The utility of the minipig as an animal model in regulatory toxicology

In this article we review the value and utility of the minipig as an animal model in regulatory toxicity testing. Our review is based on detailed consideration of the comparative biology of the minipig, and of the practical features of toxicity testing in the minipig. The minipig presents a favourable profile as a non-rodent toxicology model, in terms of the similarity to man and also in terms of applicability to different study types. Studies of general toxicology can be performed in the minipig by oral, cutaneous, parenteral and inhalation routes. For reproductive toxicology studies the minipig offers numerous advantages as a non-rodent model although the lack of placental transfer of macromolecules may limit the role of the minipig in reproductive testing of biotechnology products. For safety pharmacology studies the minipig is an advantageous model, particularly as regards the cardiovascular system. The immune system of the pig is better characterized than that of the dog, making the pig an interesting alternative model to the nonhuman primate for therapeutic approaches based on manipulation of the immune system. Overall, this review leads us to believe that the minipig might be a better non-rodent toxicology model than the dog. At the present time, however, insufficient comparative data is available to permit a rigorous evaluation of the predictivity of the minipig for human drug-induced toxicities and research is urgently needed to provide experimental data for evaluation of the hypothesis that minipig studies may better reflect human drug-induced toxicities than studies performed in traditional non-rodent toxicology models. It would be of particular value to gain a better vision of the potential utility of the minipig as a model for the safety testing of new biologics, where the minipig could potentially replace the use of non-human primates in the testing of some new products.