to H5N1 even at the lowest dose level of 3.75mcg. Importantly, preliminary analysis of serum samples obtained from the study subjects suggests both the neutralization of the pandemic virus contained in the vaccine and cross-neutralization against widely diverse strains of H5N1, including both Hongkong/156/97 and Indonesia/05/05.

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"These preliminary results are encouraging," said Professor Frank von Sonnenburg, M.D., who heads the Section of International Medicine and Public Health within the Department of Infectious Diseases and Tropical Medicine at the University of Munich, and chairs the Data Safety and Monitoring Board for the clinical study. "If confirmed in Phase III results, the suggested safety and immunogenicity of this cell-culture derived whole virus vaccine indicate its potential to make a major contribution to public health in preparing for and combating an influenza pandemic situation."

Baxter plans to present the initial results of the Phase I/II clinical trial October 11 at the World Vaccine Congress in Lyon, France, and October 20 during the Second International Conference on "Influenza Vaccines for the World" in Vienna, Austria, with final results available by the end of 2006.

The company also plans to begin a Phase III clinical trial of the candidate pandemic vaccine early next year and present final results by the end of 2007.

In addition to this Baxter funded Phase I/II clinical trial, the company is separately involved with the U.S. Government in other vero cell-based influenza vaccine development programs. Baxter is working with the U.S. National Institute of Allergy and Infectious Diseases, in partnership with Fisher BioServices Inc., and with the U.S. Department of Health and Human Services, in partnership with DVC LLC, a Computer Sciences Corporation Company, to further develop vero cell-based pandemic and seasonal influenza candidate vaccines. Both collaborations are the result of U.S. Government contract awards. Baxter and its partners will providethe vero cell-based candidate vaccines to the agencies for further clinical testing in the United States, which is expected to begin by the end of this year.

Baxter also is in discussions with a number of other governments regarding its proprietary vero cell-based candidate pandemic vaccine. Earlier this year, Baxter received a contract award to supply two million doses of cell-culture based candidate H5N1 vaccine to the U.K. Government.

Cell-based systems for production of vaccines offer a number of potential benefits over more traditional egg-based systems. Baxter's vero cell technology is capable of producing high yields of influenza virus without the addition of any animal-derived serum. Through the company's research and development work, Baxter has been successful in growing "wild-type" virus at pilot and commercial scales using its unique vero cell technology. This means the company is capable of manufacturing pandemic vaccine without the need to wait for high-growth or attenuated virus reassortants normally used when vaccine is produced in eggs.

Baxter is developing both seasonal (or inter-pandemic) and pandemic influenza vaccines based on the company's vero cell technology. Baxter has one of the largest existing cell-culture facilities in the world, capable of manufacturing large quantities of vaccine. Because the facility is engineered for BioSafety Level III production, the facility can utilize "wild type" pandemic strains to help accelerate production and reduce the total time required to produce vaccine by several weeks. Baxter's technology platform also allows it to implement rapid changes in strains that may be needed for new vaccine formulations.

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