Baxter International Inc. (NYSE: BAX) recently announced promising initial study data for its candidate, Vero cell-based seasonal influenza vaccine, now undergoing a Phase I/II clinical trial in Europe. The preliminary data indicate that the vaccine induced strong antibody responses and good tolerability in all study populations.

The findings were presented by Hartmut J. Ehrlich, M.D., vice president of Global Research and Development for Baxter’s BioScience business at a June gathering of laboratory and clinical scientists and public health professionals at the Options for the Control of Influenza VI Conference in Toronto, Canada. The active, controlled, multi-center Phase I/II trial of the seasonal influenza vaccine was designed to evaluate safety and immunogenicity of the candidate vaccine in approximately 940 subjects divided between the ages of 18-49 and 50 years of age and older.

The Phase I/II study data indicate that Baxter’s seasonal candidate vaccine, which was developed using a split virus process, was effective in inducing protective levels of antibodies for all three seasonal virus strains in both age levels. Split viruses are most frequently used for seasonal influenza vaccines. Baxter’s investigational pandemic H5N1 influenza vaccine, currently in Phase III trials in Europe, was developed using a whole-virus process.

In the 18-49 subject population, 99.6 percent achieved protective antibody levels for virus strains H1N1 and H3N2, and 92.9 percent for strain B. In the 50 years of age and older population, 96.6 percent achieved protective levels for virus strain H1N1, 100 percent for H3N2 and 73.3 percent for strain B.

Work on this vaccine is being completed as part of a U.S. Department of Health and Human Services (DHHS) Office of Public Health and Emergency Preparedness contract awarded to DynPort Vaccine Company LLC (DVC), a Computer Sciences Corporation (NYSE: CSC) company, and Baxter in May 2006 to develop seasonal and pandemic influenza vaccines. Under this contract, DVC is managing the project and clinical trials. Baxter is manufacturing the vaccines and will serve as the U.S. Food and Drug Administration (FDA) license-holder.

“I am very encouraged by the preliminary results of this Phase I/II clinical trial, which suggest that this cell culture-derived vaccine may provide protection against seasonal influenza with minimal side effects,” said Frank von Sonnenburg, M.D., head of the Section of International Medicine and Public Health in the Department of Infectious Diseases and Tropical Medicine at the University of Munich.

Baxter’s seasonal influenza candidate vaccine is manufactured using the company’s proprietary Vero cell technology. The use of Vero cell culture, rather than conventional egg-based technology, offers several advantages. Baxter’s Vero cell culture process can be initiated more rapidly due to its use of a “native” virus that does not need to be modified to allow growth in eggs, thus accelerating vaccine availability. Vaccines produced using the process can be released within approximately 12 weeks, significantly earlier than with traditional egg-based systems. In addition, all influenza strains with pandemic potential tested for growth in Vero cells have produced consistent high yields, providing the flexibility to quickly respond to emerging variant pandemic virus strains.

“Combined with the recent encouraging results from our pandemic H5N1 clinical trial, these data provide further evidence suggesting the Vero cell platform can reliably deliver safe and effective influenza vaccines in pandemic or interpandemic situations,” said Dr. Noel Barrett, vice president of Global Research and Development for Baxter’s Vaccines Business. “This early indication of an acceptable safety profile and immunity against key seasonal influenza viral strains is critically important as we plan the Phase III clinical trial program to provide a solid measure of the vaccine’s potential to protect a large number of people during the influenza season.”

Phase I/II Data

Preliminary data from the Phase I/II clinical trial presented at the Toronto meeting showed the candidate vaccine’s tolerability profile to be similar to currently marketed, egg-based seasonal flu vaccines. The vaccine also generated substantial levels of cross immunity against three seasonal strains. The most common side effects observed for the trial vaccine were injection site reactions, headaches and malaise.

In addition, the analysis demonstrated that the vaccine met European Committee for Medicinal Products for Human Use (CHMP) criterion for influenza vaccine licensure with all three strains, in both age groups tested. The criterion requires that adults achieve specific levels of immunity or “seroprotection” following vaccination.

ACKNOWLEDGEMENTS:

1. This project has been funded in whole or in part with Federal (United States Government) funds from the Office of Public Health Emergency Preparedness, Office of Research and Development Coordination, under contract number HHS0100200600013C.

2. Pursuant to Section 507 of P.L. 104-208 and Section 508 of P.L. 105-78; 100% of the total of this project’s costs are financed with Federal (United States Government) money.

3. The content of this publication does not necessarily reflect the views or policies of the United States Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.