The Göttingen Minipig was developed at the University in Göttingen, Germany to meet the demand for a non-rodent model with many similarities to humans as genetic management is required to minimise inbreeding and drift and to maintain the genetic integrity of the population. The genetics for the entire breeding population is still managed in Göttingen and all breeding data dates back to the 1960s when the Göttingen Minipig was developed. The entire breeding population is found in three physical locations (Dalmose, Denmark, Göttingen, Germany, and North Rose, New York, US). Despite separation into sub-populations, the Göttingen Minipig population is genetically coherent.
Scientifically, the pig is attractive because of similar physiology to humans
The digestive, cardiovascular, and urogenital system resembles the human systems, while the anatomy of the skin is very similar to the human skin. Also, metabolic activity and enzymatic processes have close parallels to the human situation. There are some areas of pharmacological research where pigs and minipigs are established research models mainly because of anatomical similarities to humans (e.g. body size, skin, cardiovascular system, and urinary system), because of functional similarities (gastrointestinal system and immune system), or because of availability of disease models (e.g. arteriosclerosis, metabolic syndrome, gastric ulcer, and wound healing). But with increasing ethical concerns relating to the use of primates and increasing problems with regard to the supply of non-human primates the use of minipigs in non-clinical safety testing is rising in general, even moving beyond ‘standard’ small molecule drugs like biopharmaceuticals and single-stranded oligonucleotides (SSOs).
Whether or not studies using minipigs to support the safety of products (pharmaceuticals, biocides, cosmetics, other chemicals as well as medical devices) will be acceptable to authorities is not spelled out in regulatory guidance documents. To investigate the safety of new pharmaceuticals for human use, most often the dog (through long tradition) is still selected as non-rodent species. And when dogs are not appropriate, in many cases non-human primates are still chosen as an alternative. In the period 2006-2010, the RETHINK European FP6 Project investigated and published 8 papers on the acceptability and usefulness of minipigs in the regulatory arenas of human and veterinary pharmaceuticals, food additives, cosmetics, biocides and agrochemicals, chemicals, and medical devices. They concluded from information in the public domain as well as literature from the EMA and FDA, that minipigs already were identified as suitable to take the role of non-rodent species in toxicity testing of pharmaceutical products. And after reviewing the costs of testing in minipigs, they concluded that economical reasons should not be used to argue against the use of minipigs instead of dogs or monkeys as these are not significantly higher than the costs for a study in dogs. Minipigs were therefore considered an acceptable choice of species provided adequate justification for this choice is made.
Use of the minipig in embryofoetal development studies
In studies for effects on embryofoetal development, two mammalian species have traditionally been required, one rodent and one non-rodent species. Because of practicality and a large amount of historical background data, the predominant rodent and non-rodent species are the rat and rabbit, respectively. In some cases, the use of these species is found unsuitable, because of significant differences in the metabolism and kinetics of a test item compared to humans, or test item or dose route related harmful effects on the health of the mother. In such cases, the microbiologically defined, genetically stable Göttingen Minipig could be a possible non-rodent alternative.
The first embryofoetal development studies in Göttingen Minipigs were performed more than 20 years ago and since then a significant amount of experience and background data have been gathered and published. Minipigs are susceptible to known teratogens and characteristics such as availability, the onset of sexual maturity and large litter size make the microbiologically defined, genetically stable Göttingen Minipigs an attractive species for embryofoetal development studies.
Increased interest in minipigs
There is increased interest and need in developing a minipig model for immunotoxicology testing during drug development. In 2018 the CONFIRM initiative was born, intended to trigger immunological safety research in Göttingen Minipigs, to assist and synergize fundamental, translational and regulatory investigative efforts relevant to the immunological safety evaluation of pharmaceuticals and biologics, and to spread current knowledge and new findings to the scientific and regulatory toxicology community. The minipig provided sufficient exposure as a large animal species and fewer immunotoxicological effects were observed in mice. The overall conclusions were that mini pigs are developing to be a translationally relevant immunosafety model but that additional work is still needed.
By François van Och – Toxicologist