In a presentation titled "Ascending Dose Safety and Immunogenicity Study of a Recombinant Protective Antigen (PA) Anthrax Vaccine (rPA102) [Slide Session No. 57]1," researchers demonstrated that the immune responses to VaxGen's rPA102 at the higher doses (50 g and 75 g) were comparable to that of AVA, despite a 10-fold greater amount of aluminum adjuvant, an immune stimulant, in AVA.
There was a clear relationship between the amount of rPA102 administered and the subsequent immune response, with antibody titers continuing to increase after the second and third administration of the vaccine candidate at each dose level. rPA102 was well-tolerated, with no evidence of dose-limiting toxicity or reactogenicity at any dose. Harry L. Keyserling, M.D., Professor of Pediatrics, Emory University School of Medicine, along with colleagues at St. Louis University Health Sciences Center, Johns Hopkins University Bloomberg School of Public Health, Baylor College of Medicine and VaxGen, conducted the research presented at ICEID.
"Despite formulations that had a tenth of the adjuvant content, antibody responses at the higher dose levels of rPA102 were within the same range as those associated with AVA," said Dr. Keyserling, one of four principal investigators for the study. "We are encouraged to find that increasing concentrations of rPA102 elicited a greater immune response with no significant increase in reactions.
Contact: Kesinee Angkustsiri Yip