Comparative analysis of binding affinities to epidermal growth factor receptor of monoclonal antibodies nimotuzumab and cetuximab using different experimental animal models.

Although pharmaco/toxicological studies have always been conducted in pharmacologically relevant species in which the test material is pharmacologically active, the very specificity of many biopharmaceuticals could present challenges in the identification of a relevant species for pharmaco/toxicological studies. Alternative approaches may improve the predictive value of preclinical assessments of species-specific biopharmaceuticals. This could lead to improved decision-making, reduce the number of experimental animals by eliminating non-relevant studies, and decrease the time and cost involved in the drug development process. As an alternative to utilizing traditional animal models, this study investigated the activity of human EGF and the anti-EGF receptor monoclonal antibodies nimotuzumab and cetuximab using the placenta microsomal fraction of different experimental animals. Ligand-receptor binding curves were obtained from the different experimental animal models, and binding constants were calculated based on the Scatchard plots. The constants for human and monkey EGF receptor expressed on the placental extract showed a K(a)<10(-8)M, while rabbits, mice and rats showed a K(a)>10(-8)M. The K(a) values obtained from animal placentas show that Macaca fascicularis and Cercopitecus aethiops monkeys are relevant species for studying the pharmaco/toxicological properties of nimotuzumab and cetuximab.