Studies on Medium-Term Carcinogenicity Tests Using Genetically Engineered Mice

A long-term carcinogenicity study is required to assess the safety of new drug candidates. This classical toxicological method has been using rats and mice as animal systems. The International Conference on Harmonization of Technical Requirements of Pharmaceuticals for Human Use (ICH) have recommended a long-term rodent carcinogenicity test system using rat and a supplementary mouse test system such as an initiation-promotion model, a transgenic model or a neonatal model. This study was carried out to develop a new liver carcinogenicity model using HBx tg mice and disease model mice. The incidence of liver tumor was increased in treated group at 16, 20 or 26 weeks after carcinogen treatment. It was statistically significant compared with the control animals. We could suggest the possibilities of HBx mice and other disease model as a new carcinogenesis screening model system, and if we have more data about reference chemicals for these animals, it will be recommended as alternative test for carcinogenicity risk assessment and used for a rapid evaluation of hepatocarcinogenicity of several chemical.