Valortim is a fully human antibody developed by Medarex’s UltiMAb human antibody development system that targets the bacillus anthracis protective antigen.
The research, presented at the Infectious Diseases Society of America’s (IDSA) annual meeting held in San Francisco, was conducted in order to better understand the high level of potency exhibited by Valortim in both prophylaxis and treatment preclinical studies.
Valortim works by binding to the protective antigen (PA) component of anthrax toxin and appears to interfere with the normal formation or function of the anthrax toxin complex on macrophage and dendritic cells, which are believed to be critical cells in the natural defense of the immune system against anthrax and are prime targets of the anthrax toxin complex in causing disease.
In addition to binding to PA, study results suggest that Valortim also interacts with a receptor on the surface of macrophage and dendritic cells known as the Fc receptor (FcR).
The three-way interaction between Valortim, anthrax PA, and FcR on macrophage and dendritic cells appears to result in an efficient and potent neutralization of the toxin complex. This mechanism has not been previously described in studies of other known anthrax neutralizing antibodies.
“We are very pleased with the progress of the development of Valortim as both a potential treatment and prophylaxis. We believe that due to its unique mechanism of action with regard to other antibodies, demonstrated efficacy in two animal models, and its potency in animal studies at the lowest dose reported, Valortim is the leading candidate for Project Bioshield procurement,” said David Wright, president and CEO of PharmAthene.