Animal models as indicators of immunogenicity of therapeutic proteins in humans.

Animal models have not been able to predict the immunogenicity of therapeutic proteins in humans reliably. The main issue is that administration of a human protein in an animal species is likely to be immunogenic. In non-human primate studies, we have seen a variety of responses; from little to no antibody response, to a strong neutralizing response, or even a cross-reactive antibody response. These have generally not correlated well with the immune response seen in humans. The route of administration, duration and schedule of dosing, the cumulative dosage of the protein, the pharmacological (i.e., immune altering) properties of the protein, as well as the purity of the clinical material can influence the immunogenicity. The animal studies should mimic these factors to the best extent possible for the animal model to be at all relevant to humans. Models do exist which provide valuable information to compare the immunogenicity of various compounds or routes of administration. Presumably, this 'relative' immunogenicity would be similar in humans. Additional characterization of transgenic mice, or use of homologous proteins, may help to establish better models to predict immunogenicity.