Objectives: Immunodeficient mice injected with human cancer cell lines have been used for human oncology studies and anti-cancer drug trials for several decades. However, rodents are not ideal species for modelling human cancer because rodents are physiologically dissimilar to humans. Therefore, anti-tumour drugs tested effective in rodents have a failure rate of 90% or higher in phase III clinical trials. Pigs are similar to humans in size, anatomy, physiology and drug metabolism rate, rendering them a desirable pre-clinical animal model for assessing anti-cancer drugs. However, xenogeneic immune rejection is a major barrier to the use of pigs as hosts for human tumours. Interleukin (IL)-2 receptor γ (IL2RG), a common signalling subunit for multiple immune cytokines including IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21, is required for proper lymphoid development.
Materials and methods: IL2RG-/Y pigs were generated by CRISPR/Cas9 technology, and examined for immunodeficiency and ability to support human oncogenesis.
Results: Compared to age-matched wild-type pigs, IL2RG-/Y pigs exhibited a severely impaired immune system as shown by lymphopenia, lymphoid organ atrophy, poor immunoglobulin function, and T- and NK-cell deficiency. Human melanoma Mel888 cells generated tumours in IL2RG-/Y pigs but not in wild-type littermates. The human tumours grew faster in IL2RG-/Y pigs than in nude mice.
Conclusions: Our results indicate that these pigs are promising hosts for modelling human cancer in vivo, which may aid in the discovery and development of anti-cancer drugs.
Keywords: IL2RG knockout minipig; anti-cancer drug trials; in vivo tumour model; tumours; xenogeneic immune rejection.
© 2020 The Authors. Cell Proliferation Published by John Wiley & Sons Ltd.