Baxter's Bird Flu Vaccine Shows Efficacy Against H5N1

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The New England Journal of Medicine publication showing that Baxter's bird flu candidate vaccine induced neutralizing antibodies against widely divergent H5N1 virus.

Baxter International Inc. (NYSE: BAX) announced publication in the June 12, 2008 issue of The New England Journal of Medicine (NEJM) of data demonstrating Baxter's candidate avian influenza (H5N1) vaccine, CELVAPAN, met Phase I/II trial endpoints for safety and immunogenicity (generating a functional immune response). This is the first peer-reviewed publication of study results for CELVAPAN, the first cell culture-derived avian influenza vaccine to undergo clinical evaluation. The primary authors of the manuscript are Hartmut J. Ehrlich, MD, vice president of global research and development for Baxter's BioScience business, and Noel Barrett, vice president of Baxter's vaccines research.

"Cell culture technology could represent the future of influenza vaccine production," said John Oxford, professor of Virology, The Queen Mary School of Medicine, London, United Kingdom. "Baxter has demonstrated the ability to rapidly make large quantities of the vaccine that may protect people against divergent H5N1 viruses."

Based on manufacturing processes, Vero cell technology may offer several advantages versus conventional egg-based vaccine technology. Baxter's Vero cell manufacturing process is more rapid due to its ability to use a "native" virus that does not need to be modified to allow growth in chicken eggs, therefore accelerating vaccine production.

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"CELVAPAN combines innovative science and breakthrough production technology with the aim of protecting people against an H5N1 pandemic flu infection," said Hartmut J. Ehrlich, MD. "This is an immunogenic vaccine without the need for an adjuvant to boost the immune response."

CELVAPAN is manufactured in a cell culture-based system in Bohumil, Czech Republic, at one of the largest cell culture vaccine production facilities in the world. Vero cell technology uses a well-established cell line originally derived from African green monkey kidneys in 1962. A continuous cell line has been derived from these cells so that an unlimited supply of cells is available without the requirement of generating additional cells from animals.

Baxter's candidate avian flu vaccine is derived from the H5N1 strain A/Vietnam/1203/2004. Its antigen composition and structure are identical to the actual virus circulating in nature without the need to enhance an immune response by including adjuvants, additives that may cause side effects. In this Phase I/II study, CELVAPAN induced an immune response that is similar to the body's defense against a natural virus infection. Earlier this year CELVAPAN was accepted for licensure review by the Committee for Medicinal Products for Human Use within the European Medicines Agency, making it the first cell culture-based pandemic influenza vaccine to be reviewed by the regulatory authority. The U.S. National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, is also conducting a trial with Baxter's CELVAPAN in the United States.

The randomized Phase I/II study enrolled 284 subjects in Austria and Singapore (ages 18-45) and met its immunogenicity and safety endpoints. The study mainly investigated the ability of the vaccine to induce substantial levels of cross-immunity against divergent H5N1 strains.

The trial tested four different antigen concentrations ranging from 3.75

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