The Lancet publishes Baxter's PREFLUCEL phase III trial results against seasonal influenza

Baxter International Inc. announced today results of a study published in this week's issue of The Lancet that demonstrate effectiveness and tolerability of Baxter's PREFLUCEL in protecting against seasonal influenza. The study data show nearly 80 percent protective efficacy against the influenza strains contained in the vaccine and a low adverse event profile. PREFLUCEL is manufactured using Vero cell technology, offering an innovative method of vaccine production compared to conventional embryonated chicken egg production, which has been used for decades.

Investigators studied the safety, immunogenicity and protective efficacy of PREFLUCEL through a randomized, double-blind, placebo-controlled phase III trial conducted in more than 7,200 healthy volunteers in the United States during the 2008/2009 influenza season.

"Seasonal influenza claims thousands of lives every year, but can be very effectively prevented through wide-spread vaccination," said Professor John Oxford, D.Sc., Barts and The London School of Medicine and Dentistry, Queen Mary, University of London. "This study provides important new information that Baxter's Vero cell-derived seasonal vaccine is well-tolerated, immunogenic and efficacious and should be considered when planning public health preventive efforts around flu season."

Study results indicated that participants responded positively to the vaccine, with 78.5 percent protective efficacy against culture-confirmed influenza infection (CCII) and robust immune responses (measured as seroprotection rates) against the three viral strains contained in the vaccine: A/H1N1- (88.0%), A/H3N2- (93.3%) and B-specific (97.1%). In addition to protection, study investigators found significantly reduced duration and severity of influenza symptoms in infected subjects in the vaccinated group, as compared with the placebo group in a subsequent analysis. The vaccine was well tolerated, with no treatment-related serious adverse events reported during the trial.

"PREFLUCEL has demonstrated robust immunogenicity and protective efficacy against common circulating flu strains, and may provide an important alternative to egg-based vaccines in planning seasonal influenza prevention efforts with a shorter production timeline," said Hartmut Ehrlich, M.D., vice president of global research and development for Baxter's BioScience business, and senior author of the publication. "The positive developments in vaccine cell-culture technologies may help contribute to improved strain selection and more robust vaccine supplies for the growing preventive health efforts around the world."

The study was primarily designed to determine the efficacy of the vaccine in preventing CCII with viruses that were matched to one of the strains contained in the vaccine. Trial protocol also included assessing the correlation between antibody levels and CCII protection, as well as a comparison of the safety of the vaccine versus placebo.

Vero cell technology uses the natural virus, identical in protein composition to the virus circulating in nature, instead of genetically modified virus strains that are widely used for egg-based vaccine production. The resulting vaccine is of high purity because it is free of preservatives, antibiotics and egg proteins, and is suitable for adult and elderly populations, as well as people with egg or antibiotic allergies.

PREFLUCEL is available in Austria and Czech Republic for the 2010 to 2011 influenza season. Baxter expects to receive approval of PREFLUCEL in additional countries in Europe in 2011 through a repeat Mutual Recognition Procedure (rMRP).

Source: Baxter International Inc