Failure of trial of H5N1 influenza patch revealed

The reason for the failure of a Phase II clinical trial of Intercell AG's Vaccine Enhancement Patch for H5N1 influenza could be a faulty hemagglutinin inhibition assay, a newly released report reveals.

The patch is administered alongside a single vaccine shot and is meant to support dose-sparing efforts should an influenza pandemic arise, BioWorld.com reports.

The Phase II clinical trial was conducted under a $128 million contract with the U.S. Department of Health and Human Services. Two different doses of H5N1 influenza vaccine were tested in 500 subjects. No difference was found in seroprotection rates between those who had received both the vaccine as well as the VEP and those who only received the vaccine.

The results contradict an earlier study by Iomai Corp., the original developers of the patch system. In that study, a protective immune response was achieved in 73 percent of those who received both the vaccine and the patch, notably more than those who received the vaccine alone. In Iomai's study, a different hemagglutinin inhibition assay was used that is no longer available.

"At this stage, we think we have a good chance that the DHHS will continue to fund the program." The DHHS has already provided approximately $30 million in funding but may withdraw from the program at any point, though Reinhard Kandera, chief financial officer at Intercell, expressed hope to BioWorld.com that DHHS will continue to fund the program.

In future trials, Intercell will have access to a proprietary GSK hemagglutinin inhibition assay, one optimized for H5N1 influenza.