Vaxin Inc., a privately-held biotechnology company, has demonstrated, in a Phase I human clinical study, that the company's recombinant influenza vaccine provides a potential alternative to traditional flu vaccines.
Published in the January 11, 2005 issue of the journal Vaccine, the paper is entitled "Safety and immunogenicity of adenovirus-vectored nasal and epicutaneous influenza vaccines in humans." The authors conclude that Vaxin's novel flu vaccine, which is produced in cell culture, was immunogenic and well tolerated by human volunteers.
"To our knowledge, this represents the first report of a recombinant influenza vaccine using a non-replicating adenovirus vector delivered either nasally or epicutaneously (to the surface of the skin)," said De-chu C. Tang, Ph.D., corresponding author and Vice President and Chief Technical Officer of Vaxin.
The study was designed to determine whether humans can be immunized by a recombinant influenza vaccine, using the hemagglutinin (HA) gene from the PR8 (H1N1) influenza strain, contained within a non-replicating adenovirus vector. There were 24 study participants (healthy adults, age 20-31), in 4 groups. Groups 1, 2 and 3 received increasing doses delivered to the skin, respectively. Group 4 received the dose intra-nasally.
At a dose approximately 1000-fold lower (108 vs. 1011 virus particles) the nasal vaccine elicited a stronger immune response as compared to the vaccine delivered to the skin. 67% of the nasal vaccine recipients developed a 4-fold antibody rise after one dose, which increased to 83% after a second dose. Immune response is a function of serum antibody level, and a 4-fold or better rise in serum antibody level is considered "protective."
There was no correlation between pre-existing levels of antibody to adenovirus, and the ability to achieve a four-fold rise in antibody to the influenza antigen. This finding indicates that the recombinant influenza vaccine may not be affected by pre-existing antibodies to the adenovirus vector when delivery is intranasal.
"We are very pleased to report these encouraging findings from our proof- of-principle human clinical trial," commented Frank Cano, Ph.D., Chairman and Chief Executive Officer of Vaxin. "These results are impressive given the low dose administered to the nose, especially since the PR8 strain is known to be inherently poorly immunogenic. The results support further study of intranasal administration, using increased dose levels and other influenza strains."